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初学Java请帮小弟我看下这个程序为何

发布时间： 2013-10-17 17:26:17 作者： rapoo

初学Java，请帮我看下这个程序为何点击button没有响应？

import java.util.*;
import java.awt.Color;
import java.awt.event.*;
import javax.swing.*;
public class LoanJFrame extends JFrame implements ActionListener 
{
private JTextField text_money,text_rate,text_year;
private JSpinner spin_year,spin_month;
private JButton button;
private JTable table;

public LoanJFrame()
{
super("银行贷款按月还本付息的计算");
this.setBounds(300,240,800,400);
this.setBackground(Color.lightGray);
this.setDefaultCloseOperation(EXIT_ON_CLOSE);
JPanel panel=new JPanel();
this.getContentPane().add(panel,"North");
panel.add(new JLabel("贷款金额"));
text_money=new JTextField("100000",6);
panel.add(text_money);

panel.add(new JLabel("元　　贷款利率"));
text_rate=new JTextField("0.5025",6);
panel.add(text_rate);
panel.add(new JLabel("%/月　　贷款年限"));
text_year=new JTextField("5",3);
panel.add(text_year);

panel.add(new JLabel("年　　起始年月"));
Calendar today=Calendar.getInstance();
int year=today.get(Calendar.YEAR);
int nextmonth=today.get(Calendar.MONTH)+1;
nextmonth=nextmonth%12+1;
if(nextmonth==1)
year++;
spin_year=new JSpinner();
spin_year.setValue(year);
panel.add(spin_year);
panel.add(new JLabel("年"));
spin_month=new JSpinner(new SpinnerNumberModel(nextmonth,1,12,1));

panel.add(spin_month);
panel.add(new JLabel("月"));
button=new JButton("计算");
panel.add(button);
button.addActionListener(this);
//actionPerformed(null);
this.getContentPane().add(new JScrollPane(table));
this.setVisible(true);
}

public void actionPerformed(ActionEvent e)
{
String titles[]={"年月","本金金额（元）","月还本金（元）","月还利息（元","月还本息（元）"};
int months=Integer.parseInt(text_year.getText())*12;
Object datas[][]=new Object[months][5];
int year=Integer.parseInt(""+spin_year.getValue());
int mon=Integer.parseInt(""+spin_month.getValue());
double leavings=Double.parseDouble(""+text_money.getText());
double pay=leavings/months;
double rate=Double.parseDouble(""+text_rate.getText());
for(int i=0;i<months;i++)
{
datas[i][0]=year+"年"+mon+"月";
datas[i][1]=String.format("%9.2f",leavings);
datas[i][2]=String.format("%9.2f",pay);
datas[i][3]=String.format("%9.2f",leavings*rate*0.01);
datas[i][4]=String.format("%9.2f",pay+leavings*rate*0.01);
if(mon==12)
year++;
mon=mon%12+1;
leavings-=pay;
}
table=new JTable(datas,titles);
}

public static void main(String arg[])
{
new LoanJFrame();
}
}


我检查不出问题，难道我的Java系统库遭病毒破坏了？（是不是想太多？）
[解决办法]
是swing吧？

你在界面看下 button 的事件 是不是你后台的那个事件
[解决办法]
button.addActionListener(this);
[解决办法]
想太多了。你那个button要add到父容器中：

package com.withiter.csdn.test;

import java.util.*;
import java.awt.Color;
import java.awt.event.*;
import javax.swing.*;
public class LoanJFrame extends JFrame implements ActionListener 
{
    private JTextField text_money,text_rate,text_year;
    private JSpinner spin_year,spin_month;
    private JButton button;
    private JTable table;
     
    public LoanJFrame()
    {
        super("银行贷款按月还本付息的计算");
        this.setBounds(300,240,800,400);
        this.setBackground(Color.lightGray);
        this.setDefaultCloseOperation(EXIT_ON_CLOSE);
        JPanel panel=new JPanel();
        this.getContentPane().add(panel,"North");
        panel.add(new JLabel("贷款金额"));
        text_money=new JTextField("100000",6);
        panel.add(text_money);
         
        panel.add(new JLabel("元　　贷款利率"));
        text_rate=new JTextField("0.5025",6);
        panel.add(text_rate);
        panel.add(new JLabel("%/月　　贷款年限")); 
 
        text_year=new JTextField("5",3);
        panel.add(text_year);
         
        panel.add(new JLabel("年　　起始年月"));
        Calendar today=Calendar.getInstance();
        int year=today.get(Calendar.YEAR);
        int nextmonth=today.get(Calendar.MONTH)+1;
        nextmonth=nextmonth%12+1;
        if(nextmonth==1)
            year++;
        spin_year=new JSpinner();
        spin_year.setValue(year);
        panel.add(spin_year);
        panel.add(new JLabel("年"));
        spin_month=new JSpinner(new SpinnerNumberModel(nextmonth,1,12,1));
         
