moreexceptiondemo.java

学习参考,java基本语法练习,包括一些常用的技巧

//该实例演示了JAVA异常处理方法
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;

public class MoreExceptionDemo extends JApplet
{
 	//声明变量
 	private JTextField txtNumerator, txtDenominator, txtResult;
	private String strTip = "输入整数并按'=' 进行除法运算";
	private JLabel lblTip = new JLabel(strTip, JLabel.CENTER);
	private String strWelcome = "欢迎使用整数除法运算器";
	private JLabel lblStatus = new JLabel(strWelcome, JLabel.CENTER);
	
	public void init( ) 
	{
		//组件初始化
		Font f = new Font("宋体", Font.PLAIN, 12);
		lblTip.setFont(f);
		lblTip.setForeground(Color.blue);
		lblStatus.setFont(f);
		lblStatus.setForeground(Color.blue);
		txtNumerator = new JTextField("0", 7);
		txtNumerator.setFont(f);
		txtDenominator = new JTextField("1", 7);
		txtDenominator.setFont(f);
		txtResult = new JTextField("0", 7);
		txtResult.setFont(f);
		JLabel lblDivSign = new JLabel("/", JLabel.CENTER);
		lblDivSign.setFont(new Font ("宋体", Font.PLAIN, 12));
		lblDivSign.setForeground(Color.black);
		JButton btnEqual = new JButton("=");
		btnEqual.setFont(f);
		//使用匿名内部类注册事件监听器
		btnEqual.addActionListener(new ActionListener() 
		{
			public void actionPerformed(ActionEvent evt) 
			{
			//进行异常处理
   			try 
   			{	
   				//执行除法
   				performDivision();
   			} 
   			//捕获数据格式异常
   			catch (NumberFormatException e) 
   			{
   				lblStatus.setForeground(Color.red);
				lblStatus.setText("被除数和除数必须为整数,请重试!");
				lblTip.setText(" ");
   			}
   			//捕获算术运算异常
   			catch (ArithmeticException e) 
   			{
   				lblStatus.setForeground(Color.red);
				lblStatus.setText("不能被0除,请重试!");
				lblTip.setText(" ");
   			}
			}
		});
		
		JPanel p1 = new JPanel();
		p1.add(txtNumerator); 
        p1.add(lblDivSign);
        p1.add(txtDenominator);
  	    p1.add(btnEqual);
  	    p1.add(txtResult);
		JPanel p2 = new JPanel();
		p2.add(lblTip);
		JPanel p3 = new JPanel();
		p3.add(lblStatus);
		getContentPane().add(p1, "Center");  
		getContentPane().add(p2, "South"); 
		getContentPane().add(p3, "North");  
	}
	//执行除法运算方法
	public void performDivision () throws NumberFormatException, ArithmeticException 
	{
    	int intNum = Integer.parseInt(txtNumerator.getText());
        int intDenom = Integer.parseInt(txtDenominator.getText());
        int intDiv = intNum/intDenom;
        txtResult.setText(""+intDiv);
        lblStatus.setForeground(Color.blue);
        lblStatus.setText("正确执行除数运算!");
        lblTip.setText(strTip);  
     }
}