在 Frame中显示两个输入框，然后做除法，最后显示结果。 如果除数为0，要进行异常情况的处理

import java.text.DecimalFormat;
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
//*********Found******** 
public class Java_3 extends ________ implements ActionListener {
    private JTextField input1, input2, output;
    private int number1, number2;
    private double result;
    // 初始化 
    public Java_3() {
        //*********Found******** 
        ______("示范异常");
        Container c = getContentPane();
        c.setLayout(new GridLayout(3, 2));
        c.add(new JLabel("输入分子",
                SwingConstants.RIGHT));
        input1 = new JTextField(10);
        c.add(input1);
        c.add(new JLabel("输入分母和回车",
                SwingConstants.RIGHT));
        input2 = new JTextField(10);
        c.add(input2);
        input2.addActionListener(this);
        c.add(new JLabel("计算结果", SwingConstants.RIGHT));
        output = new JTextField();
        c.add(output);
        setSize(425, 100);
        show();
    }
    //处理 GUI 事件 
    public void actionPerformed(ActionEvent e) {
        DecimalFormat precision3 = new DecimalFormat("0.000");
        output.setText(""); // 空的JTextField输出 
        //*********Found******** 
        ___________ {
            number1 = Integer.parseInt(input1.getText());
            number2 = Integer.parseInt(input2.getText());
            result = quotient(number1, number2);
            //*********Found******** 
            output.setText(_______________________________);
        } 
        catch (NumberFormatException nfe) {
            JOptionPane.showMessageDialog(this,
                    "你必须输入两个整数",
                    "非法数字格式",
                    JOptionPane.ERROR_MESSAGE);
        } 
        catch (Exception dbze) {
            //*********Found******** 
            _______________________________(this,
                    "除法异常",
                    "除数为零",
                    JOptionPane.ERROR_MESSAGE);
        }
    }
// 定义求商的方法，如遇除数为零时，能抛出异常。 
    public double quotient(int numerator, int denominator)
            throws Exception {
        if (denominator == 0) {
            throw new Exception();
        }
        return (double) numerator / denominator;
    }
 
    public static void main(String args[]) {
        Java_3 app = new Java_3();
        app.addWindowListener(
                new WindowAdapter() {
                    public void windowClosing(WindowEvent e) {
                        e.getWindow().dispose();
                        System.exit(0);
                    }
                });
    }
}
/* JOptionPane类的常用静态方法如下： 
showInputDialog() 
showConfirmDialog() 
showMessageDialog() 
showOptionDialog() 
 */