Saturday, May 8, 2021

Java Output Interview Questions And Answer

 Technical Programming Output Questions

1. 

// filename Main.java

class Test {

    protected int x, y;

}

  

class Main {

    public static void main(String args[]) {

        Test t = new Test();

        System.out.println(t.x + " " + t.y);

    }

}

 

2.

// filename Test.java

class Test {

    public static void main(String[] args) {

        for(int i = 0; 1; i++) {

            System.out.println("Hello");

            break;

        }

    }

}

 

3.

class Main {

    public static void main(String args[]) {   

        System.out.println(fun());

    } 

    int fun() {

        return 20;

    } 

}

 

4.

class Test {

   public static void main(String args[]) {

       System.out.println(fun());

   }

   static int fun() {

       static int x= 0;

       return ++x;

   }

}

 

5.

package main;

  

class Base {

    public void Print()

    {

        System.out.println("Base");

    }

}

  

class Derived extends Base {

    public void Print()

    {

        System.out.println("Derived");

    }

}

  

class Main {

    public static void DoPrint(Base o)

    {

        o.Print();

    }

    public static void main(String[] args)

    {

        Base x = new Base();

        Base y = new Derived();

        Derived z = new Derived();

        DoPrint(x);

        DoPrint(y);

        DoPrint(z);

    }

}

 

6.

package main;

  

// filename Main.java

class Point {

    protected int x, y;

  

    public Point(int _x, int _y)

    {

        x = _x;

        y = _y;

    }

}

  

public class Main {

    public static void main(String args[])

    {

        Point p = new Point();

        System.out.println("x = " + p.x + ", y = " + p.y);

    }

}

 

7.

class Test {   

    int y = 2;

    int x  = y+2; 

    public static void main(String[] args) {   

         Test m = new Test();

         System.out.println("x = " + m.x + ", y = " + m.y);

    }

}

 

8.

public class Test

{   

    int x = 2;

    Test(int i) { x = i; }

    public static void main(String[] args) {   

         Test t = new Test(5);

         System.out.println("x = " + t.x);

    }

}

 

9.

public class Calculator

{

    int num = 100;

    public void calc(int num)  { this.num = num * 10;  }

    public void printNum()     { System.out.println(num); }

  

    public static void main(String[] args)

    {

        Calculator obj = new Calculator();

        obj.calc(2);

        obj.printNum();

    }

}

 

10.

public class MyStuff

{

    String name;

  

    MyStuff(String n) {  name = n;  }

  

    public static void main(String[] args)

    {

        MyStuff m1 = new MyStuff("guitar");

        MyStuff m2 = new MyStuff("tv");

        System.out.println(m2.equals(m1));

    }

  

    @Override

    public boolean equals(Object obj)

    {

        MyStuff m = (MyStuff) obj;

        if (m.name != null)  { return true;  }

        return false;

    }

}

 

11.

public class Test

{

    public static void main(String[] args)

    {

        StringBuilder s1 = new StringBuilder("Java");

        String s2 = "Love";

        s1.append(s2);

        s1.substring(4);

        int foundAt = s1.indexOf(s2);

        System.out.println(foundAt);

    }

}

 

12.

class Writer

{

                public static void write()

                {

                                System.out.println("Writing...");

                }

}

class Author extends Writer

{

                public static void write()

                {

                                System.out.println("Writing book");

                }

}

 

public class Programmer extends Author

{

                public static void write()

                {

                                System.out.println("Writing code");

                }

 

                public static void main(String[] args)

                {

                                Author a = new Programmer();

                                a.write();

                }

}

13.

class First

{

                public First() { System.out.println("a"); }

}

 

class Second extends First

{

                public Second() { System.out.println("b"); }

}

 

class Third extends Second

{

                public Third() { System.out.println("c"); }

}

 

public class MainClass

{

                public static void main(String[] args)

                {

                                Third c = new Third();

                }

}

14.

class First

{

                int i = 10;

 

                public First(int j)

                {

                                System.out.println(i);

