super Keyword Practice

Sample questions

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1. Sample 1difficulty 3/5

   <code>super(arg)</code> calls

   • A

     Compile error

   • B

     A static method

   • C

     The current class's other constructor

   • D

     The parent class constructor

     check_circle

   Why

   Use <code>super(args)</code> as first statement of subclass constructor.

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2. Sample 2difficulty 3/5

   public class A {
       public String hello() { return "Hi from A"; }
   }
   public class B extends A {
       public String hello() { return super.hello() + " and B"; }
   }
   System.out.println(new B().hello());

   What is printed?

   • A

     Stack overflow error

   • B

     and B

   • C

     Hi from A and B

     check_circle
   • D

     Hi from A

   Why

   <code>super.hello()</code> calls A's version, returning "Hi from A". Then " and B" is appended.

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3. Sample 3difficulty 3/5

   public class A {
       public String describe() { return "A"; }
   }
   public class B extends A {
       public String describe() { return super.describe() + "B"; }
   }
   public class C extends B {
       public String describe() { return super.describe() + "C"; }
   }
   // Usage:
   A obj = new C();
   System.out.print(obj.describe());

   What is printed?

   • A

     AC

   • B

     C

   • C

     ABC

     check_circle
   • D

     CBA

   Why

   C calls super.describe (B's), which calls super.describe (A's = "A"), then appends "B" → "AB", then appends "C" → "ABC".

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4. Sample 4difficulty 3/5

   public class A {
       public String label() { return "A"; }
       public String tag() { return label(); }
   }
   public class B extends A {
       public String label() { return "B"; }
   }
   // Usage:
   B b = new B();
   System.out.print(b.tag());

   What is printed?

   • A

     Compile error: tag missing in B

   • B

     AB

   • C

     A

   • D

     B

     check_circle

   Why

   tag() is inherited and calls label() (this.label()). Dynamic dispatch invokes B's label(), printing "B".

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5. Sample 5difficulty 3/5

   public class A {
       public String greet() { return "hello"; }
   }
   public class B extends A {
       public String greet() { return super.greet() + " world"; }
   }
   // Usage:
   B b = new B();
   System.out.print(b.greet());

   What is printed?

   • A

     world

   • B

     hello hello world

   • C

     hello world

     check_circle
   • D

     Stack overflow

   Why

   super.greet() calls A's greet returning "hello". B's greet appends " world", so "hello world" is printed.

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