Java Test Set-1

What will be the output of the following Java program?

class selection_statements

{

public static void main(String args[])

{

int var1 = 5;

int var2 = 6;

if ((var2 = 1) == var1)

System.out.print(var2);

else

System.out.print(++var2);

}

1
2
3
4

What will be the output of the following Java program?

class comma_operator

{

public static void main(String args[])

{

int sum = 0;

for (int i = 0, j = 0; i < 5 & j < 5; ++i, j = i + 1)

sum += i;

System.out.println(sum);

}

5
6
14
compilation error

What will be the output of the following Java program?

class jump_statments

{

public static void main(String args[])

{

int x = 2;

int y = 0;

for ( ; y < 10; ++y)

{

if (y % x == 0)

continue;

else if (y == 8)

break;

else

System.out.print(y + ” “);

}

1 3 5 7
2 4 6 8
1 3 5 7 9
1 2 3 4 5 6 7 8 9

What will be the output of the following Java program?

class Output

{

public static void main(String args[])

{

final int a=10,b=20;

while(a<b)

{
System.out.println(“Hello”);

}

System.out.println(“World”);

}

Hello
run time error
Hello world
compile time error

What will be the output of the following Java program?

class Output

{

public static void main(String args[])

{

int a = 5;

int b = 10;

first:

{

second:

{

third:

{

if (a == b >> 1)

break second;

}

System.out.println(a);

}

System.out.println(b);

}

5 10
10 5
5
10

What would be the output of the following code snippet if variable a=10?

if(a<=0)

{

if(a==0)

{

System.out.println(“1 “);

}

else

{

System.out.println(“2 “);

}

System.out.println(“3 “);

1 2
2 3
1 3
3

What is true about a break?

Break stops the execution of entire program
Break halts the execution and forces the control out of the loop
Break forces the control out of the loop and starts the execution of next iteration
Break halts the execution of the loop for certain time frame

What is true about do statement?

do statement executes the code of a loop at least once
do statement does not get execute if condition is not matched in the first iteration
do statement checks the condition at the beginning of the loop
do statement executes the code more than once always

What will be the output of the following Java program?

class string_class

{

public static void main(String args[])

{

String obj = “hello”;

String obj1 = “world”;

String obj2 = “hello”;

System.out.println(obj.equals(obj1) + ” ” + obj.equals(obj2));

}

false false
false false
true false
true false

Which of these method of class String is used to compare two String objects for their equality?

equals()
Equals()
isequal()
Isequal()

What will be the output of the following Java code?

class output

{

public static void main(String args[])

{

String chars[] = {“a”, “b”, “c”, “a”, “c”};

for (int i = 0; i < chars.length; ++i)

for (int j = i + 1; j < chars.length; ++j)

if(chars[i].compareTo(chars[j]) == 0)

System.out.print(chars[j]);

}

ab
ab
ca
ac

What will be the output of the following Java program?

class main_class

{

public static void main(String args[])

{

int x = 9;

if (x == 9)

{

int x = 8;

System.out.println(x);

}

9
8
Compilation error
Runtime error

Which of the following statements is correct?

Public method is accessible to all other classes in the hierarchy
Public method is accessible only to subclasses of its parent class
Public method can only be called by object of its class
Public method can be accessed by calling object of the public class

What will be the output of the following Java program?

class box

{

int width;

int height;

int length;

}

class mainclass

{

public static void main(String args[])

{

box obj = new box();

obj.width = 10;

obj.height = 2;

obj.length = 10;

int y = obj.width * obj.height * obj.length;

System.out.print(y);

}

12
200
400
100

What will be the output of the following Java 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);

}

1
2
Runtime error
Garbage value

What will be the output of the following Java program?

class box

{

int width;

int height;

int length;

}

class mainclass

{

public static void main(String args[])

{

box obj = new box();

System.out.println(obj);

}

0
1
Runtime error
classname@hashcode in hexadecimal form

Which of these classes encapsulate runtime state of an object?

Class
System
Runtime
Cache

Which of these methods returns the class of an object?

getClass()
Class()
WhoseClass()
WhoseObject()

Which of these methods return a class object given its name?

getClass()
findClass()
getSystemClass()
findSystemClass()

Which of this class defines how the classes are loaded?

Class
System
Runtime
ClassLoader

What will be the output of the following Java program?

class X

{

int a;

double b;

}

class Y extends X

{

int c;

}

class Output

{

public static void main(String args[])

{

X a = new X();

Y b = new Y();

Class obj;

obj = a.getClass();

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

}

X
Y
a
b

What will be the output of the following Java program?

class X

{

int a;

double b;

}

class Y extends X

{

int c;

}

class Output

{

public static void main(String args[])

{

X a = new X();

Y b = new Y();

Class obj;

obj = b.getClass();

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

}

X
Y
class X
class Y

What will be the output of the following Java program?
class X

    {

        int a;

        double b;

    }

    class Y extends X

    {

            int c;

    }

    class Output

    {

        public static void main(String args[])

        {

            X a = new X();

            Y b = new Y();

            Class obj;

            obj = b.getClass();

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

        }

    }

0
1
true
false

Which method can be defined only once in a program?

main method
finalize method
static method
private method

Which of this statement is incorrect?

