Difference Between Throw and Throws Keyword

Difference Between Throw and Throws Keyword

throw

throw is a keyword in java language which is used to throw any user defined exception to the same signature of method in which the exception is raised.

Note: throw keyword always should exist within method body.

whenever method body contain throw keyword than the call method should be followed by throws keyword.

Syntax

class className

{

returntype method(...) throws Exception_class

{

throw(Exception obj)

}

}

throws

throws is a keyword in java language which is used to throw the exception which is raised in the called method to it's calling method throws keyword always followed by method signature.

Example

returnType methodName(parameter)throws Exception_class....

{

.....

}

Difference between throw and throws

	throw	throws
1	throw is a keyword used for hitting and generating the exception which are occurring as a part of method body	throws is a keyword which gives an indication to the specific method to place the common exception methods as a part of try and catch block for generating user friendly error messages
2	The place of using throw keyword is always as a part of method body.	The place of using throws is a keyword is always as a part of method heading
3	When we use throw keyword as a part of method body, it is mandatory to the java programmer to write throws keyword as a part of method heading	When we write throws keyword as a part of method heading, it is optional to the java programmer to write throw keyword as a part of method body.

Example of throw and throws

Example

// save by DivZero.java

package pack;

public class DivZero

{

public void division(int a, int b)throws ArithmeticException

{

if(b==0)

{

ArithmeticException ae=new ArithmeticException("Does not enter zero for Denominator");

throw ae;

}

else

{

int c=a/b;

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

}

}

}

Compile: javac -d . DivZero.java

Example

// save by ArthException.java

import pack.DivZero;

import java.util.*;

class ArthException

{

public static void main(String args[])

{

System.out.println("Enter any two number: ");

Scanner s=new Scanner(System.in);

try

{

int a=s.nextInt();

int b=s.nextInt();

DivZero dz=new DivZero();

dz.division(a, b);

}

catch(Exception e)

{

System.err.println(e);

}

}

}

Compile: javac ArthException.java

Steps to Compile and Run code

First you save throw-example files into you PC in any where, here i will save this file in C:\>

·         C:\throw-example\>javac -d . DivZero.java

·         C:\throw-example\>javac ArthException.java

Note: First compile DivZero.java code then compile ArthException.java code