每日日报之“动手动脑”作业五

 

 

 代码如下:

import javax.swing.*;

class AboutException {
   public static void main(String[] a) 
   {
      int i=1, j=0, k;
      k=i/j;


    try
    {
        
        k = i/j;    // Causes division-by-zero exception
        //throw new Exception("Hello.Exception!");
    }
    
    catch ( ArithmeticException e)
    {
        System.out.println("被0除.  "+ e.getMessage());
    }
    
    catch (Exception e)
    {
        if (e instanceof ArithmeticException)
            System.out.println("被0除");
        else
        {  
            System.out.println(e.getMessage());
            
        }
    }

    
    finally
         {
             JOptionPane.showConfirmDialog(null,"OK");
         }
        
  }
}

catch语句用于处理try语句中可能会发生错误的代码所发生的异常。不管是否有异常发生,finally语句都会被执行。如果没有提供合适的异常处理代码,JVM将会结束掉整个应用程序。

 

 

 

 

 

 

 运行结果:

 

 

 

 

代码如下:

 

 

 

 

 

 运行结果:

 

 

 

代码如下:

 

 

 

public class EmbededFinally 
{

    
    public static void main(String args[]) 
    {
        
        int result;
        
        try 
        {
            
            System.out.println("in Level 1");

           
             try 
            {
                
                System.out.println("in Level 2");
  result=100/0;  //Level 2
               
                 try 
                {
                   
                     System.out.println("in Level 3");
                      
                     result=100/0;  //Level 3
                
                } 
                
                catch (Exception e) 
                {
                    
                    System.out.println("Level 3:" + e.getClass().toString());
                
                }
                
                
                finally 
                {
                    
                    System.out.println("In Level 3 finally");
                
                }
                
               
                // result=100/0;  //Level 2

            
                }
            
            catch (Exception e) 
            {
               
                 System.out.println("Level 2:" + e.getClass().toString());
           
             }
             finally 
            {
                
                System.out.println("In Level 2 finally");
           
             }
             
            // result = 100 / 0;  //level 1
        
        } 
        
        catch (Exception e) 
        {
            
            System.out.println("Level 1:" + e.getClass().toString());
        
        }
        
        finally 
        {
           
.             System.out.println("In Level 1 finally");
        
        }
    
    }

}

catch语句只接受相邻的try语句抛出的错误。无论有无异常finally语句都会执行。

 

 

 

代码如下: 

public class SystemExitAndFinally 
{

    
    public static void main(String[] args)
    
    {
        
        try
        {

            
            System.out.println("in main");
            
            throw new Exception("Exception is thrown in main");

                    //System.exit(0);

        
        }
        
        catch(Exception e)

            {
            
            System.out.println(e.getMessage());
            
            System.exit(0);
        
        }
        
        finally
        
        {
            
            System.out.println("in finally");
        
        }
    
    }


}

System.exit(0)是强制退出程序,System.exit(1)是异常终止。一般情况下,无论有无异常finally语句都会执行,但此代码catch语句中有System.exit(0)强制退出程序,故不会执行finally语句。

 

posted @ 2020-10-28 21:38  谦寻  阅读(58)  评论(0编辑  收藏  举报