java如何實現科學計算器

這篇文章主要介紹了java如何實現科學計算器的相關知識，內容詳細易懂，操作簡單快捷，具有一定借鑒價值，相信大家閱讀完這篇java如何實現科學計算器文章都會有所收獲，下面我們一起來看看吧。

實現思路

通過點擊按鈕可以得到一個算術表達式，并且它是一個字符串類型，然后需要做的就是把這個字符串轉化為計算機可計算的形式。這里就需要用到中綴表達式轉化為后綴表達式。轉化完之后通過棧來一步步的進行輸出和計算，最后輸出結果。

實現過程和代碼

1.界面設計

設計效果如圖所示：

由圖片可知，總共設計了兩個文本框和33個按鈕（這里的布局是我直接用setBounds()方法設計的。因為如果用布局管理器的話要達到自己想要的效果不太方便）。

在設計時要注意的是：

1.不能把按鈕和文本框直接加入JFrame中，因為如果JFrame.setLayout(null)的話，面板上就會出問題，什么都看不到或者其他情況。因此建議創建一個JPanel，把JPanel的setLayout()設置為空。把按鈕和文本框加入到JPanel中，再把JPanel加入到JFrame中。就不會出問題了。JFrame的布局管理器默認為流式布局，位置是中心區域。

2.設計完長度后，寬度一般要再加15個像素點，高度要再加35個像素點.要不然會有一部分按鈕看不到。如我本意要設計的面板寬為600，高為400，則實際上是

jFrame.setSize(614, 437);

下面就是我設計的界面的代碼：

	private JFrame jFrame = new JFrame("計算器");
	//設置字體，是否加粗，大小
    private FontUIResource f = new FontUIResource("隸書", 1, 20);
    private FontUIResource f1 = new FontUIResource("楷書", 0, 35);
    private JPanel jPanel = new JPanel();
    private int buttonx = 100;
    private int buttony = 50;
    private int yy = 50;
    //兩個文本框
    private JTextField jTextField1 = new JTextField("0", 30);
    private JTextField jTextField2 = new JTextField("輸入要求在main()中", 30);
    private String str = "";
    private String temp = "";
    private int indexYN = 0;
    private String[] strings = {
            "(", ")", "1/x", "x^2", "x^3", "x^y",
            "x!", "√", "e", "ln", "log", "%",
            "sin", "cos", "tan", "π", "+", "=",
            "7", "8", "9", "0", "-",
            "4", "5", "6", ".", "*",
            "1", "2", "3", "c", "÷"
    };
    //33個按鈕
    private JButton[] buttons = new JButton[33];

    public void loAsi(){
        int tep = 0;
        for (int i = 0; i < 3; i++) {
            for (int j = 0; j < 6; j++) {
                buttons[tep] = new JButton(strings[tep]);
                buttons[tep].setFont(f);
                buttons[tep++].setFocusable(false);
            }
        }
        for (int i = 0; i < 3; i++) {
            for (int j = 0; j < 5; j++) {
                buttons[tep] = new JButton(strings[tep]);
                buttons[tep].setFont(f);
                buttons[tep++].setFocusable(false);
            }
        }
        int lo = 0;
        for (int i = 0; i < 2; i++) {
            for (int j = 0; j < 6; j++) {
                buttons[lo++].setBounds(buttonx * j, yy * (2 + i), buttonx, buttony);
            }
        }
        for (int i = 0; i < 5; i++) {
            buttons[lo++].setBounds(buttonx * i, yy * 4, buttonx, buttony);
        }
        buttons[lo++].setBounds(buttonx * 5, yy * 4, buttonx, buttony * 4);
        for (int i = 0; i < 3; i++) {
            for (int j = 0; j < 5; j++) {
                buttons[lo++].setBounds(buttonx * j, yy * (5 + i), buttonx, buttony);
            }
        }
        jTextField1.setBounds(0, yy, 600, yy);//設置位置
        jTextField1.setFont(f1);設置字體
        jTextField1.setHorizontalAlignment(JLabel.RIGHT);//文本靠右
        jTextField1.setEditable(false);//不可修改
        jTextField1.setBackground(Color.WHITE);//顏色為白色
        jTextField2.setBounds(0, 0, 600, yy);
        jTextField2.setFont(f1);
        jTextField2.setHorizontalAlignment(JLabel.RIGHT);
        jTextField2.setEditable(false);
        jTextField2.setBackground(Color.WHITE);
    }
    public void initButton(){//把按鈕添加到jPanel中
        this.loAsi();
        jPanel.add(jTextField1);
        jPanel.add(jTextField2);
        for (int i = 0; i < buttons.length; i++) {
            jPanel.add(buttons[i]);
        }
        jPanel.setLayout(null);//布局管理器為空，自定義設計
    }
     public void init(){
        this.initButton();
        this.buttonLister();
        jFrame.add(jPanel);//把jPanel添加到jFrame中
        jFrame.setSize(614, 437);//jFrame的長寬
        jFrame.setResizable(false);//大小不可修改
        jFrame.setLocationRelativeTo(null);//位置為顯示器的正中間
        //窗口監聽器，點右上角的關閉就關閉窗口
        //可以不寫，應為JFrame默認的就可以關閉，不需要寫事件監聽器。如果是Frame的話需要寫。
        jFrame.addWindowListener(new WindowAdapter() {
            @Override
            public void windowClosing(WindowEvent e) {
                System.exit(0);
            }
        });
        jFrame.setVisible(true);//設置面板可見
    }

2.棧，中綴轉后綴

我總共設計了12種運算符：（+, -, * , /, ^, !, g, l, o, s, c, t）分別是加，減，乘，除，次方，階乘，開根號，，對數ln, 對數log2, sin, cos, tan
e是Math.E, p是Math.PI, %是直接乘以0.001

把中綴表達式轉換為后綴表達式。例如：

中綴表達式：1+2*3+(l2+3)/2

后綴表達式為：123*+23+2/+

后綴表達式的運算步驟是：

1.16+23+2/+
2.723+2/+
3.752/+
4.7 2.5+
5.9.5

代碼如下：

private List<String> zhongZhui(String str) {//把輸入的字符串轉換成中綴表達式。存入list中
        int index = 0;
        List<String> list = new ArrayList<>();
        do{
            char ch = str.charAt(index);
            if("+-*/^!logsct()".indexOf(str.charAt(index)) >= 0){
                //是操作符，直接添加至list中
                index ++;
                list.add(ch+"");
            }else if (str.charAt(index) == 'e' || str.charAt(index) == 'p'){
                index ++;
                list.add(ch+"");
            } else if("0123456789".indexOf(str.charAt(index)) >= 0){
                //是數字,判斷多位數的情況
                String str1 = "";
                while (index < str.length() && "0123456789.".indexOf(str.charAt(index)) >= 0){
                    str1 += str.charAt(index);
                    index ++;
                }
                list.add(str1);