                                this.i = j * 10;

                }

}

 

class Second extends First

{

                public Second(int j)

                {

                                super(j);

                                System.out.println(i);

                                this.i = j * 20;

                }

}

 

public class MainClass

{

                public static void main(String[] args)

                {

                                Second n = new Second(20);

                                System.out.println(n.i);

                }

}

15.

import java.util.*;

class I

{

                public static void main (String[] args)

                {

                                Object i = new ArrayList().iterator();

                                System.out.print((i instanceof List) + ", ");

                                System.out.print((i instanceof Iterator) + ", ");

                                System.out.print(i instanceof ListIterator);

                }

}

16.

class ThreadEx extends Thread

{

                public void run()

                {

                                System.out.print("Hello...");

                }

                public static void main(String args[])

                {

                                ThreadEx T1 = new ThreadEx();

                                T1.start();

                                T1.stop();

                                T1.start();

                }

}

17.

public class Test

{

                public int getData() //getdata() 1

                {

                                return 0;

                }

                public long getData() //getdata 2

                {

                                return 1;

                }

                public static void main(String[] args)

                {

                                Test obj = new Test();

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

                }

}

18.

public class Test

{

                public int getData(String temp) throws IOException

                {

                                return 0;

                }

                public int getData(String temp) throws Exception

                {

                                return 1;

                }

                public static void main(String[] args)

                {

                                Test obj = new Test();

                                System.out.println(obj.getData("GFG"));

                }

}

19.

class Derived

{

                protected final void getDetails()

                {

                                System.out.println("Derived class");

                }

}

 

public class Test extends Derived

{

                protected final void getDetails()

                {

                                System.out.println("Test class");

                }

                public static void main(String[] args)

                {

                                Derived obj = new Derived();

                                obj.getDetails();

                }

}

20.

class Derived

{

                public void getDetails(String temp)

                {

                                System.out.println("Derived class " + temp);

                }

}

 

public class Test extends Derived

{

                public int getDetails(String temp)

                {

                                System.out.println("Test class " + temp);

                                return 0;

                }

                public static void main(String[] args)

                {

                                Test obj = new Test();

                                obj.getDetails("GFG");

                }

}

21.

Which methods are provided by the PrintStream class?

a. Read data to another stream
b. Write data to another stream
c. Read data to same stream
d. Write data to same stream

22.

Daemon thread provides services to user threads for background supporting tasks,It has no role in life than to serve user threads.

a. True
b. False

23.

class Helper

{

                private int data;

                private Helper()

                {

                                data = 5;

                }

}

public class Test

{

                public static void main(String[] args)

                {

                                Helper help = new Helper();

                                System.out.println(help.data);

                }

}

 

24.

 

public class Test implements Runnable

{

                public void run()

                {

                                System.out.printf(" Thread's running ");

                }

 

                try

                {

                                public Test()

                                {

                                                Thread.sleep(5000);

                                }

                }

                catch (InterruptedException e)

                {

                                e.printStackTrace();

                }

               

                public static void main(String[] args)

                {

                                Test obj = new Test();

                                Thread thread = new Thread(obj);

                                thread.start();

                                System.out.printf(" GFG ");

                }

}

25.

public class Test

{

                public Test()

                {

                                System.out.printf("1");

                                new Test(10);

                                System.out.printf("5");

                }

                public Test(int temp)

                {

                                System.out.printf("2");

                                new Test(10, 20);

                                System.out.printf("4");

                }

                public Test(int data, int temp)

                {

                                System.out.printf("3");

                               

                }

               

                public static void main(String[] args)

                {

                                Test obj = new Test();

                               

                }

               

}

 

26.

class demo1 {

                public static void main(String args[])

                {

                                String str1 = "java";

                                char arr[] = { 'j', 'a', 'v', 'a', ' ', 'p',

                                'r', 'o', 'g', 'r', 'a', 'm', 'm', 'i', 'n', 'g' };

                                String str2 = new String(arr);

                                System.out.println(str1);

