【JavaGUI怎么设计计算器界面】

import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.*;

/**
 * GUI设计进阶+事件处理
 * 时间：2019.11.13
 * 完成人：梁达林
 */
public class Main {
    public static void main(String[] args) {
        Calculator calculator = new Calculator();
    }
}

class Calculator extends JFrame {
    private double result = 0;
    private int count = 0;

    public Calculator() {
        this.setSize(330, 399);
        this.setTitle("计算器");
        init();
        this.setVisible(true);
        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    }

    public void init() {
        this.setLayout(new BorderLayout());
        /*
         * 总体布局为边框式布局
         * 总体边框式布局north放置文本框
         */
        JTextField textField = new JTextField();
        textField.setPreferredSize(new Dimension(this.getWidth(), 50));
        this.add(textField, BorderLayout.NORTH);
        /*
         * 总体边框式布局center放置@panel(边框式布局）
         * @panel边框式布局north放置@panelN(网格布局)
         * @panel边框式布局center放置@panelC(卡片式布局)
         * @panelC卡片来切换@panel0(标准)和@panel1(科学)两种模式
         * @panel0,@panel1均为网格布局
         */
        JPanel panel = new JPanel();
        panel.setLayout(new BorderLayout());
        this.add(panel, BorderLayout.CENTER);

        JPanel panelN = new JPanel();
        panelN.setLayout(new GridLayout(1, 6));
        JButton MC = new JButton("MC");
        JButton MR = new JButton("MR");
        JButton M0 = new JButton("M+");
        JButton M1 = new JButton("M-");
        JButton MS = new JButton("MS");
        JButton M = new JButton("M");
        panelN.add(MC);
        panelN.add(MR);
        panelN.add(M0);
        panelN.add(M1);
        panelN.add(MS);
        panelN.add(M);
        panel.add(panelN, BorderLayout.NORTH);

        CardLayout cardLayout = new CardLayout();
        JPanel panelC = new JPanel();
        panelC.setLayout(cardLayout);

        JPanel panel0 = new JPanel();
        panel0.setLayout(new GridLayout(6, 4));
        JButton[] standredButton = new JButton[24];
        String str[] = {"%", "√", "x²", "1/x", "CE", "C", "×", "/",
                "7", "8", "9", "*", "4", "5", "6", "-",
                "1", "2", "3", "+", "±", "0", ".", "="};
        for (int i = 0; i < standredButton.length; i++) {
            standredButton[i] = new JButton(str[i]);
            String text = standredButton[i].getText();
            standredButton[i].addActionListener(new ActionListener() {
                @Override
                public void actionPerformed(ActionEvent e) {
                    // TODO Auto-generated method stub
                    if (text.equals("CE") || text.equals("C")) {
                        textField.setText("");
                    } else if (text.equals("=")) {
                        String expression = textField.getText();
                        Calculate cal = new Calculate();
                        textField.setText(cal.evaluateExpression(expression) + "");
                    } else if (text.equals("%")) { } else if (text.equals("√")) {
                        result = Double.parseDouble(textField.getText());
                        result = Math.sqrt(result);
                        textField.setText(result + "");
                    } else if (text.equals("x²")) {
                        result = Double.parseDouble(textField.getText());
                        result *= result;
                        textField.setText(result + "");
                    } else if (text.equals("1/x")) {
                        result = Double.parseDouble(textField.getText());
                        result = 1 / result;
                        textField.setText(result + "");
                    } else if (text.equals("±")) {
                        if (count == 0) {
                            textField.setText(textField.getText() + "-");
                            count = 1;
                        } else {
                            textField.setText(textField.getText() + "+");
                            count = 0;
                        }
                    } else if (text.equals("×")) {
                        textField.setText(textField.getText().substring(0, textField.getText().length() - 1));
                    } else {
                        textField.setText(textField.getText() + text);
                    }
                }
            }
            );
            panel0.add(standredButton[i]);
        }
        panelC.add(panel0);
        JPanel panel1 = new JPanel();
        panel1.setLayout(new GridLayout(7, 5));
        JButton scienceButton[] = new JButton[35];
        String str1[] = {
                "x²", "x^y", "sin", "cos", "tan",
                "√", "10^x", "log", "Exp", "Mod",
                "↑", "CE", "C", "×", "/",
                "π", "7", "8", "9", "*",
                "n!", "4", "5", "6", "-",
                "±", "1", "2", "3", "+",
                "(", ")", "0", ".", "="
        };
        for (int i = 0; i < str1.length; i++) {
            scienceButton[i] = new JButton(str1[i]);
            //scienceButton[i].addActionListener();
            panel1.add(scienceButton[i]);
        }
        panelC.add(panel1);
        panel.add(panelC, BorderLayout.CENTER);
        /*
         * 菜单
         */
        JMenuBar menuBar = new JMenuBar();
        this.setJMenuBar(menuBar);
        JMenu modelMenu = new JMenu("模式");
        menuBar.add(modelMenu);
        JMenuItem standred = new JMenuItem("标准");
        standred.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                // TODO Auto-generated method stub
                cardLayout.first(panelC);
            }
        });
        modelMenu.add(standred);
        JMenuItem science = new JMenuItem("科学");
        science.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                // TODO Auto-generated method stub
                cardLayout.last(panelC);
            }
        });
        modelMenu.add(science);
    }
}