            }
        }while (index < str.length());
        return list;
    }

    public List<String> houZhui(List<String> list){//中綴表達式轉換稱后綴表達式
        Stack<String> fuZhan = new Stack<>();
        List<String> list2 = new ArrayList<>();
        if (!list.isEmpty()) {
            for (int i = 0; i < list.size(); i++) {
                if (isNumber(list.get(i))){
                    list2.add(list.get(i));
                } else if (list.get(i).charAt(0) == '('){
                    fuZhan.push(list.get(i));
                } else if (isOperator(list.get(i)) && list.get(i).charAt(0) != '('){
                    if (fuZhan.isEmpty()){
                        fuZhan.push(list.get(i));
                    } else {//符棧不為空
                        if (list.get(i).charAt(0) != ')'){
                            if (adv(fuZhan.peek()) <= adv(list.get(i))){
                                //入棧
                                fuZhan.push(list.get(i));
                            } else {//出棧
                                while (!fuZhan.isEmpty() && !"(".equals(fuZhan.peek())){
                                    if(adv(list.get(i)) <= adv(fuZhan.peek())){
                                        list2.add(fuZhan.pop());
                                    }
                                }
                                if (fuZhan.isEmpty() || fuZhan.peek().charAt(0) == '('){
                                    fuZhan.push(list.get(i));
                                }
                            }
                        } else if (list.get(i).charAt(0) == ')'){
                            while (fuZhan.peek().charAt(0) != '('){
                                list2.add(fuZhan.pop());
                            }
                            fuZhan.pop();
                        }
                    }
                }
            }
            while (!fuZhan.isEmpty()){
                list2.add(fuZhan.pop());
            }
        } else {
            jTextField1.setText("");
        }
        return list2;
    }
    public static boolean isOperator(String op){//判斷是否為操作符
        if ("0123456789.ep".indexOf(op.charAt(0)) == -1) {
            return true;
        } else {
            return false;
        }
    }
    public static boolean isNumber(String num){//判斷是否為操作數
        if ("0123456789ep".indexOf(num.charAt(0)) >= 0) {
            return true;
        } else {
            return false;
        }
    }
    public static int adv(String f){//判斷操作符的優先級
        int result = 0;
        switch(f) {
            case "+":
                result = 1;
                break;
            case "-":
                result = 1;
                break;
            case "*":
                result = 2;
                break;
            case "/":
                result = 2;
                break;
            case "^":
                result = 3;
                break;
            case "!":
                result = 4;
                break;
            case "g":
                result = 4;
                break;
            case "l":
                result = 4;
                break;
            case "o":
                result = 4;
                break;
            case "s":
                result = 4;
                break;
            case "c":
                result = 4;
                break;
            case "t":
                result = 4;
                break;
        }
        return result;
    }

3.判斷錯誤

下面是一些我能想到的一些輸入錯誤和運算錯誤：

//當只有一位字符時，只能是“0123456789ep”中的一個
//1.第一個字符只能為"losctg(0123456789ep"中的一個
//2.“±/”后面只能是"0123456789losctg(ep"中的一個
//3.".“后面只能是“0123456789”中的一個
//4.”!"后面只能是“±/^)”中的一個
//5."losctg"后面只能是“0123456789(ep”中的一個
//6."0"的判斷操作
//1.當0的上一個字符不為"0123456789."時，后一位只能是“±/.!^)”中的一個
//2.如果0的上一位為“.”,則后一位只能是“0123456789±/.^)”中的一個
//3.如果0到上一個運算符之間沒有“.”的話，整數位第一個只能是“123456789”，
// 且后一位只能是“0123456789±/.!^)”中的一個。
//4.如果0到上一個運算符之間有一個“.”的話,則后一位只能是“0123456789±/.^)”中的一個
//7."123456789"后面只能是“0123456789±/.!^)”中的一個
//8."(“后面只能是“0123456789locstg()ep”中的一個
//9.”)"后面只能是“±/!^)”中的一個
//10.最后一位字符只能是“0123456789!)ep”中的一個
//12.不能有多個“.”
//13."ep"后面只能是“±*/^)”中的一個
除數不能為0
階乘必須為自然數
ln的x必須大于0
log的x必須大于0
tan的x不能為±(π/2 + kπ)
括號是否匹配

代碼如下：

public void estimate(){//判斷輸入是否錯誤
        int i = 0;
        if (str.length() == 0){
        }
        if (str.length() == 1){
            //當只有一位字符時，只能是“0123456789ep”中的一個
            if ("0123456789ep".indexOf(str.charAt(0)) == -1){
                jTextField1.setText("輸入錯誤！");
                indexYN = 1;
            }
        }
        if (str.length() > 1){
            for (i = 0; i < str.length() - 1; i++) {
                //1.第一個字符只能為"losctg(0123456789ep"中的一個
                if ("losctg(0123456789ep".indexOf(str.charAt(0)) == -1){
                    jTextField1.setText("輸入錯誤！");
                    indexYN = 1;
                }
                //2.“+-*/”后面只能是"0123456789losctg(ep"中的一個
                if ("+-*/".indexOf(str.charAt(i)) >= 0 && "0123456789losctg(ep".indexOf(str.charAt(i + 1)) == -1){
                    jTextField1.setText("輸入錯誤！");
                    indexYN = 1;
                }
                //3."."后面只能是“0123456789”中的一個
                if (str.charAt(i) == '.' && "0123456789".indexOf(str.charAt(i + 1)) == -1){
                    jTextField1.setText("輸入錯誤！");
                    indexYN = 1;
                }
                //4."!"后面只能是“+-*/^)”中的一個
                if (str.charAt(i) == '!' && "+-*/^)".indexOf(str.charAt(i + 1)) == -1){
                    jTextField1.setText("輸入錯誤！");
                    indexYN = 1;
                }
                //5."losctg"后面只能是“0123456789(ep”中的一個
                if ("losctg".indexOf(str.charAt(i)) >= 0 && "0123456789(ep".indexOf(str.charAt(i + 1)) == -1){
                    jTextField1.setText("輸入錯誤！");
                    indexYN = 1;
                }
                //6."0"的判斷操作
                if (str.charAt(0) == '0' && str.charAt(1) == '0'){
                    jTextField1.setText("輸入錯誤！");
                    indexYN = 1;
                }
                if (i >= 1 && str.charAt(i) == '0'){
                    //&& str.charAt(0) == '0' && str.charAt(1) == '0'
                    int m = i;
                    int n = i;
                    int is = 0;
                    //1.當0的上一個字符不為"0123456789."時，后一位只能是“+-*/.!^)”中的一個
                    if ("0123456789.".indexOf(str.charAt(m - 1)) == -1 && "+-*/.!^)".indexOf(str.charAt(i + 1)) == -1){
                        jTextField1.setText("輸入錯誤！");
                        indexYN = 1;
                    }
                    //2.如果0的上一位為“.”,則后一位只能是“0123456789+-*/.^)”中的一個
                    if (str.charAt(m - 1) == '.' && "0123456789+-*/.^)".indexOf(str.charAt(i + 1)) == -1){
                        jTextField1.setText("輸入錯誤！");
                        indexYN = 1;
                    }
                    n -= 1;
                    while (n > 0){
                        if ("(+-*/^glosct".indexOf(str.charAt(n)) >= 0){
                            break;
                        }
                        if (str.charAt(n) == '.'){
                            is++;
                        }
                        n--;
                    }