                                System.out.println(str2);

                }

}

27.

class demo2 {

                public static void main(String args[])

                {

                                String str1 = "";

                                char arr[] = { 'j', 'a', 'v', 'a', ' ', 'p',

                                'r', 'o', 'g', 'r', 'a', 'm', 'm', 'i', 'n', 'g' };

                                String str2 = new String(arr);

                                String str3 = new String(str2);

 

                                System.out.println(str1);

                                System.out.println(str2);

                                System.out.println(str3);

                }

}

28.

class demo3 {

                public static void main(String args[])

                {

                                byte[] arr = { 97, 98, 99, 100, 101 };

                                String str2 = new String(arr);

 

                                System.out.println(str2);

                }

}

29.

class demo4 {

                public static void main(String args[])

                {

                                String str = "Java Programming";

                                char ch = str.charAt(2);

                                System.out.println(ch);

                }

}

30.

class demo5 {

                public static void main(String args[])

                {

                                String str = "Java Programming";

                                char arr[] = new char[10];

                                str.getChars(0, 4, arr, 0);

                                System.out.println(arr);

                }

}

31.

class demo7 {

                public static void main(String args[])

                {

                                String str = "Java Programming";

                                String str1 = "Java Programming";

 

                                String str2 = str1;

                                if (str.equals(str1))

                                                System.out.println("Equal Case 1");

                                if (str == str1)

                                                System.out.println("Equal Case 2");

                }

}

32.

class demo8 {

                public static void main(String args[])

                {

                                String str = "Java Programming";

                                String str1 = "Programminggggg";

 

                                if (str.regionMatches(5, str1, 0, 11))

                                                System.out.println("Same");

                }

}

33.

class demo9 {

                public static void main(String args[])

                {

                                String str = "Java Programming";

                                String str1 = "Java";

                                if (str.startsWith("J"))

                                                System.out.println("Start Same");

 

                                if (str.endsWith("T"))

                                                System.out.println("End Same");

                }

}

34.

class demo10 {

                public static void main(String args[])

                {

                                String str = "JavaProgramming";

                                String str1 = "Java";

 

                                System.out.println(str.compareTo(str1));

                                System.out.println(str1.compareTo(str));

                }

}

35.

class demo12 {

                public static void main(String args[])

                {

                                String str = "Java Programming";

                                String str1 = "Java";

                                String str2 = str.substring(5);

                                System.out.println(str2);

                                System.out.println(str.substring(5, 9));

                }

}

36.

import java.util.*;

 

public class Treeset {

                public static void main(String[] args)

                {

                                TreeSet<String> treeSet = new TreeSet<>();

 

                                treeSet.add("Free");

                                treeSet.add("For");

                                treeSet.add("Java Training");

                                treeSet.add("Free For Java Training");

 

                                for (String temp : treeSet)

                                                System.out.printf(temp + " ");

 

                                System.out.println("\n");

                }

}

37.

public class MyFirst {  

      public static void main(String[] args) {  

         MyFirst obj = new MyFirst(n);  

 }  

 static int a = 10;  

 static int n;  

 int b = 5;  

 int c;  

 public MyFirst(int m) {  

       System.out.println(a + ", " + b + ", " + c + ", " + n + ", " + m);  

   }  

// Instance Block  

  {  

     b = 30;  

     n = 20;  

  }   

// Static Block  

  static   

{  

          a = 60;  

     }   

 }  

 

38.

public class testincr
{
public static void main(String args[])
{
int i = 0;
i = i++ + i;
System.out.println(“I = ” +i);
}
}

39.

public class testmeth
{
static int i = 1;
public static void main(String args[])
{
System.out.println(i+” , “);
m(i);
System.out.println(i);
}
public void m(int i)
{
i += 2;
}
}

 

40.

Consider the two methods (within the same class)
public static int foo(int a, String s)
{
s = “Yellow”;
a=a+2;
return a;
}
public static void bar()
{
int a=3;
String s = “Blue”;
a = foo(a,s);
System.out.println(“a=”+a+” s=”+s);
}
public static void main(String args[])
{
bar();
}

41)Among these expressions, which is(are) of type String?

