Java Constructors and Methods(1st) : Question 1 of 31

Determine output:

public class Test{
      public static void main(String args[]){
            MyClass obj = new MyClass();
            obj.val = 1;
            obj.call(obj);
            System.out.println(obj.val);
      }
}

class MyClass{
      public int val;
      public void call(MyClass ref){
            ref.val++;
      }
}

Determine output:

public class Test{
      public static void main(String args[]){
            MyClass obj = new MyClass();
            obj.val = 1;
            obj.call(obj);
            System.out.println(obj.val);
      }
}

class MyClass{
      public int val;
      public void call(MyClass ref){
            ref.val++;
      }
}

1 Mark(s)

Compilation Error
3
2
1
None of these

The implicit return type of a constructor is

1 Mark(s)

A class object in which it is defined.
void
There is no return type.
None of the above

What is the output for the below code ?

class A{
      public A(){
            System.out.println("A");
      }
      public A(int i){
            this();
            System.out.println(i);
      }
}
class B extends A{
      public B(){
            System.out.println("B");
      }
      public B(int i){
            this();
            System.out.println(i+3);
      }
}
public class Test{
      public static void main (String[] args){
            new B(5);
      }
}

What is the output for the below code ?

class A{
      public A(){
            System.out.println("A");
      }
      public A(int i){
            this();
            System.out.println(i);
      }
}
class B extends A{
      public B(){
            System.out.println("B");
      }
      public B(int i){
            this();
            System.out.println(i+3);
      }
}
public class Test{
      public static void main (String[] args){
            new B(5);
      }
}

1 Mark(s)

B 8 A 5
A B 8
None of these
A B 5
A 5 B 8

What is the expected output?

public class Profile {
	private Profile(int w) { // line 1
		System.out.print(w);
	}
	public final Profile() { // line 5
		System.out.print(10);
	}
	public static void main(String args[]) {
		Profile obj = new Profile(50);
	}
}

What is the expected output?

public class Profile {
	private Profile(int w) { // line 1
		System.out.print(w);
	}
	public final Profile() { // line 5
		System.out.print(10);
	}
	public static void main(String args[]) {
		Profile obj = new Profile(50);
	}
}

1 Mark(s)

10 50
Won't compile because of line (1); constructor can't be private
Won't compile because of line (5); constructor can't be final
50

Given the following piece of code:

class Person{
        public int number;
}
public class Test{
        public void doIt(int i , Person p){
                i = 5;
                p.number = 8;
        }
        public static void main(String args[]){
                int x = 0;
                Person p = new Person();
                new Test().doIt(x, p);
                System.out.println(x + " " + p.number);
        }
}

What is the result?

Given the following piece of code:

class Person{
        public int number;
}
public class Test{
        public void doIt(int i , Person p){
                i = 5;
                p.number = 8;
        }
        public static void main(String args[]){
                int x = 0;
                Person p = new Person();
                new Test().doIt(x, p);
                System.out.println(x + " " + p.number);
        }
}

What is the result?

1 Mark(s)

What will be the output?

public class Test{
      public static void main(String[] args){
            String value = "abc";
            changeValue(value);
            System.out.println(value);
      }

      public static void changeValue(String a){
            a = "xyz";
      }
}

What will be the output?

public class Test{
      public static void main(String[] args){
            String value = "abc";
            changeValue(value);
            System.out.println(value);
      }

      public static void changeValue(String a){
            a = "xyz";
      }
}

1 Mark(s)

Compilation fails
abc
Compilation clean but no output
None of these
xyz

Which of the modifier can't be used for constructors?

1 Mark(s)

static
protected
public
private

public class Test { }

What is the prototype of the default constructor?

public class Test { }

What is the prototype of the default constructor?

1 Mark(s)

None of these
public Test(void)
Test( )
Test(void)
public Test( )

What will be the result of compiling and running the given code?

class A{
      int b=10;
      private A(){
            this.b=7;
      }
      int f(){
            return b;
      }
}
class B extends A{
      int b;
}
public class Test{
      public static void main(String[] args){
            A a = new B();
            System.out.println(a.f());
      }
}

What will be the result of compiling and running the given code?

class A{
      int b=10;
      private A(){
            this.b=7;
      }
      int f(){
            return b;
      }
}
class B extends A{
      int b;
}
public class Test{
      public static void main(String[] args){
            A a = new B();
            System.out.println(a.f());
      }
}

1 Mark(s)

None of these
Compilation Fails
Prints 0
Prints 10
Prints 7

public class MyClass{ }

For the above class(MyClass) what is the correct way of declaring constructor?

public class MyClass{ }

For the above class(MyClass) what is the correct way of declaring constructor?

