Throws Keyword Example in Java

Here we will see few examples of throws keyword. To understand these programs you should have the knowledge of throws keyword in java.

Example 1: Exception propagation using throws keyword

As you can see that we have an exception occurred in method1 which has been handled in the chain-calling method method3(). This example shows how exception propagation works.

class Example1{  
   void method1() throws ArithmeticException{  
	throw new ArithmeticException("Calculation error"); 
   }  
   void method2() throws ArithmeticException{  
	method1();  
   }  
   void method3(){  
	try{  
	   method2();  
	}
	catch(ArithmeticException e){
	   System.out.println("ArithmeticException handled");
	}  
   }  
   public static void main(String args[]){  
	Example1 obj=new Example1();  
	obj.method3();  
	System.out.println("End Of Program");  
   }  
}

Output:

ArithmeticException handled
End Of Program

Example 2: When you don’t handle exception and instead declare it at all the places

The ideal way to use throws is by declaring the exceptions in method signature and handle the exceptions using try-catch in calling method. Lets see what happens when we declare the exception at both the places, in method signature as well as in calling method.

class ExceptionExample{  
 void method()throws ArithmeticException{  
  throw new ArithmeticException("ArithmeticException Occurred");  
 }  
}  
class Example1{  
   public static void main(String args[])throws ArithmeticException{
     ExceptionExample obj=new ExceptionExample();  
     obj.method();  
  
    System.out.println("End Of Program");  
  }  
}

Output:

Exception in thread "main" java.lang.ArithmeticException: 
ArithmeticException Occurred
at ExceptionExample.method(Example1.java:4)
at Example1.main(Example1.java:10)