• August 29, 2014
  • Core Java
  • Comments Off on throws keyword in java

throws keyword in java

throws:

throws is used to throw an exception object implicitly. It is used with the method signature. More than one type of exception can be declared with method signature, they should be comma separated.

Note:
  1.  1. throws is mainly used to throw checked exception.
  2. 2. If you are calling a method that declares an exception, you must either caught or declare the exception.
  3. 3. We can rethrow the exception.

Syntax:

methodName () throws comma separated list of exceptionClassNames{}

Example:

ExceptionThrowsExample.java

/**
 * This program used to show the use of throws exception.
 * @author javawithease
 */
class ArithmaticTest{
	/**
	 * This method is used to divide two integers.
	 * @param num1
	 * @param num2
	 * @author javawithease
	 */
	public void division(int num1, int num2) 
                             throws ArithmeticException{
		//java.lang.ArithmeticException here.
		System.out.println(num1/num2);
	}
 
	public void method1(int num1, int num2) throws Exception{
		division(num1, num2);
	}
 
	public void method2(int num1, int num2){
		try{
			method1(num1, num2);
		}catch(Exception e){
			System.out.println("Exception Handled");
		}
	}
}
 
public class ExceptionThrowsExample {
	public static void main(String args[]){
		//creating ArithmaticTest object
		ArithmaticTest obj =  new ArithmaticTest();
 
		//method call
		obj.method2(20, 0);
	}
}

Output:

Exception Handled

Download this example.

 Difference between throw and throws.

                    throw keyword                     throws keyword
  1. 1. Used to explicitly throw an exception.
  2. 2. Only unchecked exception can propagate using throw.
  3. 3. Used within the method.
  4. 4. Cannot throw multiple exceptions.
  1. 1. Used to implicitly throw an exception.
  2. Both checked and unchecked exception can propagate using throws.
  3. 3. Used with the method signature.
  4. 4. Can declare multiple exceptions.

 
Next Topic: Exception propagation in java with example.
Previous Topic: throw in java with example.

Related Topics:

Some important terms for Exception Handling.
Exception handling in java.
try and catch blocks in java with example.
Multiple catch blocks in java with example.
Nested try block in java with example.
Finally in java with example.
throw in java with example.
throws in java with example.
Exception propagation in java with example.
Exception handling with method overriding in java.
Custom exception in java with example.
Commonly used exception methods of Throwable class in java.

 


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