Tag: java

Quizzes (35) Questions (265)

Questions Related to java

Multiple choice java

Which statement is true for the following code?

public class Plant {
   private String name;
   public Plant(String name) { this.name = name; }
   public String getName() { return name; }
}

public class Tree extends Plant {
   public void growFruit() { }
   public void dropLeaves() { }
}

  1. The code will compile without changes.

  2. The code will compile if public Tree() { Plant(); } is added to the Tree class.

  3. The code will compile if public Plant() { Tree(); } is added to the Plant class.

  4. The code will compile if public Plant() { this("fern"); } is added to the Plant class.
Reveal answer Fill a bubble to check yourself
D Correct answer
Full explanation
Multiple choice java

What will the result for following code?

public class Yikes {
    public static void go(Long n) {System.out.println("Long ");}
    public static void go(Short n) {System.out.println("Short ");}
    public static void go(int n) {System.out.println("int ");}

    public static void main(String [] args) {
        short y = 6;
        long z = 7;
        go(y);
        go(z);
    }
}

  1. int Long

  2. Short Long

  3. Compilation fails.

  4. An exception is thrown at runtime.
Reveal answer Fill a bubble to check yourself
A Correct answer
Full explanation
Multiple choice java

Which two, independently, will allow Sub to compile?

1. class Super {
2.   private int a;
3.   protected Super(int a) { this.a = a; }
4. }
...
11. class Sub extends Super {
12.   public Sub(int a) { super(a); }
13.   public Sub() { this.a = 5; }
14. }

  1. Change line 2 to: public int a;

  2. Change line 2 to :protected int a;

  3. Change line 13 to :public Sub() { this(5); }

  4. Change line 13 to :public Sub() { super(5); }
Reveal answer Fill a bubble to check yourself
C,D Correct answer
Full explanation
Multiple choice java

What will be the output?

public class Base {
  public static final String FOO = "foo";
  public static void main(String[] args) {
    Base b = new Base();
    Sub s = new Sub();
    System.out.print(Base.FOO);
    System.out.print(Sub.FOO);
    System.out.print(b.FOO);
    System.out.print(s.FOO);
    System.out.print(((Base)s).FOO);
  } 
}

class Sub extends Base {
    public static final String FOO="bar";
}

  1. foofoofoofoofoo

  2. foobarfoobarbar

  3. foobarfoofoofoo

  4. foobarfoobarfoo

  5. barbarbarbarbar
Reveal answer Fill a bubble to check yourself
D Correct answer
Full explanation
Multiple choice java

Which two statements are true?



    


    

      
    
          
  1. 
            
    An encapsulated, public class promotes re-use.
    
    
          
    2. 
          
  2. 
            
    Classes that share the same interface are always tightly encapsulated.
    
    
          
    3. 
          
  3. 
            
    An encapsulated class allows subclasses to overload methods, but does NOT allow overriding methods.
    
    
          
    4. 
          
  4. 
            
    An encapsulated class allows a programmer to change an implementation without affecting outside code.
    
    
          
    5. 
      

    


    

      Reveal answer
      Fill a bubble to check yourself
    


    

      

        A,D
        Correct answer
      

          

            Full explanation
          

    

  



      


      


    

      Multiple choice
        
              java

        
    


    

        
Which statement is true



public class CreditCard {

 private String cardID;
 private Integer limit;
 public String ownerName;

 public void setCardInformation(String cardID,
 String ownerName,
 Integer limit) {
  this.cardID = cardID;
  this.ownerName = ownerName;
  this.limit = limit;
 }
}



    


    

      
    
          
  1. 
            
    The class is fully encapsulated.
    
    
          
    2. 
          
  2. 
            
    The code demonstrates polymorphism.
    
    
          
    3. 
          
  3. 
            
    The ownerName variable breaks encapsulation.
    
    
          
    4. 
          
  4. 
            
    The cardID and limit variables break polymorphism.
    
    
          
    5. 
          
  5. 
            
    The setCardInformation method breaks encapsulation.
    
    
          
    6. 
      

    


    

      Reveal answer
      Fill a bubble to check yourself
    


    

      

        C
        Correct answer
      

          

            Full explanation