TEST YOUR JAVA KNOWLEDGE

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TEST YOUR JAVA KNOWLEDGE
1.What will be the output of the program?
class s implements Runnable
{
    int x, y;
    public void run()
    {
        for(int i = 0; i < 1000; i++)
            synchronized(this)
            {
                x = 12;
                y = 12;
            }
        System.out.print(x + " " + y + " ");
    }
    public static void main(String args[])
    {
        s run = new s();
        Thread t1 = new Thread(run);
        Thread t2 = new Thread(run);
        t1.start();
        t2.start();
    }
}
A) DeadLock
B) It print 12 12 12 12
C) Compilation Error
D) Cannot determine output.

2.Which one of these lists contains only Java programming language keywords?
A) class, if, void, long, Int, continue
B) goto, instanceof, native, finally, default, throws
C) try, virtual, throw, final, volatile, transient
D) strictfp, constant, super, implements, do
E) byte, break, assert, switch, include

3.public void test(int x)
  {
    int odd = 1;
    if(odd) /* Line 4 */
    {
        System.out.println("odd");
    }
    else
    {
        System.out.println("even");
    }
 }
Which statement is true?
A) Compilation fails.
B) "odd" will always be output.
C) "even" will always be output.
D) "odd" will be output for odd values of x, and "even" for even values.

4.What will be the output of the program?
public class SwitchTest
{ 
    public static void main(String[] args)
    {
        System.out.println("value =" + switchIt(4));
    }
    public static int switchIt(int x)
    {
        int j = 1; 
        switch (x)
        {
            case 1: j++;
            case 2: j++; 
            case 3: j++;
            case 4: j++;
            case 5: j++;
            default: j++;
            }
        return j + x; 
    }
}
A) value = 2
B) value = 4
C) value = 6
D) value = 8

5.Which constructs an anonymous inner class instance?
A) Runnable r = new Runnable() { };
B) Runnable r = new Runnable(public void run() { });
C) Runnable r = new Runnable { public void run(){}};
D) System.out.println(new Runnable() {public void run() { }});

6. class Boo
   {
    Boo(String s) { }
    Boo() { }
   }
   class Bar extends Boo
   {
    Bar() { }
    Bar(String s) {super(s);}
    void zoo()
    {
    // insert code here
    }
   }
which one create an anonymous inner class from within class Bar?
A) Boo f = new Boo(24) { };
B) Boo f = new Bar() { };
C) Bar f = new Boo(String s) { };
D) Boo f = new Boo.Bar(String s) { };

7.What will be the output of the program?
  class PassS
  {
    public static void main(String [] args)
    {
        PassS p = new PassS();
        p.start();
    }

    void start()
    {
        String s1 = "slip";
        String s2 = fix(s1);
        System.out.println(s1 + " " + s2);
    }

    String fix(String s1)
    {
        s1 = s1 + "stream";
        System.out.print(s1 + " ");
        return "stream";
    }
  }
A) slip stream
B) slipstream stream
C) stream slip stream
D) slipstream slip stream

8.What will be the output of the program?
  public class Test
  {  
    public static void leftshift(int i, int j)
    {
        i <<= j;
    }
    public static void main(String args[])
    {
        int i = 4, j = 2;
        leftshift(i, j);
        System.out.printIn(i);
    }
  }
A) 2
B) 4
C) 8
D) 16

9.What is the value returned by function compareTo() if the invoking string is less than the string compared?
A) zero
B) value less than zero
C) value greater than zero
D) None of the mentioned

10. Which of these class is implemented by FilterInputStream class?
A) InputStream
B) BufferedInputStream
C) FileInputStream
D) BufferedFileInputStream

11. Which of these class contains the methods print() & println()?
A) System
B) System.out
C) BUfferedOutputStream
D) PrintStream

12. Which of these is specified by a File object?
A)      a file in disk
B)      directory path
C)      directory in disk
D)      None of the mentioned

13. Which of these is a mechanism for naming and visibility control of a class and its content?
A)     Object
B)     Packages
C)     Interfaces
D)     None of the Mentioned.

14. Which of the following is incorrect statement about packages?
A)     Package defines a namespace in which classes are stored.
B)     A package can contain other package within it.
C)     Java uses file system directories to store packages.
D)     A package can be renamed without renaming the directory in which the classes are stored.

15.What is the order of precedence (highest to lowest) of following operators?
 1. &
 2. ^
 3. ?:
A)      1 -> 2 -> 3
B)      2 -> 1 -> 3
C)      3 -> 2 -> 1
D)      2 -> 3 -> 1

16. What is the output of this program?
    class A {
            public int i,j;
        A() {
            i = 1;
            j = 2;
               }
     }   
    class B extends A{
      int a;
      B() {
      super();
       }
      }   
     class super_use{  
     public static void main(String args[])
        {
            B obj = new B();
            System.out.println(obj.i + " " + obj.j)    
        }
   }
A) 1 2
B) 2 1
C) Runtime Error
D) Compilation Error

17. What is the output of this program?
    abstract class A {
        int i;
        abstract void display();
    }   
    class B extends A {
        int j;
        void display() {
            System.out.println(j);
        }
    }   
    class Abstract_demo {
        public static void main(String args[])
        {
            B obj = new B();
            obj.j=2;
            obj.display();   
        }
   }
A) 0
B) 2
C) Runtime Error
D) Compilation Error

18. Which of the following is incorrect statement regarding the use of generics and parameterized types in Java? A) Generics provide type safety by shifting more type checking responsibilities to the compiler.
B) Generics and parameterized types eliminate the need for down casts when using Java Collections.
C) When designing your own collections class (say, a linked list), generics and parameterized types allow you to achieve type safety with just a single class definition as opposed to defining multiple classes.
D) All of the mentioned

19. Which of the following keywords are used for lower bounding a wild card? A) extends
B) super
C) class
D) lower

20. Which of these method of Locale class can be used to obtain country of operation? A) getCountry()
B) whichCountry()
C) DisplayCountry()
D) getDisplayCountry()

21. Which of these methods can be used to know which key is pressed? A) getKey()
B) getModifier()
C) getActionKey()
D) getActionEvent()

22. How many bits are used to represent Unicode ? A) 8 bits
B) 16 bits
C) 24 bits
D) 32 bits

23. Which of the following is not type of inner classes ? A) Simple Inner Class
B) Static Nested Inner Class
C) Method Nested Static Inner Class
D) Anonymous Inner Class

24. Choose the proper operator precedence when evaluating an Expression?
1. Comparisons
2. Logical operations
3. Increment
4. Arithmetic operations
A) 3-4-1-2
B) 1-2-4-3
C) 4-3-1-2
D) 2-1-4-3

25. Java is designed for the distributed environment of the Internet, because it handles ________ protocols
A) UDP
B) TCP/IP
C) FTP
D) TEL

26. x=10,y=5
      if(x>=9&&y<=8)
 z=x+y
      else
            z=x-y
What would be value of z after executing the following statement
A)     15 
B)     5
C)     13      
D)     none of these

27.The _______ keyword is used to derive a class from a superclass. The _________keyword is used to declare classes that define common properties and behavior of other classes
A) Public ,friend
B) abstract ,extends ,
C) extends,abstract
D) friend ,Public

28. A class can be declared as _______ if you do not want the class to be subclassed. Using the __________ keyword we can abstract a class interface from its implementation.
A) protected ,interface
B) final,interface
C) public,friend
D) final,protected

29. The term exception denotes an ________ event .Java handles exceptions the___________ way.

A) exceptional ,object-oriented

B) traditional, object-oriented
C) exceptional, procedural
D) friend ,Public


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