ExceptionHandling with MethodOverriding

ExceptionHandling with MethodOverriding

An overriding method (the method of child class) can throw any unchecked exceptions, regardless of whether the overridden method (method... 02:16

An overriding method (the method of child class) can throw any unchecked exceptions, regardless of whether the overridden method (method of base class) throws exceptions or not. However the overriding method should not throw checked exceptions that are new or broader than the ones declared by the overridden method. The overriding method can throw those checked exceptions, which have less scope than the exception(s) declared in the overridden method.

If the superclass method does not declare an exception

1) Rule: If the superclass method does not declare an exception, subclass overridden method cannot declare the checked exception.

import java.io.*;  
class Parent{  
  void msg(){System.out.println("parent");}  
}  
  
class TestExceptionChild extends Parent{  
  void msg()throws IOException{  
    System.out.println("TestExceptionChild");  
  }  
  public static void main(String args[]){  
   Parent p=new TestExceptionChild();  
   p.msg();  
  }  
}  

2) Rule: If the superclass method does not declare an exception, subclass overridden method cannot declare the checked exception but can declare unchecked exception.

import java.io.*;  
class Parent{  
  void msg(){System.out.println("parent");}  
}  
  
class TestExceptionChild1 extends Parent{  
  void msg()throws ArithmeticException{  
    System.out.println("child");  
  }  
  public static void main(String args[]){  
   Parent p=new TestExceptionChild1();  
   p.msg();  
  }  
}  

If the superclass method declares an exception

1) Rule: If the superclass method declares an exception, subclass overridden method can declare same, subclass exception or no exception but cannot declare parent exception.

import java.io.*;  
class Parent{  
  void msg()throws ArithmeticException{System.out.println("parent");}  
}  
  
class TestExceptionChild2 extends Parent{  
  void msg()throws Exception{System.out.println("child");}  
  
  public static void main(String args[]){  
   Parent p=new TestExceptionChild2();  
   try{  
   p.msg();  
   }catch(Exception e){}  
  }  
}