Question

用java.swing，使得按下按钮可以使前两个文本框中的数字相加显示在第三个文本框总

Answer 1

package test;

import java.awt.Color;
import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;

public class Sum extends JFrame implements ActionListener{
JPanel panel;
JLabel oneLabel;
JLabel twoLabel;
JButton sumButton;
JTextField oneTextField;
JTextField twoTextField;
JTextField threeTextField;

public Sum() {
super("求和");
panel = new JPanel();
panel.setBackground(new Color(192, 192, 192));
panel.setLayout(new FlowLayout());
this.add(panel);
oneLabel = new JLabel("输入第一个数");
twoLabel = new JLabel("输入第二个数");
oneTextField = new JTextField(15);
twoTextField = new JTextField(15);
threeTextField = new JTextField(15);
sumButton = new JButton("求和");
oneTextField.addActionListener(this);
twoTextField.addActionListener(this);
sumButton.addActionListener(this);
panel.add(oneLabel);
panel.add(oneTextField);
panel.add(twoLabel);
panel.add(twoTextField);
panel.add(sumButton);
panel.add(threeTextField);
this.setBounds(200, 100, 200, 240);
this.setResizable(true);
this.setVisible(true);
}
public static void main(String[] args) {
new Sum();

}
@Override
public void actionPerformed(ActionEvent e) {

String one = oneTextField.getText().trim();
String two = twoTextField.getText().trim();
int sum = Integer.parseInt(one)+Integer.parseInt(two);
threeTextField.setText(String.valueOf(sum));
}

}
还需要 自己 添加一些 判断 验证 数据的 合法性等

Answer 2

按键.addActionListener(new ActionListener() {

@Override
public void actionPerformed(ActionEvent event) {
String s = Double.parseDouble(文本框1.getText()) + Double.parseDouble(文本框2.getText()) + "";
文本框3.setText(s);

}
});