1 Mark(s)

MyClass(void) {}
MyClass(){}
1 and 3
public MyClass(void){}
public MyClass(){}

In which area of memory, the system stores parameters and local variables whenever a method is invoked?

1 Mark(s)

Storage Area
Array
Heap
Stack

Determine Output:

class A{
	public static void method(int i){
		System.out.print("Method 1");
	}

	public static int method(String str){
		System.out.print("Method 2");
		return 0;
	}
}

public class Test{
     
	public static void main(String args[]){
		A.method(5);
	}
}

Determine Output:

class A{
	public static void method(int i){
		System.out.print("Method 1");
	}

	public static int method(String str){
		System.out.print("Method 2");
		return 0;
	}
}

public class Test{
     
	public static void main(String args[]){
		A.method(5);
	}
}

1 Mark(s)

Compile time error as final method can't be overloaded
Method 1
Method 2
None of the above

What is the output for the below code ?

1. public class A{
2.       int add(int i, int j){
3.             return i+j;
4.       }
5. }
6. public class B extends A{
7.       public static void main(String argv[]){
8.             short s = 9;
9.             System.out.println(add(s,6));
10.      }
11.}

What is the output for the below code ?

1. public class A{
2.       int add(int i, int j){
3.             return i+j;
4.       }
5. }
6. public class B extends A{
7.       public static void main(String argv[]){
8.             short s = 9;
9.             System.out.println(add(s,6));
10.      }
11.}

1 Mark(s)

15
Compile fail due to error on line no 2
Compile fail due to error on line no 9
Compile fail due to error on line no 8
None of these

class MyClass{
	int i;
	int j;

	public MyClass(int i, int j){
		this.i = i;
		this.j = j;
	}

	public void call(){
		System.out.print("One");
	}
}

public class Test{
	public static void main(String args[]){
		MyClass m = new MyClass(); //line 1
		m.call(); //line 2
	}
}

class MyClass{
	int i;
	int j;

	public MyClass(int i, int j){
		this.i = i;
		this.j = j;
	}

	public void call(){
		System.out.print("One");
	}
}

public class Test{
	public static void main(String args[]){
		MyClass m = new MyClass(); //line 1
		m.call(); //line 2
	}
}

1 Mark(s)

Compilation succeed but no output.
One
Compilation fails due to an error on line 1
Compilation fails due to an error on line 2

What will be the return type of a method that not returns any value?

1 Mark(s)

int
None of the above
double
void

The variables declared in a class for the use of all methods of the class are called

1 Mark(s)

reference variables
objects
instance variables
None of these

What is the expected output?

class Animal {
	Animal() {
		System.out.println("Animal");
	}
}
class Wild extends Animal{
	Wild() {
		System.out.println("Wild");
		super();
	}
}
public class Test {
	public static void main(String args[]) {
		Wild wild = new Wild();
	}
}

What is the expected output?

class Animal {
	Animal() {
		System.out.println("Animal");
	}
}
class Wild extends Animal{
	Wild() {
		System.out.println("Wild");
		super();
	}
}
public class Test {
	public static void main(String args[]) {
		Wild wild = new Wild();
	}
}

1 Mark(s)

Runtime Exception
Wild Animal
Compilation Error
Animal Wild

class MyClass{
      MyClass(){
            System.out.print("one");
      }
      public void myMethod(){
            this();
            System.out.print("two");
      }
}
 
public class TestClass{
      public static void main(String args[]){
            MyClass obj = new MyClass();
            obj.myMethod();
      }
}

class MyClass{
      MyClass(){
            System.out.print("one");
      }
      public void myMethod(){
            this();
            System.out.print("two");
      }
}
 
public class TestClass{
      public static void main(String args[]){
            MyClass obj = new MyClass();
            obj.myMethod();
      }
}

1 Mark(s)

None of these
one Exception
Compilation Error
two one one
one one two

Which of the following statements regarding static methods are correct?
1. Static methods are difficult to maintain, because you can not change their implementation.
2. Static methods can be called using an object reference to an object of the class in which this method is defined.
3. Static methods are always public, because they are defined at class-level.
4. Static methods do not have direct access to non-static methods which are defined inside the same class.

1 Mark(s)

1 and 2
1 and 3
3 and 4
2 and 4

The finalize() method is called just prior to

1 Mark(s)

An object, variable or method goes out of scope.
None of the above
An object or variable goes out of scope.
Before garbage collection.
A variable goes out of scope.

class A{
      A(String s){}

      A(){}
}

1. class B extends A{
2.       B(){}
3.       B(String s){
4.             super(s);
5.       }
6.       void test(){
7.             // insert code here
8.       }
9. }

Which of the below code can be insert at line 7 to make clean compilation ?

class A{
      A(String s){}

      A(){}
}

1. class B extends A{
2.       B(){}
3.       B(String s){
4.             super(s);
5.       }
6.       void test(){
7.             // insert code here
8.       }
9. }

Which of the below code can be insert at line 7 to make clean compilation ?

