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Java Programming : Arrays and java.lang.* : Multiple Choice


Questions about arrays and classes in the java.lang package.

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Multiple choice

Your Performance  

1.

Given the code
String s = new String("abc");
Which of the following calls are valid?
(A) s.trim()
(B) s.replace('a', 'A')
(C) s.substring(3)
(D) s.toUppercase()
(E) s.setCharAt(1,'A')
(F) s.append("xyz")

  (A), (B), (C) & (D)

  (A), (C), (D) & (E)

  (A), (B) & (C)

  (D) & (E)

  (C), (D) & (E)

  Half-n-half Clue
 

2.

The methods wait() and notify() are defined in

  java.lang.ThreadGroup

  java.lang.Runnable

  java.lang.String

  java.lang.Object

  java.lang.Thread

  Half-n-half Clue
 

3.

Which of the following statements are valid array declaration?
(A) int number();
(B) float average[];
(C) double[] marks;
(D) counter int[];

  (A) & (C)

  (A)

  (D)

  (B) & (C)

  Half-n-half Clue
 

4.

Given the class definitions
class Base
{
void display ()
{ System.out.println("Base"); }
}
class Derived extends Base
{
void display ()
{ System.out.println("Derived"); }
}
and objects
Base b = new Base();
Derived d = new Derived();
Base bd = new Derived;

then the print statements
System.out.print(b.display() + " ");
System.out.print(d.display() + " ");
System.out.print(bd.display() + " ");
System.out.println();
will display:

  Base Base Derived

  Base Derived Derived

  Base Derived Base

  Derived Derived Derived

  Half-n-half Clue
 

5.

Consider the following code
int number[] = new int[5]; After execution of this statement, which of the following are true?
(A) number[0] is undefined
(B) number[5] is undefined
(C) number[4] is null
(D) number[2] is 0
(E) number.length() is 5

  (C) & (E)

  (E)

  (A) & (E)

  (B), (D) & (E)

  Half-n-half Clue
 

6.

Which of the following classes are available in the java.lang package?
(A) Stack
(B) Object
(C) Math
(D) Random
(E) String
(F) StringBuffer
(G) Vector

  (B), (C), (E) & (F)

  (A), (B), (C), (E) & (F)

  (C), (E) & (F)

  (B), (C) & (E)

  (B), (E) & (F)

  Half-n-half Clue
 

7.

Which of the following are the wrapper classes?
(A) Random
(B) Byte
(C) Vector
(D) Integer
(E) Short
(F) Double
(G) String

  (B), (D), (E) & (F)

  (A), (B), (D), (E) & (F)

  (B), (D) & (E)

  (D), (E) & (F)

  (B), (D) & (F)

  Half-n-half Clue
 


 
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