手把手教你用Java的swing製作計算器

其實學到Java這一塊很多人會覺得很複雜實際上學會使用方法其實很簡單

話不多說直接貼源碼,如下：

package cn.sjy.calculator;

import javax.swing.*;
import java.awt.*;

/**
 * 簡易計算器
 * @author 石俊熠
 * 2020.7.13 11:24
 * 注：仿照某Java大佬的源碼改之
 */
public class Test {
    private String str=" ";//輸入輸出框顯示內容
    private JTextField input;//輸出框
    private JPanel button;//按鈕區域
    private  String[] addbutton={"AC","求根","取反","/","7","8","9","*","4","5","6","-","1","2","3","+","+/-","0",".","="};
    private String showTextFiledNew;

    //設置主窗體
    public Test() {
        //初始化窗體
        JFrame f = new JFrame("計算器");
        Container c = f.getContentPane();
        c.setLayout(new BoxLayout(f.getContentPane(), BoxLayout.Y_AXIS));//設置排列布局爲Y軸排列

        f.setLocation(200, 300);
        //f.setSize(500, 600);
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.setVisible(true);

        input = new JTextField(30);//設置輸入框的長度爲30
        input.setHorizontalAlignment(JTextField.RIGHT);//設置輸入框內容的對齊方式，設置爲右對齊
        JPanel jPanel = new JPanel();//建立一個面板
        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;//使組件完全填充其顯示區域
                cs.weightx = 1.0;
                cs.gridwidth = 1;
            }
            JButton b = new JButton(addbutton[i]);
            gridBagLayout.setConstraints(b, cs);//設置組件的約束
            b.addActionListener(e -> {
                String command = e.getActionCommand();
                setShowTextFiledNew(command);
            });
            button.add(b);
        }
        c.add(button);
        f.pack();
    }

    /**
     * 設置顯示內容得窗體
     * @param command 按鈕點擊命令
     * 如果按下=執行計算命令
     * 如果按下運算符 則格式爲 空格+運算符+空格
     * 如果按下數字 則直接拼接
     * 需要更多資料可以加羣：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);//將按鈕的信息返回到input中
    }

    /**
     * 計算模塊
     * @param str 需要計算的字符串
     * 根據空格進行分割成字符串數組
     * 然後判斷是哪種類型進行計算
     *通過一個result來存放那個結果
     */
    private String getResult(String str) {
        Double result = 0.0;//用來存放結果
        String[] need = str.split(" ");//進行字符串分割
        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+"";
    }

    //設置主方法，調用Test方法
    public static void main(String[] args ){
        new Test();
    }
}

效果如下