                    //3.如果0到上一個運算符之間沒有“.”的話，整數位第一個只能是“123456789”，
                    //  且后一位只能是“0123456789+-*/.!^)”中的一個。
                    if ((is == 0 && str.charAt(n) == '0') || "0123456789+-*/.!^)".indexOf(str.charAt(i + 1)) == -1){
                        jTextField1.setText("輸入錯誤！");
                        indexYN = 1;
                    }
                    //4.如果0到上一個運算符之間有一個“.”的話,則后一位只能是“0123456789+-*/.^)”中的一個
                    if (is == 1 && "0123456789+-*/.^)".indexOf(str.charAt(i + 1)) == -1){
                        jTextField1.setText("輸入錯誤！");
                        indexYN = 1;
                    }
                    if (is > 1){
                        jTextField1.setText("輸入錯誤！");
                        indexYN = 1;
                    }

                }
                //7."123456789"后面只能是“0123456789+-*/.!^)”中的一個
                if ("123456789".indexOf(str.charAt(i)) >= 0 && "0123456789+-*/.!^)".indexOf(str.charAt(i + 1)) == -1){
                    jTextField1.setText("輸入錯誤！");
                    indexYN = 1;
                }
                //8."("后面只能是“0123456789locstg()ep”中的一個
                if (str.charAt(i) == '(' && "0123456789locstg()ep".indexOf(str.charAt(i + 1)) == -1){
                    jTextField1.setText("輸入錯誤！");
                    indexYN = 1;
                }
                //9.")"后面只能是“+-*/!^)”中的一個
                if (str.charAt(i) == ')' && "+-*/!^)".indexOf(str.charAt(i + 1)) == -1){
                    jTextField1.setText("輸入錯誤！");
                    indexYN = 1;
                }
                //10.最后一位字符只能是“0123456789!)ep”中的一個
                if ("0123456789!)ep".indexOf(str.charAt(str.length() - 1)) == -1){
                    jTextField1.setText("輸入錯誤！");
                    indexYN = 1;
                }
                //12.不能有多個“.”
                if (i > 2 && str.charAt(i) == '.'){
                    int n = i - 1;
                    int is = 0;
                    while (n > 0){
                        if ("(+-*/^glosct".indexOf(str.charAt(n)) >= 0){
                            break;
                        }
                        if (str.charAt(n) == '.'){
                            is++;
                        }
                        n--;
                    }
                    if (is > 0){
                        jTextField1.setText("輸入錯誤！");
                        indexYN = 1;
                    }
                }
                //13."ep"后面只能是“+-*/^)”中的一個
                if ("ep".indexOf(str.charAt(i)) >= 0 && "+-*/^)".indexOf(str.charAt(i + 1)) == -1){
                    jTextField1.setText("輸入錯誤！");
                    indexYN = 1;
                }
            }
        }
    }

4.計算后綴表達式

代碼如下：

public double math(List<String> list2) {//通過后綴表達式進行計算
        Stack<String> stack = new Stack<String>();
        for (int i = 0; i < list2.size(); i++) {
            if (isNumber(list2.get(i))) {
                if (list2.get(i).charAt(0) == 'e'){
                    stack.push(String.valueOf(Math.E));
                } else if (list2.get(i).charAt(0) == 'p'){
                    stack.push(String.valueOf(Math.PI));
                } else {
                    stack.push(list2.get(i));
                }
            } else if (isOperator(list2.get(i))){
                double res = 0;
                if (list2.get(i).equals("+")) {
                    double num2 = Double.parseDouble(stack.pop());
                    double num1 = Double.parseDouble(stack.pop());
                    res = num1 + num2;
                } else if (list2.get(i).equals("-")) {
                    double num2 = Double.parseDouble(stack.pop());
                    double num1 = Double.parseDouble(stack.pop());
                    res = num1 - num2;
                } else if (list2.get(i).equals("*")) {
                    double num2 = Double.parseDouble(stack.pop());
                    double num1 = Double.parseDouble(stack.pop());
                    res = num1 * num2;
                } else if (list2.get(i).equals("/")) {
                    double num2 = Double.parseDouble(stack.pop());
                    double num1 = Double.parseDouble(stack.pop());
                    if (num2 != 0){
                        res = num1 / num2;
                    } else {
                        jTextField1.setText("除數不能為0");
                        indexYN = 1;
                    }
                } else if (list2.get(i).equals("^")) {
                    double num2 = Double.parseDouble(stack.pop());
                    double num1 = Double.parseDouble(stack.pop());
                    res = Math.pow(num1, num2);
                } else if (list2.get(i).equals("!")) {
                    double num1 = Double.parseDouble(stack.pop());
                    if (num1 == 0 || num1 == 1){
                        res = 1;
                    } else if (num1 == (int)num1 && num1 > 1){
                        int d = 1;
                        for (int j = (int)num1; j >0; j--) {
                            d *= j;
                        }
                        res = d;
                    } else {
                        jTextField1.setText("階乘必須為自然數");
                        indexYN = 1;
                    }
                } else if (list2.get(i).equals("g")) {
                    double num1 = Double.parseDouble(stack.pop());
                    res = Math.sqrt(num1);
                } else if (list2.get(i).equals("l")) {
                    double num1 = Double.parseDouble(stack.pop());
                    if (num1 > 0){
                        res = Math.log(num1);
                    } else {
                        jTextField1.setText("ln的x必須大于0");
                        indexYN = 1;
                    }
                } else if (list2.get(i).equals("o")) {
                    double num1 = Double.parseDouble(stack.pop());
                    if (num1 > 0){
                        res = Math.log(num1) / Math.log(2);
                    } else {
                        jTextField1.setText("log的x必須大于0");
                        indexYN = 1;
                    }
                } else if (list2.get(i).equals("s")) {
                    double num1 = Double.parseDouble(stack.pop());
                    res = Math.sin(num1);
                } else if (list2.get(i).equals("c")) {
                    double num1 = Double.parseDouble(stack.pop());
                    res = Math.cos(num1);
                } else if (list2.get(i).equals("t")) {
                    double num1 = Double.parseDouble(stack.pop());
                    if (Math.cos(num1) != 0){
                        res = Math.tan(num1);
                    } else {
                        jTextField1.setText("tan的x不能為+-(π/2 + kπ)");
                        indexYN = 1;
                    }
                }
                stack.push("" + res);
            }
        }
        if (indexYN == 0){
            if (!stack.isEmpty()){
                return Double.parseDouble(stack.pop());
            } else {
                return 0;
            }
        } else {
            return -999999;
        }
    }

    public void zhanDui(){//進行計算，并且判斷括號是否匹配
        String khao = "";
        int leftkh = 0;
        int rightkh = 0;
        int m = 0;
        //判斷括號是否成對
        for (int i = 0; i < str.length(); i++) {
            if (str.charAt(i) == '('){
                khao += '(';
                leftkh++;
            }
            if (str.charAt(i) == ')'){
                khao += ')';
                rightkh++;
            }
        }
        if (leftkh != rightkh){
            jTextField1.setText("輸入錯誤！括號不匹配");
            indexYN = 1;
        }
        if ((leftkh == 0 && rightkh == 0) || ((leftkh == rightkh && leftkh > 0) && khao.charAt(0) == '(' && khao.charAt(khao.length() - 1) == ')')){
            if (indexYN == 0){
                List<String> list1 = zhongZhui(str);
                //System.out.println(list1);
                List<String> list2 = houZhui(list1);
                //System.out.println(list2);
                if (indexYN == 0){
                    if (math(list2) == -999999){
                        jTextField1.setText(jTextField1.getText());
                    } else {
                        jTextField1.setText(String.valueOf(math(list2)));
                        jTextField2.setText(String.valueOf(math(list2)));
                        jTextField2.setText(String.valueOf(math(list2)));
                    }
                }
            }
        } else {
            jTextField1.setText("輸入錯誤！括號不匹配");
            indexYN = 1;
        }
    }

