10.28

public class CatchWho 
{ 
    public static void main(String[] args) 
    { 
        try 
    { 
                try 
        { 
                    throw new ArrayIndexOutOfBoundsException(); 
                } 
                catch(ArrayIndexOutOfBoundsException e) 
        { 
                       System.out.println(  "ArrayIndexOutOfBoundsException" +  "/内层try-catch"); 
                }
 
            throw new ArithmeticException(); 
        } 
        catch(ArithmeticException e) 
    { 
            System.out.println("发生ArithmeticException"); 
        } 
        catch(ArrayIndexOutOfBoundsException e) 
    { 
           System.out.println(  "ArrayIndexOutOfBoundsException" + "/外层try-catch"); 
        } 
    } 
}

代码运行结果如下：

ArrayIndexOutOfBoundsException/内层try-catch
发生ArithmeticException

public class CatchWho2 
{ 
    public static void main(String[] args) 
    { 
        try 
    {
                try 
        { 
                    throw new ArrayIndexOutOfBoundsException(); 
                } 
                catch(ArithmeticException e) 
        { 
                    System.out.println( "ArrayIndexOutOfBoundsException" + "/内层try-catch"); 
                }
            throw new ArithmeticException(); 
        } 
        catch(ArithmeticException e) {
     
            System.out.println("发生ArithmeticException"); 
        } 
        catch(ArrayIndexOutOfBoundsException e) 
    { 
            System.out.println( "ArrayIndexOutOfBoundsException" + "/外层try-catch"); 
        } 
    } 
}

运行结果如下：

ArrayIndexOutOfBoundsException/外层try-catch

import java.io.*; 
 
public class CheckedExceptionDemo 
{ 
    public static void main(String[] args)  
    { 
        try 
    { 
            BufferedReader buf = new BufferedReader( 
                new InputStreamReader(System.in));    //抛出受控的异常
            System.out.print("请输入整数: "); 
            int input = Integer.parseInt(buf.readLine()); //有可能引发运行时异常
            System.out.println("input x 10 = " + (input*10)); 
          } 
        //以下异常处理语句块是必须的，否则无法通过编译
        catch(IOException e) 
    { 
            System.out.println("I/O错误"); 
        } 
        //以下异常处理语句块可以省略，不影响编译，但在运行时出错
        catch(NumberFormatException e) 
    { 
            System.out.println("输入必须为整数"); 
        }
    } 
}

运行结果如下：

请输入整数: 15
input x 10 = 150

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");
        
        }
    
    }

}

运行结果如下：

in Level 1
in Level 2
in Level 3
Level 3:class java.lang.ArithmeticException
In Level 3 finally
In Level 2 finally
In Level 1 finally

/**
 * 自定义的异常类
 * @author JinXuLiang
 *
 */
class MyException extends Exception
{
    public MyException(String Message) 
   {
        super(Message);
    }
    public MyException(String message, Throwable cause) 
    {
        super(message, cause);
    }
     public MyException( Throwable cause) 
    {
        super(cause);
    }

}

public class ExceptionLinkInRealWorld 
{
   public static void main( String args[] )
   {
      try 
      {
         throwExceptionMethod();  //有可能抛出异常的方法调用
      }
      catch ( MyException e )
      {
         System.err.println( e.getMessage() );
         System.err.println(e.getCause().getMessage());
      }
      catch ( Exception e )
      {
         System.err.println( "Exception handled in main" );
      }
      doesNotThrowException(); //不抛出异常的方法调用
   }

   public static void throwExceptionMethod() throws MyException
   {
      
      try 
      {
         System.out.println( "Method throwException" );

         throw new Exception("系统运行时引发的特定的异常");  // 产生了一个特定的异常
      }
      catch( Exception e )
      {
         System.err.println(
            "Exception handled in method throwException" );
         //转换为一个自定义异常，再抛出
         throw new MyException("在方法执行时出现异常",e);
         
      }
      finally 
      {
         System.err.println(
            "Finally executed in throwException" );
      }

      // any code here would not be reached
   }

   public static void doesNotThrowException()
   {
      try 
      {
         System.out.println( "Method doesNotThrowException" );
      }
      catch( Exception e )
      {
         System.err.println( e.toString() );
      }
      finally 
      {
         System.err.println(
            "Finally executed in doesNotThrowException" );
      }

      System.out.println(
         "End of method doesNotThrowException" );
   }
}

运行结果如下：

Method throwException
Exception handled in method throwException
Finally executed in throwException
在方法执行时出现异常
系统运行时引发的特定的异常
Finally executed in doesNotThrowException
Method doesNotThrowException
End of method doesNotThrowException

public class ExplorationJDKSource 
{

    /**
     * @param args
     */
    public static void main(String[] args) 
    {
        System.out.println(new A());
    }

}

class A{}

运行结果如下：

A@6d9c638

import java.io.*;


public class OverrideThrows
{
    public void test()throws IOException
    {
        FileInputStream fis = new FileInputStream("a.txt");
    }
}
class Sub extends OverrideThrows
{
    //如果test方法声明抛出了比父类方法更大的异常,比如Exception
    //则代码将无法编译……
    public void test() throws FileNotFoundException
    {
            //...
    }
}

运行结果如下：

A@6d9c638

// UsingExceptions.java
// Demonstrating the getMessage and printStackTrace
// methods inherited into all exception classes.
public class PrintExceptionStack 
{
   public static void main( String args[] )
   {
      try 
      {
         method1();
      }
      catch ( Exception e ) 
      {
         System.err.println( e.getMessage() + "
" );
         e.printStackTrace();
      }
   }

   public static void method1() throws Exception
   {
      method2();
   }

   public static void method2() throws Exception
   {
      method3();
   }

   public static void method3() throws Exception
   {
      throw new Exception( "Exception thrown in method3" );
   }
}

运行结果如下：

Exception thrown in method3

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");
        
        }
    
    }


}

运行结果如下：

in main
Exception is thrown in main

public class ThrowDemo 
{ 
    public static void main(String[] args) 
{ 
//        try 
//      {
            double data = 100 / 0.0;
            System.out.println("浮点数除以零：" + data); 
//            if(String.valueOf(data).equals("Infinity"))
//            { 
//                System.out.println("In Here" ); 
//                throw new ArithmeticException("除零异常");
//            }
//        } 
//        catch(ArithmeticException e) 
//      { 
//            System.out.println(e); 
//        } 
    } 
}
 

运行结果如下：

浮点数除以零：Infinity

import java.io.*;
public class ThrowMultiExceptionsDemo 
{ 
    public static void main(String[] args) 
    { 
      try 
      { 
            throwsTest(); 
       } 
        catch(IOException e) 
    { 
            System.out.println("捕捉异常"); 
        }
    }

    private static void throwsTest()  throws ArithmeticException,IOException 
    { 
        System.out.println("这只是一个测试"); 
        // 程序处理过程假设发生异常
        throw new IOException(); 
        //throw new ArithmeticException(); 
    } 
}

运行结果如下：

这只是一个测试
捕捉异常