GUI简单布局-练习（监听事件）

简单计算器实现

需求

x + y = ？

填写两个数字，点击运算符切换当前运算符，点击等号，计算结果并填充到右侧；

实现思路

• 控件使用流式布局
• 用到按钮的事件监听器
• 不同按钮使用相同监听器，用setActionCommond进行区分

代码

package com.phil.gui1;

import com.sun.xml.internal.bind.v2.runtime.reflect.Accessor;

import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;



public class lessions2 {

    public static void main(String[] args) {
        //启动
        new Caculator();
    }

}

class Caculator extends Frame {
    public  Caculator() {

        this.setLayout(new FlowLayout());
        //输入框
        TextField textField1 = new TextField(10);
        textField1.setName("a");
        this.add(textField1);
        //计算符号按钮
        Button button = new Button();
        button.setName("o");
        this.add(button);
        //输入框
        TextField textField2 = new TextField(10);
        textField2.setName("b");
        this.add(textField2);
        //等于号按钮
        Button equal_button = new Button("=");
        equal_button.setName("e");
        this.add(equal_button);
        //结果框
        Label label = new Label("------");
        label.setBackground(Color.white);
        this.add(label);

        MyActionListener myActionListener = new MyActionListener(textField1, textField2, button, equal_button, label);

        setVisible(true);
        pack();
    }
}

class MyActionListener implements ActionListener {
    private TextField textField1, textField2;
    private Button button1, button2;
    private  Label label;
    private  String currentOP = "+";

    MyActionListener(TextField textField1, TextField textField2, Button button1, Button button2, Label label) {
        this.textField1 = textField1;
        this.textField2 = textField2;
        this.button1 = button1;
        button1.setLabel(currentOP);
        button1.setActionCommand("change");
        button1.addActionListener(this);
        this.button2 = button2;
        button2.setActionCommand("equal");
        button2.addActionListener(this);
        this.label = label;
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        String actionCommand = e.getActionCommand();
        if (actionCommand == "change") {
            if (currentOP=="+") {
                currentOP = "-";
            }else if (currentOP=="-") {
                currentOP = "*";
            }else if (currentOP=="*") {
                currentOP = "/";
            }else if (currentOP=="/") {
                currentOP = "+";
            }
            button1.setLabel(currentOP);
        }else if (actionCommand == "equal"){
            int value1 = Integer.parseInt(textField1.getText());
            int value2 = Integer.parseInt(textField2.getText());

            if (currentOP=="+") {
                label.setText("" + (value1 + value2));
            }else if (currentOP=="-") {
                label.setText("" + (value1 - value2));
            }else if (currentOP=="*") {
                label.setText("" + (value1 * value2));
            }else if (currentOP=="/") {
                if (value2!=0) {
                    label.setText("" + (value1 / value2));
                }else {
                    label.setText("err");
                }
            }
        }

    }

    public Label getLabel() {
        return label;
    }

    public void setLabel(Label label) {
        this.label = label;
    }
}

实现效果图

优化思路

把监听器作为MyFrame的内部类，可直接使用MyFrame的变量