5.事件監聽器

因為設置了33個按鈕，所以每個按鈕都要設計事件監聽器，我設置的目的是把點中的按鈕的值寫入到文本框中輸出，并且把它代表的數值或者操作符存放到字符串中，以便于進行中綴轉后綴和運算。

代碼如下：

public void buttonLister(){//事件監聽器
     int tep = 0;
     buttons[tep++].addActionListener(new ActionListener() {
         @Override
         public void actionPerformed(ActionEvent e) {
             jTextField1.setText(jTextField1.getText() + "(");
             str += "(";
         }
     });
     buttons[tep++].addActionListener(new ActionListener() {
         @Override
         public void actionPerformed(ActionEvent e) {
             jTextField1.setText(jTextField1.getText() + ")");
             str += ")";
         }
     });
     buttons[tep++].addActionListener(new ActionListener() {
         @Override
         public void actionPerformed(ActionEvent e) {
             jTextField1.setText(jTextField1.getText() + "1/");
             str += "1/";
         }
     });
     buttons[tep++].addActionListener(new ActionListener() {
         @Override
         public void actionPerformed(ActionEvent e) {
             jTextField1.setText(jTextField1.getText() + "^2");
             str += "^2";
         }
     });
     buttons[tep++].addActionListener(new ActionListener() {
         @Override
         public void actionPerformed(ActionEvent e) {
             jTextField1.setText(jTextField1.getText() + "^3");
             str += "^3";
         }
     });
     buttons[tep++].addActionListener(new ActionListener() {
         @Override
         public void actionPerformed(ActionEvent e) {
             jTextField1.setText(jTextField1.getText() + "^");
             str += "^";
         }
     });

     buttons[tep++].addActionListener(new ActionListener() {
         @Override
         public void actionPerformed(ActionEvent e) {
             jTextField1.setText(jTextField1.getText() + "!");
             str += "!";
         }
     });
     buttons[tep++].addActionListener(new ActionListener() {
         @Override
         public void actionPerformed(ActionEvent e) {
             jTextField1.setText(jTextField1.getText() + "√");
             str += "g";
         }
     });
     buttons[tep++].addActionListener(new ActionListener() {
         @Override
         public void actionPerformed(ActionEvent e) {
             jTextField1.setText(jTextField1.getText() + "e");
             str += "e";
             //str += "2.7182818284590452354";
         }
     });
     buttons[tep++].addActionListener(new ActionListener() {
         @Override
         public void actionPerformed(ActionEvent e) {
             jTextField1.setText(jTextField1.getText() + "ln");
             str += "l";
         }
     });
     buttons[tep++].addActionListener(new ActionListener() {
         @Override
         public void actionPerformed(ActionEvent e) {
             jTextField1.setText(jTextField1.getText() + "log");
             str += "o";
         }
     });
     buttons[tep++].addActionListener(new ActionListener() {
         @Override
         public void actionPerformed(ActionEvent e) {
             jTextField1.setText(jTextField1.getText() + "%");
             str += "*0.01";
         }
     });

     buttons[tep++].addActionListener(new ActionListener() {
         @Override
         public void actionPerformed(ActionEvent e) {
             jTextField1.setText(jTextField1.getText() + "sin");
             str += "s";
         }
     });
     buttons[tep++].addActionListener(new ActionListener() {
         @Override
         public void actionPerformed(ActionEvent e) {
             jTextField1.setText(jTextField1.getText() + "cos");
             str += "c";
         }
     });
     buttons[tep++].addActionListener(new ActionListener() {
         @Override
         public void actionPerformed(ActionEvent e) {
             jTextField1.setText(jTextField1.getText() + "tan");
             str += "t";
         }
     });
     buttons[tep++].addActionListener(new ActionListener() {
         @Override
         public void actionPerformed(ActionEvent e) {
             jTextField1.setText(jTextField1.getText() + "π");
             str += "p";
         }
     });
     buttons[tep++].addActionListener(new ActionListener() {
         @Override
         public void actionPerformed(ActionEvent e) {
             jTextField1.setText(jTextField1.getText() + "+");
             str += "+";
         }
     });
     buttons[tep++].addActionListener(new ActionListener() {
         @Override
         public void actionPerformed(ActionEvent e) {
             if (str != ""){
                 estimate();
                 zhanDui();
             } else {
                 str = "";
             }
         }
     });

     buttons[tep++].addActionListener(new ActionListener() {
         @Override
         public void actionPerformed(ActionEvent e) {
             jTextField1.setText(jTextField1.getText() + "7");
             str += "7";
         }
     });
     buttons[tep++].addActionListener(new ActionListener() {
         @Override
         public void actionPerformed(ActionEvent e) {
             jTextField1.setText(jTextField1.getText() + "8");
             str += "8";
         }
     });
     buttons[tep++].addActionListener(new ActionListener() {
         @Override
         public void actionPerformed(ActionEvent e) {
             jTextField1.setText(jTextField1.getText() + "9");
             str += "9";
         }
     });
     buttons[tep++].addActionListener(new ActionListener() {
         @Override
         public void actionPerformed(ActionEvent e) {
             jTextField1.setText(jTextField1.getText() + "0");
             str += "0";
         }
     });
     buttons[tep++].addActionListener(new ActionListener() {
         @Override
         public void actionPerformed(ActionEvent e) {
             jTextField1.setText(jTextField1.getText() + "-");
             str += "-";
         }
     });

     buttons[tep++].addActionListener(new ActionListener() {
         @Override
         public void actionPerformed(ActionEvent e) {
             jTextField1.setText(jTextField1.getText() + "4");
             str += "4";
         }
     });
     buttons[tep++].addActionListener(new ActionListener() {
         @Override
         public void actionPerformed(ActionEvent e) {
             jTextField1.setText(jTextField1.getText() + "5");
             str += "5";
         }
     });
     buttons[tep++].addActionListener(new ActionListener() {
         @Override
         public void actionPerformed(ActionEvent e) {
             jTextField1.setText(jTextField1.getText() + "6");
             str += "6";
         }
     });
     buttons[tep++].addActionListener(new ActionListener() {
         @Override
         public void actionPerformed(ActionEvent e) {
             jTextField1.setText(jTextField1.getText() + ".");
             str += ".";
         }
     });
     buttons[tep++].addActionListener(new ActionListener() {
         @Override
         public void actionPerformed(ActionEvent e) {
             jTextField1.setText(jTextField1.getText() + "*");
             str += "*";
         }
     });

     buttons[tep++].addActionListener(new ActionListener() {
         @Override
         public void actionPerformed(ActionEvent e) {
             jTextField1.setText(jTextField1.getText() + "1");
             str += "1";
         }
     });
     buttons[tep++].addActionListener(new ActionListener() {
         @Override
         public void actionPerformed(ActionEvent e) {
             jTextField1.setText(jTextField1.getText() + "2");
             str += "2";
         }
     });
     buttons[tep++].addActionListener(new ActionListener() {
         @Override
         public void actionPerformed(ActionEvent e) {
             jTextField1.setText(jTextField1.getText() + "3");
             str += "3";
         }
     });
     buttons[tep++].addActionListener(new ActionListener() {
         @Override
         public void actionPerformed(ActionEvent e) {
             jTextField1.setText("");
             str = "";
             indexYN = 0;
         }
     });
     buttons[tep].addActionListener(new ActionListener() {
         @Override
         public void actionPerformed(ActionEvent e) {
             jTextField1.setText(jTextField1.getText() + "÷");
             str += "/";
         }
     });
 }

