动手动脑五

1.AboutException.java

源代码：

package 动手动脑;
import javax.swing.*;
publicclass AboutException {
    publicstaticvoid main(String[] args) 
       {
    inti=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 (einstanceof ArithmeticException)
                System.out.println("被0除");
            else
            {  
                System.out.println(e.getMessage());
                
            }
        }

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

运行截图：

Try中监测“k=i/j;”这一语句，当j等于0时给出错误。

2

这是因为两段程序在编译之后生成的是不同的字节码指令，JVM在具体实现这两个指令时采用的是不同的方法，所以会出现不同的结果。

3.CatchWho.java

package 动手动脑;

publicclass CatchWho {
    publicstaticvoid main(String[] args) { 
try { 
    try { 
    thrownew ArrayIndexOutOfBoundsException(); 
    } 
    catch(ArrayIndexOutOfBoundsException e) { 
        System.out.println(  "ArrayIndexOutOfBoundsException" +  "/内层try-catch"); 
    }

thrownew ArithmeticException(); 
        } 
catch(ArithmeticException e) { 
            System.out.println("发生ArithmeticException"); 
        } 
catch(ArrayIndexOutOfBoundsException e) { 
           System.out.println(  "ArrayIndexOutOfBoundsException" + "/外层try-catch"); 
        } 
    } 
}

4CatchWho2.java

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"); 
        } 
    } 
}

5  EmbededFinally.Java

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");

        }

    }

}

6SystemExitAndFinally.java

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");

        }

    }


}

7PrintExceptionStack.java

// 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() + "\n" );
         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" );
   }
}