Java Language | 10 Minute‐Test 18


Instruction

  • Total number of questions : 10.
  • Time alloted : 10 minutes.
  • Each question carry 1 mark.
  • No Negative marks
  • DO NOT refresh the page.
  • All the best :-).

1.

What is the output of this program?

    class box {

        int width;

        int height;

        int length;

    }     class mainclass {

        public static void main(String args[])

        {

                    box obj1 = new box();

            box obj2 = new box();

            obj1.height = 1;

            obj1.length = 2;

            obj1.width = 1;

            obj2 = obj1;

            System.out.println(obj2.height);

        }

    }

A.
1
B.
2
C.
Runtime error
D.
Garbage value

Your Answer: Option (Not Answered)

Correct Answer: Option A

Explanation:

When we assign an object to another object of same type, all the elements of right side object gets copied to object on left side of equal to, =, operator.

2.

In the below code, which call to sum() method is appropriate?

class Output {

         public static int sum(int ...x)

        {

             return;

        }

        static void main(String args[])

        {

                 sum(10);

             sum(10,20);

             sum(10,20,30);

             sum(10,20,30,40);

        }

}

A.
only sum(10)
B.
only sum(10,20)
C.
only sum(10) & sum(10,20)
D.
all of the mentioned

Your Answer: Option (Not Answered)

Correct Answer: Option D

Explanation:

sum is a variable argument method and hence it can take any number as argument.

3.

Which of the following statements are incorrect?

A.
default constructor is called at the time of object declaration
B.
Constructor can be parameterized
C.
finalize() method is called when a object goes out of scope and is no longer needed
D.
finalize() method must be declared protected

Your Answer: Option (Not Answered)

Correct Answer: Option C

Explanation:

finalize() method is called just prior to garbage collection. it is not called when object goes out of scope.

4.

What is the output of this program?

    class test {

        int a;

        int b;

        void meth(int i , int j) {

            i *= 2;

            j /= 2;

        }

              }

        class Output {

        public static void main(String args[])

        {

            test obj = new test();

      int a = 10;

            int b = 20;

                         obj.meth(a , b); 

           System.out.println(a + " " + b); 

               }  

   }

A.
10 20
B.
20 10
C.
20 40
D.
40 20

Your Answer: Option (Not Answered)

Correct Answer: Option A

Explanation:

Variables a & b are passed by value, copy of their values are made on formal parameters of function meth() that is i & j. Therefore changes done on i & j are not reflected back on original arguments. a & b remain 10 & 20 respectively.

5.

Which of these access specifier must be used for class so that it can be inherited by another sub class?

A.
public
B.
private
C.
protected
D.
None of the mentioned

Your Answer: Option (Not Answered)

Correct Answer: Option A

Explanation:

None.

6.

What is the output of this program?

    class Output {

        public static void main(String args[])

        {

            int arr[] = {1, 2, 3, 4, 5};

            for ( int i = 0; i < arr.length - 2; ++i)

                System.out.println(arr[i] + " ");

        }

    }

A.
1 2
B.
1 2 3
C.
1 2 3 4
D.
1 2 3 4 5

Your Answer: Option (Not Answered)

Correct Answer: Option B

Explanation:

arr.length() is 5, so the loop is executed for three times.

7.

What is the output of this program?

    class string_class

{

        public static void main(String args[])

        {

            String obj = "hello";

            String obj1 = "world";

               String obj2 = obj;

            obj2 = " world";

            System.out.println(obj + " " + obj2);

        }

    }

A.
hello hello
B.
world world
C.
hello world
D.
world hello

Your Answer: Option (Not Answered)

Correct Answer: Option C

Explanation:

None.

8.

What is the output of this program?

    class A {

        public int i;

        public int 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

Your Answer: Option (Not Answered)

Correct Answer: Option A

Explanation:

Keyword super is used to call constructor of class A by constructor of class B. Constructor of a initializes i & j to 1 & 2 respectively.

9.

What is the output of this program?

  class Abc

  {

      public static void main(String[]args)

      {

          String[] elements = { "for", "tea", "too" };

          String first = (elements.length > 0) ? elements[0]: null;

      }

  }

A.
Compilation error
B.
An exception is thrown at run time
C.
The variable first is set to null
D.
The variable first is set to elements[0].

Your Answer: Option (Not Answered)

Correct Answer: Option D

Explanation:

The value at the 0th position will be assigned to the variable first.

10.

What is the output of this program?

    class Output {

        public static void main(String args[])

        {

             Object obj = new Object();

       System.out.print(obj.getclass());

        }

    }

A.
Object
B.
class Object
C.
class java.lang.Object
D.
Compilation Error
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