完整代碼

直接拷貝到Java中就可以用：

一個類走完程序。

main函數中還可以設置面板風格。有

• Niumbus風格

• Windows風格

• Windows經典風格

三種風格可以自定義選擇，我個人覺得Niumbus風格比較好看。選擇哪一個就釋放哪一個，把另外兩個注釋掉就可以了。

package com.lmdxyt;

import javax.swing.*;
import javax.swing.plaf.FontUIResource;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.util.ArrayList;
import java.util.List;
import java.util.Stack;

public class JSQ {
 private JFrame jFrame = new JFrame("計算器");
 private FontUIResource f = new FontUIResource("隸書", 1, 20);
 private FontUIResource f1 = new FontUIResource("楷書", 0, 35);
 private JPanel jPanel = new JPanel();
 private int buttonx = 100;
 private int buttony = 50;
 private int yy = 50;
 private JTextField jTextField1 = new JTextField("0", 30);
 private JTextField jTextField2 = new JTextField("輸入要求在main()中", 30);
 private String str = "";
 private String temp = "";
 private int indexYN = 0;
 private String[] strings = {
         "(", ")", "1/x", "x^2", "x^3", "x^y",
         "x!", "√", "e", "ln", "log", "%",
         "sin", "cos", "tan", "π", "+", "=",
         "7", "8", "9", "0", "-",
         "4", "5", "6", ".", "*",
         "1", "2", "3", "c", "÷"
 };
 private JButton[] buttons = new JButton[33];

 public void loAsi(){
     int tep = 0;
     for (int i = 0; i < 3; i++) {
         for (int j = 0; j < 6; j++) {
             buttons[tep] = new JButton(strings[tep]);
             buttons[tep].setFont(f);
             buttons[tep++].setFocusable(false);
         }
     }
     for (int i = 0; i < 3; i++) {
         for (int j = 0; j < 5; j++) {
             buttons[tep] = new JButton(strings[tep]);
             buttons[tep].setFont(f);
             buttons[tep++].setFocusable(false);
         }
     }
     int lo = 0;
     for (int i = 0; i < 2; i++) {
         for (int j = 0; j < 6; j++) {
             buttons[lo++].setBounds(buttonx * j, yy * (2 + i), buttonx, buttony);
         }
     }
     for (int i = 0; i < 5; i++) {
         buttons[lo++].setBounds(buttonx * i, yy * 4, buttonx, buttony);
     }
     buttons[lo++].setBounds(buttonx * 5, yy * 4, buttonx, buttony * 4);
     for (int i = 0; i < 3; i++) {
         for (int j = 0; j < 5; j++) {
             buttons[lo++].setBounds(buttonx * j, yy * (5 + i), buttonx, buttony);
         }
     }
     jTextField1.setBounds(0, yy, 600, yy);
     jTextField1.setFont(f1);
     jTextField1.setHorizontalAlignment(JLabel.RIGHT);
     jTextField1.setEditable(false);
     jTextField1.setBackground(Color.WHITE);
     jTextField2.setBounds(0, 0, 600, yy);
     jTextField2.setFont(f1);
     jTextField2.setHorizontalAlignment(JLabel.RIGHT);
     jTextField2.setEditable(false);
     jTextField2.setBackground(Color.WHITE);
 }
 public void initButton(){//把按鈕添加到jPanel中
     this.loAsi();
     jPanel.add(jTextField1);
     jPanel.add(jTextField2);
     for (int i = 0; i < buttons.length; i++) {
         jPanel.add(buttons[i]);
     }
     jPanel.setLayout(null);
 }

 private List<String> zhongZhui(String str) {//把輸入的字符串轉換成中綴表達式。存入list中
     int index = 0;
     List<String> list = new ArrayList<>();
     do{
         char ch = str.charAt(index);
         if("+-*/^!logsct()".indexOf(str.charAt(index)) >= 0){
             //是操作符，直接添加至list中
             index ++;
             list.add(ch+"");
         }else if (str.charAt(index) == 'e' || str.charAt(index) == 'p'){
             index ++;
             list.add(ch+"");
         } else if("0123456789".indexOf(str.charAt(index)) >= 0){
             //是數字,判斷多位數的情況
             String str1 = "";
             while (index < str.length() && "0123456789.".indexOf(str.charAt(index)) >= 0){
                 str1 += str.charAt(index);
                 index ++;
             }
             list.add(str1);

         }
     }while (index < str.length());
     return list;
 }

 public List<String> houZhui(List<String> list){//中綴表達式轉換稱后綴表達式
     Stack<String> fuZhan = new Stack<>();
     List<String> list2 = new ArrayList<>();
     if (!list.isEmpty()) {
         for (int i = 0; i < list.size(); i++) {
             if (isNumber(list.get(i))){
                 list2.add(list.get(i));
             } else if (list.get(i).charAt(0) == '('){
                 fuZhan.push(list.get(i));
             } else if (isOperator(list.get(i)) && list.get(i).charAt(0) != '('){
                 if (fuZhan.isEmpty()){
                     fuZhan.push(list.get(i));
                 } else {//符棧不為空
                     if (list.get(i).charAt(0) != ')'){
                         if (adv(fuZhan.peek()) <= adv(list.get(i))){
                             //入棧
                             fuZhan.push(list.get(i));
                         } else {//出棧
                             while (!fuZhan.isEmpty() && !"(".equals(fuZhan.peek())){
                                 if(adv(list.get(i)) <= adv(fuZhan.peek())){
                                     list2.add(fuZhan.pop());
                                 }
                             }
                             if (fuZhan.isEmpty() || fuZhan.peek().charAt(0) == '('){
                                 fuZhan.push(list.get(i));
                             }
                         }
                     } else if (list.get(i).charAt(0) == ')'){
                         while (fuZhan.peek().charAt(0) != '('){
                             list2.add(fuZhan.pop());
                         }
                         fuZhan.pop();
                     }
                 }
             }
         }
         while (!fuZhan.isEmpty()){
             list2.add(fuZhan.pop());
         }
     } else {
         jTextField1.setText("");
     }
     return list2;
 }
 public static boolean isOperator(String op){//判斷是否為操作符
     if ("0123456789.ep".indexOf(op.charAt(0)) == -1) {
         return true;
     } else {
         return false;
     }
 }
 public static boolean isNumber(String num){//判斷是否為操作數
     if ("0123456789ep".indexOf(num.charAt(0)) >= 0) {
         return true;
     } else {
         return false;
     }
 }
 public static int adv(String f){//判斷操作符的優先級
     int result = 0;
     switch(f) {
         case "+":
             result = 1;
             break;
         case "-":
             result = 1;
             break;
         case "*":
             result = 2;
             break;
         case "/":
             result = 2;
             break;
         case "^":
             result = 3;
             break;
         case "!":
             result = 4;
             break;
         case "g":
             result = 4;
             break;
         case "l":
             result = 4;
             break;
         case "o":
             result = 4;
             break;
         case "s":
             result = 4;
             break;
         case "c":
             result = 4;
             break;
         case "t":
             result = 4;
             break;