1 Mark(s)

All of the above
None of these
A a = new B();
A a = new B(5);
A a = new A(String s);

Which of the following options is the best for generating random integer 0 or 1?

1 Mark(s)

(int)(Math.random() + 0.2)
(int)Math.random() + 1
(int)Math.random()
(int)(Math.random() + 0.5)

What is the output for the below code?

public class Test{
      public static void printValue(int i, int j, int k){
            System.out.println("int");
      }

      public static void printValue(byte...b){
            System.out.println("long");
      }

      public static void main(String... args){
            byte b = 9;
            printValue(b,b,b);
      }
}

What is the output for the below code?

public class Test{
      public static void printValue(int i, int j, int k){
            System.out.println("int");
      }

      public static void printValue(byte...b){
            System.out.println("long");
      }

      public static void main(String... args){
            byte b = 9;
            printValue(b,b,b);
      }
}

1 Mark(s)

None of these
int
Compilation fails
long
Compilation clean but throws RuntimeException

What is Math.floor(3.6)?

1 Mark(s)

Which of these is a legal definition of a method named examveda assuming it throws IOException, and returns void. Also assume that the method does not take any arguments. Select the one correct answer.

1 Mark(s)

void examveda() {} throws IOException
void examveda() throw IOException{}
examveda() throws IOException{}
void examveda() throws IOException{}
void examveda(void) throws IOException{}

What is the expected output?

public class Profile {
         private Profile(int w) { // line 1
                  System.out.print(w);
         }
         public static Profile() { // line 5
                  System.out.print (10);
         }
         public static void main(String args[]) {
                  Profile obj = new Profile(50);
         }
}

What is the expected output?

public class Profile {
         private Profile(int w) { // line 1
                  System.out.print(w);
         }
         public static Profile() { // line 5
                  System.out.print (10);
         }
         public static void main(String args[]) {
                  Profile obj = new Profile(50);
         }
}

1 Mark(s)

Won't compile because of line (1), constructor can't be private
Won't compile because of line (5), constructor can't be static
10 50
50

The main method should be static for the reason

1 Mark(s)

It can be executed without creating any instance of the class.
None of the above
It can be accessed easily by the class loader.
It can be accessed by every method or variable without any hindrance.

What is the output of the above program ?

class Num  {
      Num(double x ){
              System.out.println( x ) ;
      }   
}
public class  Test  extends  Num   {
       public static void main(String[] args){
                  Num num = new Num( 2 ) ;
       }     
}

What is the output of the above program ?

class Num  {
      Num(double x ){
              System.out.println( x ) ;
      }   
}
public class  Test  extends  Num   {
       public static void main(String[] args){
                  Num num = new Num( 2 ) ;
       }     
}

1 Mark(s)

Compile time error
2.0
0
None of the above

Determine output of the following program.

public class Test{
           public static void main(String args[]){
                  System.out.println( Math.floor( Math.random( ) ) ) ;
           }
}

Determine output of the following program.

public class Test{
           public static void main(String args[]){
                  System.out.println( Math.floor( Math.random( ) ) ) ;
           }
}

1 Mark(s)

0.0
10.0
1.0
0.5

What is the output of the program?

class Test{ 
        public int display(int x, int y){ 
                return ("The sum of x and y is " + x + y); 
        } 

        public static void main(String args[]){ 
                Test test = new Test();
                System.out.println(test.display(4,5)); 
        } 
}

What is the output of the program?

class Test{ 
        public int display(int x, int y){ 
                return ("The sum of x and y is " + x + y); 
        } 

        public static void main(String args[]){ 
                Test test = new Test();
                System.out.println(test.display(4,5)); 
        } 
}

1 Mark(s)

does not compile
None of the above
The sum of x and y is 45
The sum of x and y is 9

The following code contains one compilation error, find it?

public class Test {
	Test() {    }  // line 1
	static void Test() {  this(); } // line 2  
	public static void main(String[] args) { // line 3
		Test(); // line 4
	}
}

The following code contains one compilation error, find it?

public class Test {
	Test() {    }  // line 1
	static void Test() {  this(); } // line 2  
	public static void main(String[] args) { // line 3
		Test(); // line 4
	}
}

1 Mark(s)

At line 2, constructor call
At line 4
At line 1, constructor Tester must be marked public like its class
At line 3, compilation error, ambiguity problem, compiler can't determine whether a constructor