Error and exception handling in java

Error:-

• Errors are the mistake. An error may produced incorrect result or terminate the execution of the program.

• Errors are like logical or typing mistakes.

Error have two different types:-

1. Compile time error:-  compile time error occur at compilation.This errors comes by typing mistakes.

                       Example:- System.out.println(Hello Java);

                       Error:-In above syntax double coutes are missing so this                                                            is called compile time error.

                      correct syntax:- System.out.println("Hello Java");

2.   Runtime error:-  Runtime error occur after successful compilation of program.This can happeen when logic is wrong(i.e result is mismatch).

Following are runtime error examples:-

• Dividing an integer by zero.
• passing a parameter to a method that is not in valid range or value.
• Attempting to use of negative size of array.
• Converting invalid string to a number.

Exception:-

• Exception is caused at runtime error in program.
• whenever java interpreter find an error such as dividing number by zero it creates an exception object and throws it to inform that an error has occurred.
• Java exception is an object.

Java can handled exception by using five keywords.

1.try     2.catch     3.throw   4.throws   5.finally

1.try:-  The statement due to which error can occur must be stored in the try block.if                 any one statement generates an exception within a try block then it is thrown.

2.catch:- The user code can catch this exception using catch and handle it properly.

3.throw:- If the user wants to manually throw an exception then throw keyword is                        used.

4.throws:- Any exception that is generated out of method must be specify by the                             throws clause.

5.finally:-  Any code that must be executed before method return is put in a finally                         block.

Example:-

public class ExceptionDemo {

public static void main(String[] args) {

   int a = 15;

   int b = 0;  

   

       try{

      int c = a/b;

      System.out.println("Result: "+c);

   }

   catch(ArithmeticException e){

System.out.println(e);

   }finally{

    System.out.println("always executes");

   }

   System.out.println("End");

}

}  

Output:-