     }
     return result;
 }

 public void buttonLister(){//事件監聽器
     int tep = 0;
     buttons[tep++].addActionListener(new ActionListener() {
         @Override
         public void actionPerformed(ActionEvent e) {
             jTextField1.setText(jTextField1.getText() + "(");
             str += "(";
         }
     });
     buttons[tep++].addActionListener(new ActionListener() {
         @Override
         public void actionPerformed(ActionEvent e) {
             jTextField1.setText(jTextField1.getText() + ")");
             str += ")";
         }
     });
     buttons[tep++].addActionListener(new ActionListener() {
         @Override
         public void actionPerformed(ActionEvent e) {
             jTextField1.setText(jTextField1.getText() + "1/");
             str += "1/";
         }
     });
     buttons[tep++].addActionListener(new ActionListener() {
         @Override
         public void actionPerformed(ActionEvent e) {
             jTextField1.setText(jTextField1.getText() + "^2");
             str += "^2";
         }
     });
     buttons[tep++].addActionListener(new ActionListener() {
         @Override
         public void actionPerformed(ActionEvent e) {
             jTextField1.setText(jTextField1.getText() + "^3");
             str += "^3";
         }
     });
     buttons[tep++].addActionListener(new ActionListener() {
         @Override
         public void actionPerformed(ActionEvent e) {
             jTextField1.setText(jTextField1.getText() + "^");
             str += "^";
         }
     });

     buttons[tep++].addActionListener(new ActionListener() {
         @Override
         public void actionPerformed(ActionEvent e) {
             jTextField1.setText(jTextField1.getText() + "!");
             str += "!";
         }
     });
     buttons[tep++].addActionListener(new ActionListener() {
         @Override
         public void actionPerformed(ActionEvent e) {
             jTextField1.setText(jTextField1.getText() + "√");
             str += "g";
         }
     });
     buttons[tep++].addActionListener(new ActionListener() {
         @Override
         public void actionPerformed(ActionEvent e) {
             jTextField1.setText(jTextField1.getText() + "e");
             str += "e";
             //str += "2.7182818284590452354";
         }
     });
     buttons[tep++].addActionListener(new ActionListener() {
         @Override
         public void actionPerformed(ActionEvent e) {
             jTextField1.setText(jTextField1.getText() + "ln");
             str += "l";
         }
     });
     buttons[tep++].addActionListener(new ActionListener() {
         @Override
         public void actionPerformed(ActionEvent e) {
             jTextField1.setText(jTextField1.getText() + "log");
             str += "o";
         }
     });
     buttons[tep++].addActionListener(new ActionListener() {
         @Override
         public void actionPerformed(ActionEvent e) {
             jTextField1.setText(jTextField1.getText() + "%");
             str += "*0.01";
         }
     });

     buttons[tep++].addActionListener(new ActionListener() {
         @Override
         public void actionPerformed(ActionEvent e) {
             jTextField1.setText(jTextField1.getText() + "sin");
             str += "s";
         }
     });
     buttons[tep++].addActionListener(new ActionListener() {
         @Override
         public void actionPerformed(ActionEvent e) {
             jTextField1.setText(jTextField1.getText() + "cos");
             str += "c";
         }
     });
     buttons[tep++].addActionListener(new ActionListener() {
         @Override
         public void actionPerformed(ActionEvent e) {
             jTextField1.setText(jTextField1.getText() + "tan");
             str += "t";
         }
     });
     buttons[tep++].addActionListener(new ActionListener() {
         @Override
         public void actionPerformed(ActionEvent e) {
             jTextField1.setText(jTextField1.getText() + "π");
             str += "p";
         }
     });
     buttons[tep++].addActionListener(new ActionListener() {
         @Override
         public void actionPerformed(ActionEvent e) {
             jTextField1.setText(jTextField1.getText() + "+");
             str += "+";
         }
     });
     buttons[tep++].addActionListener(new ActionListener() {
         @Override
         public void actionPerformed(ActionEvent e) {
             if (str != ""){
                 estimate();
                 zhanDui();
             } else {
                 str = "";
             }
         }
     });

     buttons[tep++].addActionListener(new ActionListener() {
         @Override
         public void actionPerformed(ActionEvent e) {
             jTextField1.setText(jTextField1.getText() + "7");
             str += "7";
         }
     });
     buttons[tep++].addActionListener(new ActionListener() {
         @Override
         public void actionPerformed(ActionEvent e) {
             jTextField1.setText(jTextField1.getText() + "8");
             str += "8";
         }
     });
     buttons[tep++].addActionListener(new ActionListener() {
         @Override
         public void actionPerformed(ActionEvent e) {
             jTextField1.setText(jTextField1.getText() + "9");
             str += "9";
         }
     });
     buttons[tep++].addActionListener(new ActionListener() {
         @Override
         public void actionPerformed(ActionEvent e) {
             jTextField1.setText(jTextField1.getText() + "0");
             str += "0";
         }
     });
     buttons[tep++].addActionListener(new ActionListener() {
         @Override
         public void actionPerformed(ActionEvent e) {
             jTextField1.setText(jTextField1.getText() + "-");
             str += "-";
         }
     });

     buttons[tep++].addActionListener(new ActionListener() {
         @Override
         public void actionPerformed(ActionEvent e) {
             jTextField1.setText(jTextField1.getText() + "4");
             str += "4";
         }
     });
     buttons[tep++].addActionListener(new ActionListener() {
         @Override
         public void actionPerformed(ActionEvent e) {
             jTextField1.setText(jTextField1.getText() + "5");
             str += "5";
         }
     });
     buttons[tep++].addActionListener(new ActionListener() {
         @Override
         public void actionPerformed(ActionEvent e) {
             jTextField1.setText(jTextField1.getText() + "6");
             str += "6";
         }
     });
     buttons[tep++].addActionListener(new ActionListener() {
         @Override
         public void actionPerformed(ActionEvent e) {
             jTextField1.setText(jTextField1.getText() + ".");
             str += ".";
         }
     });
     buttons[tep++].addActionListener(new ActionListener() {
         @Override
         public void actionPerformed(ActionEvent e) {
             jTextField1.setText(jTextField1.getText() + "*");
             str += "*";
         }
     });

