try{} and catch{}

import java.util.* ;

public class SquareFix 
{

  public static void main ( String[] a )
  {
    Scanner scan = new Scanner( System.in  );
    int num ;

    System.out.print("Enter an integer: ");

    try
    { 
      num = scan.nextInt();      
      System.out.println("The square of " + num + " is " + num*num );
    } 

    catch ( InputMismatchException ex )
    { 
      System.out.println("You entered bad data." );
      System.out.println("Run the program again." );
    } 

    System.out.println("Good-by" );

  }
}

To catch an Exception:

1. Put code that might throw an Exception inside a try block.
2. Put code that handles the Exception inside a catch block.
3. The catch block must immediately follow the try block.

If a statement inside the try block throws a InputMismatchException, the catch block immediately starts running. The remaining statements in the try block are skipped.

The catch block parameter ex refers to the Exception object that is thrown. However, this example does nothing with it.

After the catch block is executed, execution continues with the statement that follows the catch block. Execution does not return to the try block.