JAVA polymorphism and exception handling jobs--hands-on brain and experimental problems after class

1, read the following code (Catchwho.java), write out the program running results:

1) Source Code

Public class Catchwho

{

Public Static void Main (string[] args)

{

Try

{

Try

{

Throw New ArrayIndexOutOfBoundsException ();

}

Catch (ArrayIndexOutOfBoundsException e)

{

System. out. println ("arrayindexoutofboundsexception" + "/Inner layer Try-catch");

}

Throw New ArithmeticException ();

}

Catch (ArithmeticException e)

{

System. out. println ("occurs ArithmeticException");

}

Catch (ArrayIndexOutOfBoundsException e)

{

System. out. println ("arrayindexoutofboundsexception" + "/outer try-catch");

}

}

}

2) Running results

1, write out the results of Catchwho2.java program operation

1, 1) source code

Public class CatchWho2

{

Public Static void Main (string[] args)

{

Try

{

Try

{

Throw New ArrayIndexOutOfBoundsException ();

}

Catch (ArithmeticException e)

{

System. out. println ("arrayindexoutofboundsexception" + "/Inner layer Try-catch");

}

Throw New ArithmeticException ();

}

Catch (ArithmeticException e)

{

System. out. println ("occurs ArithmeticException");

}

Catch (ArrayIndexOutOfBoundsException e)

{

System. out. println ("arrayindexoutofboundsexception" + "/outer try-catch");

}

}

}

1) Running results

3. Please read the Embedfinally.java example before running it, observe its output and summarize it.

1) Source Code

Public class Embededfinally

{

Public Static void Main (String args[])

{

int result;

Try

{

System. out. println ("at level 1");

Try

{

System.  out. println ("at Level 2");//result=100/0; Level 2

Try

{

System. out. println ("at Level 3");

result=100/0; Level 3

}

Catch (Exception e)

{

System. out. println ("Level 3:" + E.getclass (). toString ());

}

finally

{

System. out. println ("at level 3 finally");

}

result=100/0; Level 2

}

Catch (Exception e)

{

System. out. println ("Level 2:" + E.getclass (). toString ());

}

finally

{

System. out. println ("at level 2 finally");

}

result = 100/0; Level 1

}

Catch (Exception e)

{

System. out. println ("Level 1:" + e.getclass (). toString ());

}

finally

{

System. out. println ("at level 1 finally");

}

}

}

2) Running results

1) Summary

Executes a try statement, has catch execution, and finally executes a finally statement.

4, discrimination: Finally statement block will be executed? Please answer these questions through the Systemexitandfinally.java sample program

1) Source Code

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");

}

}

}

2) Running results

3) Summary

The finally statement is not necessarily executed, and in the Catch statement, an exit (0) statement exits. To see the specifics, the catch statement is handled.

5, write a program, this program at run time requires the user input an integer, representing a course of the exam results, the program then give "failed", "Pass", "Medium", "good", "excellent" conclusion. Requires that the program be robust enough that it does not crash regardless of what the user enters.

1) Source Code

import java.io.*;

Public class Grade {

Public Static void Main (string[] args) {

TODO auto-generated Method stub

String a = null;

int g;

BufferedReader Strin =new bufferedreader (new InputStreamReader (System. in));

Try

{

System. out. println ("Please enter a score (integer):");

A = Strin.readline ();

}

Catch (Exception e)

{

System. out. println (E.getmessage ());

}

Try

{

g = Integer. parseint (a);

if (g<=100&&g>=90)

System. out. println ("excellent");

Else if (g>=80&&g<90)

System. out. println ("good");

Else if (g>=70&&g<80)

System. out. println ("medium");

Else if (g>=60&&g<70)

System. out. println ("Pass");

Else if (g<60)

System. out. println ("failing");

Else

System. out. println ("score error");

}

Catch (NumberFormatException e)

{

System. out. println ("input error");

}

}

}

2) Running results

JAVA polymorphism and exception handling jobs--hands-on brain and experimental problems after class