OCPJP Simulation Test 7

7

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Question List

Question: What is the output of the following program?

  1 public abstract class Package {
  2   private String recipient;
  3   abstract void sendPackage();
  4   public static void main(String args[]) {
  5     Package email = new XyzPackage();
  6     email.recipient = "John Brown";
  7     email.sendPackage();
  8   }
  9   static class XyzPackage extends Package {
 10     public final void sendPackage()  {
 11       System.out.println("Package is sent to " + recipient);
 12     }}}

Choice:
A. Package is sent to
B. Package is sent to null
C. Package is sent to John Brown
D. Compilation error at line 2
E. Compilation error at line 5
F. Compilation error at line 9
G. Compilation error at line 10
H. Compilation error at line 11



Next Question

Answer: H

Explain: static nested class XyzPackage extends abstract class Package and overrides the abstract methods, which is a valid syntax. However, the enclosing class's private instance variable is not accessible by the static nested class. If the private modifier is removed from line 1, the answer will be C.

Study:  Develop code that uses abstract classes and methods

     Develop code that uses final keyword

     Create inner classes including static inner class, local class, nested class, and anonymous inner class