(a) “0” (b) “ab” + “cd”
(c) ‘0’
(d) Both (A) and (B) above (e) (A), (B) and (C) above.

42) Consider the following code fragment
Rectangle r4 = new Rectangle();
r4.setColor(Color.blue);
Rectangle r2 = r4;
r2.setColor(Color.red);

After the above piece of code is executed, what are the colors of r4 and
r2 (in this order)?

(a) Color.blue
Color.red
(b) Color.blue
Color.blue
(c) Color.red
Color.red
(d) Color.red
Color.blue
(e) None of the above.

43) What is the type and value of the following expression? (Notice the integer division)
-4 + 4/2 + 2*-3 + 5.0

(a) int -5 (b) double -4.5
(c) int -4
(d) double -5.0 (e) None of the above.

44) What is printed by the following statement?
System.out.print(“Hello,\nworld!”);

(a) Hello, \nworld! (b) Hello, world!
(c)
(d) “Hello, \nworld!” (e) None of the above.

45) Consider the two methods (within the same class)
public static int foo(int a, String s)
{
s = “Yellow”;
a=a+2;
return a;
}
public static void bar()
{
int a=3;
String s = “Blue”;
a = foo(a,s);
System.out.println(“a=”+a+” s=”+s);
}
public static void main(String args[])
{
bar();
}

What is printed on execution of these methods?

(a) a = 3 s = Blue (b) a = 5 s = Yellow (c) a = 3 s = Yellow
(d) a = 5 s = Blue (e) none of the above.

46) Which of the following variable declaration would NOT compile in a java program?

(a) int var; (b) int VAR; (c) int var4; (d) int var_4; (e) int 4_var;.

47) Consider the following class definition:

public class MyClass
{
private int value;
public void setValue(int i){ / code / }
// Other methods…
}

The method setValue assigns the value of i to the instance field value. What could you write for the implementation of setValue?

(a) value = i; (b) this.value = i; (c) value == i;
(d) Both (A) and (B) and above (e) (A), (B) and (C) above.

48) Which of the following is TRUE?

(a) In java, an instance field declared public generates a compilation error.
(b) int is the name of a class available in the package java.lang
(c) Instance variable names may only contain letters and digits.
(d) A class has always a constructor (possibly automatically supplied by the java compiler).
(e) The more comments in a program, the faster the program runs.

49) A constructor

(a) Must have the same name as the class it is declared within.
(b) Is used to create objects.
(c) May be declared private
(d) Both (A) and (B) above
(e) (a), (b) and (c) above.

50) Consider,

public class MyClass
{
public MyClass(){/code/}
// more code…
}

To instantiate MyClass, you would write?

(a) MyClass mc = new MyClass();
(b) MyClass mc = MyClass();
(c) MyClass mc = MyClass;
(d) MyClass mc = new MyClass;
(e) The constructor of MyClass should be defined as, public void MyClass(){/code/}.

 

Answers

1.00

2.compile error

3.compile error

4.compile error

5.Base dervied dervied

6.compile error

7.x=4 y=2

8.x=5

9.20

10.The output is true and MyStuff does NOT fulfill the Object.equals() contract

11.4

12.writing book

13.a b c

14.10

200

400


15.false, true, false


16.Run Time Exception


17.compile error

18.compile error

19.compile error

20.compile error

21.b

22.a

23.compile error

24.compile error

25.12345

26.java

java programming

27.java programming java programming

28.abcde

29.v

30.java

31.Equal Case 1

Equal Case 2

32.same

33.start same

34.11 -11

35.Programming

Prog

36.Free For Javatraining 

37.60, 30, 0, 20, 0

38.i=2

39.1 1

40.a=5 s=BLUE

41.A) d

42.A) c

43.A) d

44.A) c

45.A) d

46.A) e

47.A) d

48)A) d

49)A) e

50)A) a



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