SCJP : Method overriding or overloading Mock Exam Practice Questions

Questions no -1 
What is the output for the below code ?

public class B {
	
	public String getCountryName(){
		return "USA";
	}
	
	public StringBuffer getCountryName(){
		StringBuffer sb = new StringBuffer();
		sb.append("UK");
		return sb;
	}
	
	
	public static void main(String[] args){
		B b = new B();
		System.out.println(b.getCountryName().toString());
	}

}



options
A)Compile with error
B)USA
C)UK
D) Runtime Exception

Correct answer is : A

Explanations : You cannot have two methods in the same class with signatures that only differ by return type.

Questions no -2 
What is the output for the below code ?

public class C {

}

public class D extends C{

}

public class A {
	
	public C getOBJ(){
		System.out.println("class A - return C");
		return new C();
		
	}

}

public class B extends A{
	
	public D getOBJ(){
		System.out.println("class B - return D");
		return new D();
		
	}

}

public class Test {

public static void main(String... args) {
     A a = new B();
     a.getOBJ();
	
     }
}



options
A)Compile with error - Not allowed to override the return type of a method with a subtype of the original type.
B)class A - return C
C)class B - return D
D) Runtime Exception

Correct answer is : C

Explanations : From J2SE 5.0 onwards. You are now allowed to override the return type of a method with a subtype of the original type.

Questions no -3 
What is the output for the below code ?

public class A {
	
	public String getName() throws ArrayIndexOutOfBoundsException{
		return "Name-A";
	}
	
}
	
public class C extends A{
	
	public String getName() throws Exception{
		return "Name-C";
	}

}
	
	
public class Test {
	public static void main(String... args) {
		A a = new C();
		a.getName();
	}
	
}



options
A)Compile with error
B)Name-A
C)Name-C
D)Runtime Exception

Correct answer is : A

Explanations : Exception Exception is not compatible with throws clause in A.getName().
Overridden method should throw only same or sub class of the exception thrown by super class method.