     buttons[tep++].addActionListener(new ActionListener() {
         @Override
         public void actionPerformed(ActionEvent e) {
             jTextField1.setText(jTextField1.getText() + "1");
             str += "1";
         }
     });
     buttons[tep++].addActionListener(new ActionListener() {
         @Override
         public void actionPerformed(ActionEvent e) {
             jTextField1.setText(jTextField1.getText() + "2");
             str += "2";
         }
     });
     buttons[tep++].addActionListener(new ActionListener() {
         @Override
         public void actionPerformed(ActionEvent e) {
             jTextField1.setText(jTextField1.getText() + "3");
             str += "3";
         }
     });
     buttons[tep++].addActionListener(new ActionListener() {
         @Override
         public void actionPerformed(ActionEvent e) {
             jTextField1.setText("");
             str = "";
             indexYN = 0;
         }
     });
     buttons[tep].addActionListener(new ActionListener() {
         @Override
         public void actionPerformed(ActionEvent e) {
             jTextField1.setText(jTextField1.getText() + "÷");
             str += "/";
         }
     });
 }

 public void init(){
     this.initButton();
     this.buttonLister();
     jFrame.add(jPanel);
     jFrame.setSize(614, 437);
     jFrame.setResizable(false);
     jFrame.setLocationRelativeTo(null);
     jFrame.addWindowListener(new WindowAdapter() {
         @Override
         public void windowClosing(WindowEvent e) {
             System.exit(0);
         }
     });
     jFrame.setVisible(true);
 }
 public void estimate(){//判斷輸入是否錯誤
     int i = 0;
     if (str.length() == 0){
     }
     if (str.length() == 1){
         //當只有一位字符時，只能是“0123456789ep”中的一個
         if ("0123456789ep".indexOf(str.charAt(0)) == -1){
             jTextField1.setText("輸入錯誤！");
             indexYN = 1;
         }
     }
     if (str.length() > 1){
         for (i = 0; i < str.length() - 1; i++) {
             //1.第一個字符只能為"losctg(0123456789ep"中的一個
             if ("losctg(0123456789ep".indexOf(str.charAt(0)) == -1){
                 jTextField1.setText("輸入錯誤！");
                 indexYN = 1;
             }
             //2.“+-*/”后面只能是"0123456789losctg(ep"中的一個
             if ("+-*/".indexOf(str.charAt(i)) >= 0 && "0123456789losctg(ep".indexOf(str.charAt(i + 1)) == -1){
                 jTextField1.setText("輸入錯誤！");
                 indexYN = 1;
             }
             //3."."后面只能是“0123456789”中的一個
             if (str.charAt(i) == '.' && "0123456789".indexOf(str.charAt(i + 1)) == -1){
                 jTextField1.setText("輸入錯誤！");
                 indexYN = 1;
             }
             //4."!"后面只能是“+-*/^)”中的一個
             if (str.charAt(i) == '!' && "+-*/^)".indexOf(str.charAt(i + 1)) == -1){
                 jTextField1.setText("輸入錯誤！");
                 indexYN = 1;
             }
             //5."losctg"后面只能是“0123456789(ep”中的一個
             if ("losctg".indexOf(str.charAt(i)) >= 0 && "0123456789(ep".indexOf(str.charAt(i + 1)) == -1){
                 jTextField1.setText("輸入錯誤！");
                 indexYN = 1;
             }
             //6."0"的判斷操作
             if (str.charAt(0) == '0' && str.charAt(1) == '0'){
                 jTextField1.setText("輸入錯誤！");
                 indexYN = 1;
             }
             if (i >= 1 && str.charAt(i) == '0'){
                 //&& str.charAt(0) == '0' && str.charAt(1) == '0'
                 int m = i;
                 int n = i;
                 int is = 0;
                 //1.當0的上一個字符不為"0123456789."時，后一位只能是“+-*/.!^)”中的一個
                 if ("0123456789.".indexOf(str.charAt(m - 1)) == -1 && "+-*/.!^)".indexOf(str.charAt(i + 1)) == -1){
                     jTextField1.setText("輸入錯誤！");
                     indexYN = 1;
                 }
                 //2.如果0的上一位為“.”,則后一位只能是“0123456789+-*/.^)”中的一個
                 if (str.charAt(m - 1) == '.' && "0123456789+-*/.^)".indexOf(str.charAt(i + 1)) == -1){
                     jTextField1.setText("輸入錯誤！");
                     indexYN = 1;
                 }
                 n -= 1;
                 while (n > 0){
                     if ("(+-*/^glosct".indexOf(str.charAt(n)) >= 0){
                         break;
                     }
                     if (str.charAt(n) == '.'){
                         is++;
                     }
                     n--;
                 }

                 //3.如果0到上一個運算符之間沒有“.”的話，整數位第一個只能是“123456789”，
                 //  且后一位只能是“0123456789+-*/.!^)”中的一個。
                 if ((is == 0 && str.charAt(n) == '0') || "0123456789+-*/.!^)".indexOf(str.charAt(i + 1)) == -1){
                     jTextField1.setText("輸入錯誤！");
                     indexYN = 1;
                 }
                 //4.如果0到上一個運算符之間有一個“.”的話,則后一位只能是“0123456789+-*/.^)”中的一個
                 if (is == 1 && "0123456789+-*/.^)".indexOf(str.charAt(i + 1)) == -1){
                     jTextField1.setText("輸入錯誤！");
                     indexYN = 1;
                 }
                 if (is > 1){
                     jTextField1.setText("輸入錯誤！");
                     indexYN = 1;
                 }