class Calculate {
    /*使用空格分割字符串，以便后面使用分割函数使得将字符串分割成数组*/
    public String insetBlanks(String s) {
        String result = "";
        for (int i = 0; i < s.length(); i++) {
            if (s.charAt(i) == '(' || s.charAt(i) == ')' ||
                    s.charAt(i) == '+' || s.charAt(i) == '-'
                    || s.charAt(i) == '*' || s.charAt(i) == '/')
                result += " " + s.charAt(i) + " ";
            else
                result += s.charAt(i);
        }
        return result;
    }

    public double evaluateExpression(String expression) {
        Stack<Double> operandStack = new Stack<>();
        Stack<Character> operatorStack = new Stack<>();
        expression = insetBlanks(expression);
        String[] tokens = expression.split(" ");
        for (String token : tokens) {
            if (token.length() == 0)   /*如果是空格的话就继续循环，什么也不操作*/
                continue;
                /*如果是加减的话，因为加减的优先级最低，因此这里的只要遇到加减号，无论操作符栈中的是什么运算符都要运算*/
            else if (token.charAt(0) == '+' || token.charAt(0) == '-') {
                /*当栈不是空的，并且栈中最上面的一个元素是加减乘除的人任意一个*/
                while (!operatorStack.isEmpty() && (operatorStack.peek() == '-' || operatorStack.peek() == '+' || operatorStack.peek() == '/' || operatorStack.peek() == '*')) {
                    processAnOperator(operandStack, operatorStack);   //开始运算
                }
                operatorStack.push(token.charAt(0));   //运算完之后将当前的运算符入栈
            }
            /*当前运算符是乘除的时候，因为优先级高于加减，因此要判断最上面的是否是乘除，如果是乘除就运算，否则的话直接入栈*/
            else if (token.charAt(0) == '*' || token.charAt(0) == '/') {
                while (!operatorStack.isEmpty() && (operatorStack.peek() == '/' || operatorStack.peek() == '*')) {
                    processAnOperator(operandStack, operatorStack);
                }
                operatorStack.push(token.charAt(0));   //将当前操作符入栈
            }
            /*如果是左括号的话直接入栈，什么也不用操作,trim()函数是用来去除空格的，由于上面的分割操作可能会令操作符带有空格*/
            else if (token.trim().charAt(0) == '(') {
                operatorStack.push('(');
            }
            /*如果是右括号的话，清除栈中的运算符直至左括号*/
            else if (token.trim().charAt(0) == ')') {
                while (operatorStack.peek() != '(') {
                    processAnOperator(operandStack, operatorStack);    //开始运算
                }
                operatorStack.pop();   /*这里的是运算完之后清除左括号*/
            }
            /*这里如果是数字的话直接如数据的栈*/
            else {
                operandStack.push(Double.parseDouble(token));   /*将数字字符串转换成数字然后压入栈中*/
            }
        }
        /*最后当栈中不是空的时候继续运算，知道栈中为空即可*/
        while (!operatorStack.isEmpty()) {
            processAnOperator(operandStack, operatorStack);
        }
        return operandStack.pop();    /*此时数据栈中的数据就是运算的结果*/
    }

    /*处理栈中的两个数据，然后将栈中的两个数据运算之后将结果存储在栈中*/
    public void processAnOperator(Stack<Double> operandStack, Stack<Character> operatorStack) {
        char op = operatorStack.pop();  /*弹出一个操作符*/
        Double op1 = operandStack.pop();  /*从存储数据的栈中弹出连个两个数用来和操作符op运算*/
        Double op2 = operandStack.pop();
        if (op == '+')  /*如果操作符为+就执行加运算*/
            operandStack.push(op1 + op2);
        else if (op == '-')
            operandStack.push(op2 - op1);/*因为这个是栈的结构，自然是上面的数字是后面的，因此用op2-op1*/
        else if (op == '*')
            operandStack.push(op1 * op2);
        else if (op == '/')
            operandStack.push(op2 / op1);
    }
}

运行环境：IDEA

运行截图如图：

附：简单一点的请见https://blog.youkuaiyun.com/pointer_5/article/details/103073425