        panel.add(spin_month);
        panel.add(new JLabel("月"));
        button=new JButton("计算");
        panel.add(button);
        button.addActionListener(this);
//        actionPerformed(null);
        this.getContentPane().add(new JScrollPane(table));
        this.getContentPane().add(button);
        this.setVisible(true);
    }
     
    public void actionPerformed(ActionEvent e)
    {
    
    System.out.println("button clicked");
        String titles[]={"年月","本金金额（元）","月还本金（元）","月还利息（元","月还本息（元）"};
        int months=Integer.parseInt(text_year.getText())*12;
        Object datas[][]=new Object[months][5];
        int year=Integer.parseInt(""+spin_year.getValue());
        int mon=Integer.parseInt(""+spin_month.getValue());
        double leavings=Double.parseDouble(""+text_money.getText());
        double pay=leavings/months;
        double rate=Double.parseDouble(""+text_rate.getText());
        for(int i=0;i<months;i++)
        {
            datas[i][0]=year+"年"+mon+"月";
            datas[i][1]=String.format("%9.2f",leavings);
            datas[i][2]=String.format("%9.2f",pay);
            datas[i][3]=String.format("%9.2f",leavings*rate*0.01);
            datas[i][4]=String.format("%9.2f",pay+leavings*rate*0.01);
            if(mon==12)
                year++;
            mon=mon%12+1;
            leavings-=pay;
        }
        table=new JTable(datas,titles);
    }
     
    public static void main(String arg[])
    {
        new LoanJFrame();
    }
}


[解决办法]

import java.util.*;
import java.awt.Color;
import java.awt.event.*;
import javax.swing.*;

public class LoanJFrame extends JFrame implements ActionListener {
private JTextField text_money, text_rate, text_year;
private JSpinner spin_year, spin_month;
private JButton button;
private JTable table;
private JPanel panel = new JPanel();

public LoanJFrame() {
super("银行贷款按月还本付息的计算");
this.setBounds(300, 240, 800, 400);
this.setBackground(Color.lightGray);
this.setDefaultCloseOperation(EXIT_ON_CLOSE);

this.getContentPane().add(panel, "North");
panel.add(new JLabel("贷款金额"));
text_money = new JTextField("100000", 6);
panel.add(text_money);

panel.add(new JLabel("元　　贷款利率"));
text_rate = new JTextField("0.5025", 6); 
 
panel.add(text_rate);
panel.add(new JLabel("%/月　　贷款年限"));
text_year = new JTextField("5", 3);
panel.add(text_year);

panel.add(new JLabel("年　　起始年月"));
Calendar today = Calendar.getInstance();
int year = today.get(Calendar.YEAR);
int nextmonth = today.get(Calendar.MONTH) + 1;
nextmonth = nextmonth % 12 + 1;
if (nextmonth == 1)
year++;
spin_year = new JSpinner();
spin_year.setValue(year);
panel.add(spin_year);
panel.add(new JLabel("年"));
spin_month = new JSpinner(new SpinnerNumberModel(nextmonth, 1, 12, 1));

panel.add(spin_month);
panel.add(new JLabel("月"));
button = new JButton("计算");
panel.add(button);
button.addActionListener(this);
// actionPerformed(null);
this.getContentPane().add(new JScrollPane(table));
this.setVisible(true);
}

public void actionPerformed(ActionEvent e) {
String titles[] = { "年月", "本金金额（元）", "月还本金（元）", "月还利息（元", "月还本息（元）" };
int months = Integer.parseInt(text_year.getText()) * 12;
Object datas[][] = new Object[months][5];
int year = Integer.parseInt("" + spin_year.getValue());
int mon = Integer.parseInt("" + spin_month.getValue());
double leavings = Double.parseDouble("" + text_money.getText());
double pay = leavings / months;
double rate = Double.parseDouble("" + text_rate.getText());
for (int i = 0; i < months; i++) {
datas[i][0] = year + "年" + mon + "月";
datas[i][1] = String.format("%9.2f", leavings);
datas[i][2] = String.format("%9.2f", pay);
datas[i][3] = String.format("%9.2f", leavings * rate * 0.01);
datas[i][4] = String.format("%9.2f", pay + leavings * rate * 0.01);
if (mon == 12)
year++;
mon = mon % 12 + 1;
leavings -= pay;
}
table = new JTable(datas, titles);
panel.add(table);
panel.updateUI();
}

public static void main(String arg[]) {
new LoanJFrame();
}
}

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