50 Java Language MCQs with Answers

class Base {
    public void show() {
       System.out.println("Base::show() called");
    }
}
 
class Derived extends Base {
    public void show() {
       System.out.println("Derived::show() called");
    }
}
 
public class Main {
    public static void main(String[] args) {
        Base b = new Derived();;
        b.show();
    }
}

What is the use of final keyword in Java?

class Base {
    final public void show() {
       System.out.println("Base::show() called");
    }
}
 
class Derived extends Base {
    public void show() {
       System.out.println("Derived::show() called");
    }
}
 
class Main {
    public static void main(String[] args) {
        Base b = new Derived();;
        b.show();
    }
}

Which of the following is FALSE about arrays in Java?

package main;
class T {
  int t = 20;
}
class Main {
   public static void main(String args[]) {
      T t1 = new T();
      System.out.println(t1.t);
   }
}

class T {
  int t = 20;
  T() {
    t = 40;
  }
}
class Main {
   public static void main(String args[]) {
      T t1 = new T();
      System.out.println(t1.t);
   }
}

// file name: Main.java
public class Main {
    public static void main(String args[]) {
       int arr[] = {10, 20, 30, 40, 50};
       for(int i=0; i < arr.length; i++)
       {
             System.out.print(" " + arr[i]);              
       }
    }
}

Which of the following is true about interfaces in java.

1) An interface can contain following type of members.
....public, static, final fields (i.e., constants) 
....default and static methods with bodies

2) An instance of interface can be created.

3) A class can implement multiple interfaces.

4) Many classes can implement the same interface.