手把手教你用Java的swing制作计算器

た入场券 2021-07-24 20:59 489阅读 0赞

> 其实学到Java这一块很多人会觉得很复杂实际上学会使用方法其实很简单

话不多说直接贴源码,如下：

package cn.sjy.calculator;
    
    import javax.swing.*;
    import java.awt.*;
    
    /**
     * 简易计算器
     * @author 石俊熠
     * 2020.7.13 11:24
     * 注：仿照某Java大佬的源码改之
     */
    public class Test {
        private String str=" ";//输入输出框显示内容
        private JTextField input;//输出框
        private JPanel button;//按钮区域
        private  String[] addbutton={"AC","求根","取反","/","7","8","9","*","4","5","6","-","1","2","3","+","+/-","0",".","="};
        private String showTextFiledNew;
    
        //设置主窗体
        public Test() {
            //初始化窗体
            JFrame f = new JFrame("计算器");
            Container c = f.getContentPane();
            c.setLayout(new BoxLayout(f.getContentPane(), BoxLayout.Y_AXIS));//设置排列布局为Y轴排列
    
            f.setLocation(200, 300);
            //f.setSize(500, 600);
            f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
            f.setVisible(true);
    
            input = new JTextField(30);//设置输入框的长度为30
            input.setHorizontalAlignment(JTextField.RIGHT);//设置输入框内容的对齐方式，设置为右对齐
            JPanel jPanel = new JPanel();//建立一个面板
            jPanel.add(input);
            c.add(jPanel);
    
            GridBagLayout gridBagLayout = new GridBagLayout();
            GridBagConstraints cs = new GridBagConstraints();
            button = new JPanel();
            button.setLayout(gridBagLayout);
            for (int i = 0; i < addbutton.length; i++) {
                if ((i + 1) % 4 == 0) {
                    cs.gridwidth = GridBagConstraints.REMAINDER;
                } else {
                    cs.fill = GridBagConstraints.BOTH;//使组件完全填充其显示区域
                    cs.weightx = 1.0;
                    cs.gridwidth = 1;
                }
                JButton b = new JButton(addbutton[i]);
                gridBagLayout.setConstraints(b, cs);//设置组件的约束
                b.addActionListener(e -> {
                    String command = e.getActionCommand();
                    setShowTextFiledNew(command);
                });
                button.add(b);
            }
            c.add(button);
            f.pack();
        }
    
        /**
         * 设置显示内容得窗体
         * @param command 按钮点击命令
         * 如果按下=执行计算命令
         * 如果按下运算符 则格式为 空格+运算符+空格
         * 如果按下数字 则直接拼接
         * 需要更多资料可以加群：756584822
         */
        public void setShowTextFiledNew(String command) {
            if(command.equals("=")){
                str = getResult(str);
            }else if(command.equals("+")||command.equals("-")||command.equals("*")||command.equals("/")||command.equals("求根")||command.equals("取反")){
                str = str+" "+command+" ";
            }else if(command.equals("AC")){
                str = "";
            }else{
                str = str+command;
            }
            input.setText(str);//将按钮的信息返回到input中
        }
    
        /**
         * 计算模块
         * @param str 需要计算的字符串
         * 根据空格进行分割成字符串数组
         * 然后判断是哪种类型进行计算
         *通过一个result来存放那个结果
         */
        private String getResult(String str) {
            Double result = 0.0;//用来存放结果
            String[] need = str.split(" ");//进行字符串分割
            for (String j : need) {
                System.out.print(j+" ");
            }
            for (int i = 0; i < need.length; i++) {
                switch (need[i]){
                    case "+":
                        if (result == 0.0 && i==1){
                            result=result+(Double.parseDouble(need[i-1])+Double.parseDouble(need[i+1]));
                            break;
                        }else{
                            result=result+Double.parseDouble(need[i+1]);
                            break;
                        }
                    case "-":
                            if(Double.parseDouble(need[i-1])>=Double.parseDouble(need[i+1])){
                                result = (Double.parseDouble(need[i-1])-Double.parseDouble(need[i+1]));
                                break;
                            }else {
                                result = +(Double.parseDouble(need[i-1])-Double.parseDouble(need[i+1]));
                                break;
                            }
                    case "*":
                        result=result+(Double.parseDouble(need[i-1])*Double.parseDouble(need[i+1]));
                        break;
                    case "/":
                        result=result+(Double.parseDouble(need[i-1])/Double.parseDouble(need[i+1]));
                        break;
                    case "求根":
                        result=result+(Math.sqrt(Double.parseDouble(need[i-1])));
                        break;
                    case "取反":
                        result=result+(-Double.parseDouble(need[i-1]));
                        break;
                }
            }
            return  result+"";
        }
    
        //设置主方法，调用Test方法
        public static void main(String[] args ){
            new Test();
        }
    }
    
    效果如下

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