java gui求1-n的和

Question

编写GUI程序，用户在图形界面输入任意n，计算得出1+2+…+n的值

Answer 1

我给你写下

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.*;
public class SumFrame extends JFrame implements ActionListener {
    private static final long serialVersionUID = -3059616600875760053L;
    JLabel lable, labTotal;
    JTextField textLable, textTotal;
    static JButton butSummation;
    public SumFrame() {
        lable = new JLabel("輸入n");
        labTotal = new JLabel("前n项和");
        textLable = new JTextField("", 10);
        textTotal = new JTextField("", 10);
        butSummation = new JButton("计算");
        lable.setBounds(30, 30, 120, 30);
        textLable.setBounds(180, 30, 120, 30);
        labTotal.setBounds(30, 130, 120, 30);
        textTotal.setBounds(180, 130, 120, 30);
        butSummation.setBounds(160, 180, 120, 30);
        add(lable);
        add(textLable);
        add(labTotal);
        add(textTotal);
        add(butSummation);
        setLayout(null);
        setBounds(200, 100, 400, 300);
        // 窗口在屏幕中间显示
        setLocationRelativeTo(null);
        setTitle("求总量");
        setResizable(false);
        setVisible(true);
    }
    public static void main(String[] args) {
        SumFrame summationForm = new SumFrame();
        butSummation.addActionListener(summationForm);
        summationForm.add(butSummation);
    }
    public void actionPerformed(ActionEvent e) {
        JButton jb = (JButton) e.getSource();
        if (jb == butSummation) {
            String Mathematics = textLable.getText();
            try {
                int a = Integer.parseInt(Mathematics);
                int sum=0;
                for(int i=1;i<=a;i++){
                    sum+=i;
                }
                textTotal.setText(String.valueOf(sum));
            } catch (Exception e2) {
                JOptionPane.showMessageDialog(this, "输入的格式错误！", "提示对话框", JOptionPane.DEFAULT_OPTION);
            }
        }
    }
}