try() - catch() Block

There are 5 keyword used in Exception such as:-
1)    try
2)   catch
3)   finally
4)   throw
5)   throws

1)  try Block: 

Its used to place code that may throw exception. It must be used with catch or finally block.
syntax are given below.

A)   syntax:-  try and catch block:-

         try{

                   // code that may be exceptions occurs

             }

         catch(Exception_class name ref )

            {

                  //code

            }

B)  syntax:- try and finally

          try{

                 //code where may be exception occurs

             }

          finally(){}

Example:1  write a simple program without exception handling.

     public class A{   

       public static void main(String args[]){   

        int a=10/0;//may throw exception   

             System.out.println("some other code...");   

       }  }

output:- 

 Exception in thread "main" java.lang.ArithmeticException: / by zero
          at A.main(A.java:8)

 In example 1 occur exception and "some other code" statement of  the program are not printed here.

so lets write a program to solve the problem.

Example:- program to handle exception .

public class ExceptionExample {
public static void main(String[] args) {
    try{
        int a=10/0;
        }
    catch(Exception e)
    {
        System.out.println(e);}

System.out.println("some other code");
}}

output: 

java.lang.ArithmeticException: / by zero

some other code

Now in this program we used to try{}block and catch(){}block so printed the "some other code' statement in the program.

2)  catch block:- 

 It is used to handle exception. It must be used with try block.

  Syntax:-   

      try
           {    
                  //code where may be exception occure
            }
      catch(Exception_class_ref)
           {
                  //code
           }

Example:- 

import java.util.concurrent.ExecutionException;
public class ExceptionCatchBlock {
public static void main(String[] args) {
    try{
        String s1=null;
        System.out.println(s1.length());

        }

   catch(Exception e){System.out.println(e);}
    System.out.println("other code");
 }
 }

output:- 

java.lang.NullPointerException

other code

Example:- Write a program to use catch block with array. 

public class a2 {
public static void main(String[] args) {
    try{
        int[] a=new int[5];
         a[5]=20;
      System.out.println(a[5]);}
     catch(Exception  e){System.out.println(e);
           System.out.println("some other code");
    }}}

 

output:- 

java.lang.ArrayIndexOutOfBoundsException: 5

some other code

I will describe finally throw and throws  further.

What is Exception handling?

Exception Handling

Questions:-

What is exception handling?

Answer:-

In java,exception is an object or event which is thrown at run-time and it is mechanism to handled run time-error.

what is different between in Error and Exception:-

there are some type of error such as:-

1) Syntax error.

2) Logical error.

3) Run-time error.

Syntax Error-

Syntax error is an error in the syntax a sequence of character.it is cause by a programmer because writing mistake of the programmed. for example:-

1) int a=10;   // it is correct.

2) int 20=b;    // it is not correct so that is a syntax error.

Logical Error-

Logical error is an error, which is extremely find to difficult in the program because they reflect the coding.we can say that logical error is bug which is in the source code such as operator precedence and any number divide by zero.
Let's see Example-

1)   int a=10.5;

2)   for(i=1;i<=10;i++);

Run-Time Error-

Run-time error is also indicate the bugs in the program at the run-time. For Example-

An integer divided by Zero.
int a=20/0;  //  here occurs run-time error.

In run-time error has two part or we can divided in two parts.

1) Handled Error.(It is also called an Exception Error.)

2) UN-handled Error.

Advantages-

Rest of the code is executed or normal flow of the program and an application is maintained.
For Example-

public class ExceptionExample{
public static void main(String[] args){
try{
int a=20/0;
}
catch(Exception e){
System.out.println("rest of the code");
}}
There are two type of Exception:-
1)  Checked.
2)  Unchecked.
Java Exception Hierarchy-