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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.

Which of the following statements are true?
(A) A Java monitor must either extend Thread or implement Runnable.
(B) The sleep() method should be enclosed in try ... catch block.
(C) The yield() method should be enclosed in try ... catch block.
(D) A thread can be temporarily suspended from running by using the wait() method.
(E) A suspended thread using suspend() method can be revived using the resume() method.

  (C), (D) & (E)

  (A), (B) & (D)

  (D) & (E)

  (B), (D) & (E)

  (A), (B), (D) & (E)

  Half-n-half Clue
 

2.

Which of the following contain error?
(A) int x[] = int[10];
(B) int[] y = new int[5];
(C) float d[] =

  (A), (D) & (F)

  (A), (E) & (F)

  (A), (B), (D), (E) & (F)

  (D), (E) & (F)

  (A), (D) & (E)

  Half-n-half Clue
 

3.

Suppose that s1 and s2 are two strings. Which of the statements or expressions are valid?
(A) String s3 = s1 + s2;
(B) String s3 = s1 - s2;
(C) s1 <= s2
(D) s1.compareTo(s2);
(E) int m = s1.length();

  (A), (B) & (C)

  (C), (D) & (E)

  (A), (C) & (E)

  (D) & (E)

  (A), (D) & (E)

  Half-n-half Clue
 

4.

Given the following code:
class Base { int x = 10; }
class Derived extends Base
{ int x = 20; }

Base b = new Base();
Derived d = new Derived ( );
Base bd = new Derived();
The statement
System.out.println(b.x + " " + d.x + " " + bd.x);
will produce the output

  10 20 20

  20 10 20

  20 20 10

  10 20 10

  Half-n-half Clue
 

5.

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)

  (C), (D) & (E)

  (D) & (E)

  Half-n-half Clue
 

6.

When we implement the Runnable interface, we must define the method

  init()

  main()

  run()

  resume()

  start()

  Half-n-half Clue
 

7.

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

  java.lang.Object

  java.lang.Thread

  java.lang.Runnable

  java.lang.String

  java.lang.ThreadGroup

  Half-n-half Clue
 


 
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