All object of a class are allotted memory for the all the variables defined in the class
If a function is defined public it can be accessed by object of other class by inheritation
main() method must be made public
All object of a class are allotted memory for the methods defined in the class

What will be the output of the following Java program?

class box

{

int width;

int height;

int length;

int volume;

void volume(int height, int length, int width)

{

volume = width*height*length;

}

class Prameterized_method

{

public static void main(String args[])

{

box obj = new box();

obj.height = 1;

obj.length = 5;

obj.width = 5;

obj.volume(3,2,1);

System.out.println(obj.volume);

}

0
1
6
25

What will be the output of the following Java program?

class equality

{

int x;

int y;

boolean isequal()

{

return(x == y);

}

class Output

{

public static void main(String args[])

{

equality obj = new equality();

obj.x = 5;

obj.y = 5;

System.out.println(obj.isequal());

}

false
true
0
1

What will be the output of the following Java program?

class box

{

int width;

int height;

int length;

int volume;

void volume()

{

volume = width*height*length;

}

class Output

{

public static void main(String args[])

{

box obj = new box();

obj.height = 1;

obj.length = 5;

obj.width = 5;

obj.volume();

System.out.println(obj.volume);

}

0
1
25
26

In the following Java 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);

}

only sum(10)
only sum(10,20)
only sum(10) & sum(10,20)
all of the mentioned

What will be the output of the following Java program?

class area {

int width;

int length;

int volume;

area()

{

width=5;

length=6;

}

void volume()

{

volume = width*length*height;

}

class cons_method

{

public static void main(String args[])

{

area obj = new area();

obj.volume();

System.out.println(obj.volume);

}

0
1
30
error

What is the return type of Constructors?

int
float
void
none of the mentioned

Which keyword is used by the method to refer to the object that invoked it?

import
catch
abstract
this

Which of the following is a method having same name as that of its class?

finalize
delete
class
constructor

Which operator is used by Java run time implementations to free the memory of an object when it is no longer needed?

delete
free
new
none of the mentioned

Which function is used to perform some action when the object is to be destroyed?

finalize()
delete()
main()
none of the mentioned

What will be the output of the following Java code?

class box

{

int width;

int height;

int length;

int volume;

box()

{

width = 5;

height = 5;

length = 6;

}

void volume()

{

volume = width*height*length;

}

class constructor_output

{

public static void main(String args[])

{

box obj = new box();

obj.volume();

System.out.println(obj.volume);

}

100
150
200
250

What will be the output of the following Java code?

class San

{

San()throws IOException

{

}

class Foundry extends San

{

Foundry()

{

}

public static void main(String[]args)

{

}

compile time error
run time error
compile and runs fine
unreported exception java.io.IOException in default constructor

What will be the output of the following Java code?

class box {

int width;

int height;

int length;

int volume;

void finalize()

{

volume = width*height*length;

System.out.println(volume);

}

protected void volume()

{

volume = width*height*length;

System.out.println(volume);

}

class Output

{

public static void main(String args[])

{

box obj = new box();

obj.width=5;

obj.height=5;

obj.length=6;

obj.volume();

}

150
200
Run time error
Compilation error

Which of the following statements are incorrect?

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

What will be the output of the following Java code?

class area

{

int width;

int length;

int area;

void area(int width, int length)

{

this.width = width;

this.length = length;

}

class Output

{

public static void main(String args[])

{

area obj = new area();

obj.area(5 , 6);

System.out.println(obj.length + ” ” + obj.width);

}

0 0
5 6
6 5
5 5

What is true about private constructor?

Private constructor ensures only one instance of a class exist at any point of time
Private constructor ensures multiple instances of a class exist at any point of time
Private constructor eases the instantiation of a class
Private constructor allows creating objects in other classes

What would be the behaviour if this() and super() used in a method?

Runtime error
Throws exception
compile time error
Runs successfully

What is false about constructor?

Constructors cannot be synchronized in Java
Java does not provide default copy constructor
Constructor can have a return type
“this” and “super” can be used in a constructor

What is true about Class.getInstance()?

Class.getInstance calls the constructor
Class.getInstance is same as new operator
Class.getInstance needs to have matching constructor
Class.getInstance creates object if class does not have any constructor

What is true about constructor?

It can contain return type
It can take any number of parameters
It can have any non access modifiers
Constructor cannot throw an exception

Abstract class cannot have a constructor

True
False
Error
Exception

What is true about protected constructor?

Protected constructor can be called directly
Protected constructor can only be called using super()
Protected constructor can be used outside package
protected constructor can be instantiated even if child is in a different package

What is not the use of “this” keyword in Java?

Passing itself to another method
Calling another constructor in constructor chaining
Referring to the instance variable when local variable has the same name
Passing itself to method of the same class

What would be the behaviour if one parameterized constructor is explicitly defined?

Compilation error
Compilation succeeds
Runtime error
Compilation succeeds but at the time of creating object using default constructor, it throws compilation error

What would be behaviour if the constructor has a return type?

Compilation error
Runtime error
Compilation and runs successfully
Only String return type is allowed

Java Test Set-1

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