Declare or handle exception rule

[Tayitu Betule]

The following code is taken from K&B book. It prints out b. My question - isn't it a requirement for either the Slave class or main method to declare or handle the exception? What if doFileStuff() method throw the exception when called? Will the program die?

    

import java.io.*;

class Master{
	String doFileStuff() throws FileNotFoundException{
		return "a";
	}
}

class Slave extends Master{
	public static void main(String[] args){

		//exception not declared or handled in main		
		s=new Slave().doFileStuff();
		System.out.println(s);
	}

	//exception not declared or handled in Slave class
              String doFileStuff(){ return "b";}
}

Thank you all.

[Ankit Garg]

I don't think that program will compile as the type of s is not defined in main method. If we ignore that, the main method doesn't need to catch/declare in throws FileNotFoundException. You are calling doFileStuff of Slave class which doesn't declare any exceptions in its throws clause, so main method doesn't need to catch it. doFileStuff in Slave is a valid override of doFileStuff in Master, the overriding method can reduce the number of checked exceptions in the throws clause...

[Tayitu Betule]

Sorry... s was declared as a String in the program... typo error on my part.

Thank you for the explanation.

[Tayitu Betule]

I get it now... if we had s=new Master().doFileStuff(); in the main method instead of s=new Slave().doFileStuff(); then declare or handle exception rule must be enforced... otherwise compile time error.

Thank you Ankit.