             }
             //7."123456789"后面只能是“0123456789+-*/.!^)”中的一個
             if ("123456789".indexOf(str.charAt(i)) >= 0 && "0123456789+-*/.!^)".indexOf(str.charAt(i + 1)) == -1){
                 jTextField1.setText("輸入錯誤！");
                 indexYN = 1;
             }
             //8."("后面只能是“0123456789locstg()ep”中的一個
             if (str.charAt(i) == '(' && "0123456789locstg()ep".indexOf(str.charAt(i + 1)) == -1){
                 jTextField1.setText("輸入錯誤！");
                 indexYN = 1;
             }
             //9.")"后面只能是“+-*/!^)”中的一個
             if (str.charAt(i) == ')' && "+-*/!^)".indexOf(str.charAt(i + 1)) == -1){
                 jTextField1.setText("輸入錯誤！");
                 indexYN = 1;
             }
             //10.最后一位字符只能是“0123456789!)ep”中的一個
             if ("0123456789!)ep".indexOf(str.charAt(str.length() - 1)) == -1){
                 jTextField1.setText("輸入錯誤！");
                 indexYN = 1;
             }
             //12.不能有多個“.”
             if (i > 2 && str.charAt(i) == '.'){
                 int n = i - 1;
                 int is = 0;
                 while (n > 0){
                     if ("(+-*/^glosct".indexOf(str.charAt(n)) >= 0){
                         break;
                     }
                     if (str.charAt(n) == '.'){
                         is++;
                     }
                     n--;
                 }
                 if (is > 0){
                     jTextField1.setText("輸入錯誤！");
                     indexYN = 1;
                 }
             }
             //13."ep"后面只能是“+-*/^)”中的一個
             if ("ep".indexOf(str.charAt(i)) >= 0 && "+-*/^)".indexOf(str.charAt(i + 1)) == -1){
                 jTextField1.setText("輸入錯誤！");
                 indexYN = 1;
             }
         }
     }
 }
 public double math(List<String> list2) {//通過后綴表達式進行計算
     Stack<String> stack = new Stack<String>();
     for (int i = 0; i < list2.size(); i++) {
         if (isNumber(list2.get(i))) {
             if (list2.get(i).charAt(0) == 'e'){
                 stack.push(String.valueOf(Math.E));
             } else if (list2.get(i).charAt(0) == 'p'){
                 stack.push(String.valueOf(Math.PI));
             } else {
                 stack.push(list2.get(i));
             }
         } else if (isOperator(list2.get(i))){
             double res = 0;
             if (list2.get(i).equals("+")) {
                 double num2 = Double.parseDouble(stack.pop());
                 double num1 = Double.parseDouble(stack.pop());
                 res = num1 + num2;
             } else if (list2.get(i).equals("-")) {
                 double num2 = Double.parseDouble(stack.pop());
                 double num1 = Double.parseDouble(stack.pop());
                 res = num1 - num2;
             } else if (list2.get(i).equals("*")) {
                 double num2 = Double.parseDouble(stack.pop());
                 double num1 = Double.parseDouble(stack.pop());
                 res = num1 * num2;
             } else if (list2.get(i).equals("/")) {
                 double num2 = Double.parseDouble(stack.pop());
                 double num1 = Double.parseDouble(stack.pop());
                 if (num2 != 0){
                     res = num1 / num2;
                 } else {
                     jTextField1.setText("除數不能為0");
                     indexYN = 1;
                 }
             } else if (list2.get(i).equals("^")) {
                 double num2 = Double.parseDouble(stack.pop());
                 double num1 = Double.parseDouble(stack.pop());
                 res = Math.pow(num1, num2);
             } else if (list2.get(i).equals("!")) {
                 double num1 = Double.parseDouble(stack.pop());
                 if (num1 == 0 || num1 == 1){
                     res = 1;
                 } else if (num1 == (int)num1 && num1 > 1){
                     int d = 1;
                     for (int j = (int)num1; j >0; j--) {
                         d *= j;
                     }
                     res = d;
                 } else {
                     jTextField1.setText("階乘必須為自然數");
                     indexYN = 1;
                 }
             } else if (list2.get(i).equals("g")) {
                 double num1 = Double.parseDouble(stack.pop());
                 res = Math.sqrt(num1);
             } else if (list2.get(i).equals("l")) {
                 double num1 = Double.parseDouble(stack.pop());
                 if (num1 > 0){
                     res = Math.log(num1);
                 } else {
                     jTextField1.setText("ln的x必須大于0");
                     indexYN = 1;
                 }
             } else if (list2.get(i).equals("o")) {
                 double num1 = Double.parseDouble(stack.pop());
                 if (num1 > 0){
                     res = Math.log(num1) / Math.log(2);
                 } else {
                     jTextField1.setText("log的x必須大于0");
                     indexYN = 1;
                 }
             } else if (list2.get(i).equals("s")) {
                 double num1 = Double.parseDouble(stack.pop());
                 res = Math.sin(num1);
             } else if (list2.get(i).equals("c")) {
                 double num1 = Double.parseDouble(stack.pop());
                 res = Math.cos(num1);
             } else if (list2.get(i).equals("t")) {
                 double num1 = Double.parseDouble(stack.pop());
                 if (Math.cos(num1) != 0){
                     res = Math.tan(num1);
                 } else {
                     jTextField1.setText("tan的x不能為+-(π/2 + kπ)");
                     indexYN = 1;
                 }
             }
             stack.push("" + res);
         }
     }
     if (indexYN == 0){
         if (!stack.isEmpty()){
             return Double.parseDouble(stack.pop());
         } else {
             return 0;
         }
     } else {
         return -999999;
     }
 }

 public void zhanDui(){//進行計算，并且判斷括號是否匹配
     String khao = "";
     int leftkh = 0;
     int rightkh = 0;
     int m = 0;
     //判斷括號是否成對
     for (int i = 0; i < str.length(); i++) {
         if (str.charAt(i) == '('){
             khao += '(';
             leftkh++;
         }
         if (str.charAt(i) == ')'){
             khao += ')';
             rightkh++;
         }
     }
     if (leftkh != rightkh){
         jTextField1.setText("輸入錯誤！括號不匹配");
         indexYN = 1;
     }
     if ((leftkh == 0 && rightkh == 0) || ((leftkh == rightkh && leftkh > 0) && khao.charAt(0) == '(' && khao.charAt(khao.length() - 1) == ')')){
         if (indexYN == 0){
             List<String> list1 = zhongZhui(str);
             //System.out.println(list1);
             List<String> list2 = houZhui(list1);
             //System.out.println(list2);
             if (indexYN == 0){
                 if (math(list2) == -999999){
                     jTextField1.setText(jTextField1.getText());
                 } else {
                     jTextField1.setText(String.valueOf(math(list2)));
                     jTextField2.setText(String.valueOf(math(list2)));
                     jTextField2.setText(String.valueOf(math(list2)));
                 }
             }
         }
     } else {
         jTextField1.setText("輸入錯誤！括號不匹配");
         indexYN = 1;
     }
 }

 public static void main(String[] args) {
     /*
      * 1.在輸入過程中每兩個數值之間必須有運算符，否則報錯.
      * 例如：錯誤：2ln4(5+8), 2sin2 等
      *      正確：2*ln4*(5+8)， 2*sin2
      * 2.不支持負數，要想得到負數，只能0-x
      * 例如：錯誤：-2+3*(-2*6)
      *      正確：0-2+3*((0-2)+6)
      * */
     new JSQ().init();
     //Niumbus風格
     try {
         UIManager.setLookAndFeel("javax.swing.plaf.nimbus.NimbusLookAndFeel");
     } catch (ClassNotFoundException ex) {
         ex.printStackTrace();
     } catch (InstantiationException ex) {
         ex.printStackTrace();
     } catch (IllegalAccessException ex) {
         ex.printStackTrace();
     } catch (UnsupportedLookAndFeelException ex) {
         ex.printStackTrace();
     }
     /*//Windows風格
     try {
         UIManager.setLookAndFeel("com.sun.java.swing.plaf.windows.WindowsLookAndFeel");
     } catch (ClassNotFoundException ex) {
         ex.printStackTrace();
     } catch (InstantiationException ex) {
         ex.printStackTrace();
     } catch (IllegalAccessException ex) {
         ex.printStackTrace();
     } catch (UnsupportedLookAndFeelException ex) {
         ex.printStackTrace();
     }*/
    /* //Windows經典風格
     try {
         UIManager.setLookAndFeel("com.sun.java.swing.plaf.windows.WindowsClassicLookAndFeel");
     } catch (ClassNotFoundException ex) {
         ex.printStackTrace();
     } catch (InstantiationException ex) {
         ex.printStackTrace();
     } catch (IllegalAccessException ex) {
         ex.printStackTrace();
     } catch (UnsupportedLookAndFeelException ex) {
         ex.printStackTrace();
     }*/
 }
}

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