Java Programming Practice MCQs Codetantra. CBT-3
01. Predict the correct output:
import java.io.*; class Main { public static void main(String[] args) { Integer a = new Integer(418); int b = a; System.out.println(a); System.out.println(b); Character c = '4'; char d = c; System.out.println(c); System.out.println(d); } }
02. If code executes fine then predict the correct output otherwise choose the suitable option.
class Code { int a; } public class Main { public static void main(String[] args) { Code c = new Code(); c.a = 24; Code d = new Code(); d.a = 7; Compute(c, d); System.out.println(c.a + " " + d.a); } public static void Compute(Code c, Code d) { c.a = c.a + d.a; d.a = c.a * d.a; int temp = c.a; c.a = d.a; d.a = temp; } }
03.
What are the contents array after the following code has been executed? int[][] array = {{5,8,3},{2,7,5}}; int value = 0; for (int row = 1; row < array.length; row++) { for (int col = 1; col < array[0].length; col++) { if (array[row][col] % 2 == 1) { array[row][col] = array[row][col] + 1; } else if (array[row][col] % 2 == 0) { array[row][col] = array[row][col] * 2; } } }
04. If code executes fine then predict the correct output otherwise choose the suitable option.
class Code { int a; } public class Main { public static void main(String[] args) { Code c = new Code(); c.a = 14; Code d = new Code(); d.a = 45; Compute(c, d); System.out.println(c.a + " " + d.a); } public static void Compute(Code c, Code d) { c.a = c.a + d.a; d.a = c.a * d.a; int temp = c.a; c.a = d.a; d.a = c.a; c.a = temp; } }
05 What will be the correct output of below given code?
class MainSubClass { void f(int i) { System.out.print(i); } } public class Main extends MainSubClass { void f(int i) { System.out.print(10*i); } public static void main(String[] args) { MainSubClass x = new Main(); Main y = new Main(); Main z = new Main(); x.f(31); ((MainSubClass)y).f(63); z.f(190); } }
07. If code executes fine then predict the correct output otherwise choose the suitable option.
class Code { final public void showTime() { System.out.println("885"); } } class Tantra extends Code { public void showTime() { System.out.println("-460"); } } public class Main { public static void main(String[] args) { Code b = new Tantra(); b.showTime(); } }
08. Predict the correct results of below given code snippet:
abstract class CT { public int x; CT() { x = 6; } abstract public void showTime(); abstract final public void funTime(); } class Main extends CT { public void showTime(int a) { this.x = a; } final public void funTime() { System.out.println(x); } public static void main(String[] args) { Main object = new Main(); object.showTime(169); object.funTime(); } }
09. Predict the correct results of the code snippet given below:
class D { static int x; protected static void getMethod() { System.out.println("9"); ++x; } } public class Main extends D { protected static void getMethod() { System.out.println("20"); ++x; } public static void main(String[] args) { D object = new D(); object.getMethod(); System.out.print(x); } }
10.What is the output of the following code
public class Main { public static void main(String[] args) { int[][] matrix = {{2, 9, 13, 16}, {24, 28, 31, 39}, {5, 3, 2, 1}, {1, 9, 9, 8}}; for (int i = 0; i < 4; i++) System.out.print(matrix[1][i] + " "); } }
11. Decode the code and choose the correct results:
abstract class A { final void showTime() { System.out.println("4323"); } } class B extends A { static void funTime() { System.out.println("6896"); } } public class Main { public static void main(String args[]) { A object = new B(); object.showTime(); B.funTime(); } }
12. What is the output of the following
class Atom { Atom() { System.out.print("7 "); } } class Rock extends Atom { Rock(String type) { System.out.print(type); } } public class Mountain extends Rock { Mountain() { super("14 "); new Rock("14 "); } public static void main(String[] a) { new Mountain(); } }
13. Predict the correct results of below given code snippet:
import java.io.*; interface a { static int x = 36; default void showTime2() { System.out.println("68"); x++; } } class Main implements a { public void showTime1() { System.out.println("19"); x++; } public static void main(String[] args) { Main test = new Main(); test.showTime1(); System.out.println(x); test.showTime2(); System.out.println(x); } }
14. Predict the correct results of below given code snippet:
import java.io.*; interface a { final int x = 32; default void showTime2() { System.out.println("65"); } } class Main implements a { public void showTime1() { System.out.println("15"); } public static void main(String[] args) { Main test = new Main(); test.showTime1(); System.out.println(x); test.showTime2(); System.out.println(x); } }
15. What is the output of the following code
class A { public int i; protected int j; } class B extends A { int j; void display() { super.j = 1; System.out.println(i + " " + j); } } class Output { public static void main(String args[]) { B obj = new B(); obj.i = 9; obj.j = 15; obj.display(); } }
16. Predict the correct results of below given code snippet:
import java.io.*; interface a { final int x = 114; void showTime(); } class Main implements a { public void showTime() { System.out.println("31"); } public static void main(String[] args) { Main test = new Main(); test.showTime(); System.out.println(x); } }
17. Predict the correct results of below given code snippet:
abstract class B { B() { System.out.println("42"); } static void funTime1() { System.out.println("188"); } } class D extends B { D() { System.out.println("124"); } static void funTime2() { System.out.println("57"); } } class Main { public static void main(String args[]) { D object = new D(); D.funTime2(); B.funTime1(); } }
18. If code executes fine then predict the correct output otherwise choose the suitable option.
class Code { public void showTime() { System.out.println("1016"); } } class Tantra extends Code { public void showTime() { System.out.println("-197"); } } public class Main { public static void main(String[] args) { Code b = new Tantra(); b.showTime(); } }
19. What is the output of the following code?
class A { int i; } class B extends A { int j; void show() { super.i = j + 1; System.out.println(j + " " + i); } } class Inheritance { public static void main(String args[]) { B obj = new B(); obj.i = 6; obj.j = 3; obj.show(); } }
20. Predict the correct results of below given code snippet:
abstract class B { abstract void funTime(); } class D extends B { static void funTime() { System.out.println("9"); } } class Main { public static void main(String args[]) { B object = new D(); object.funTime(); } }
21. Find out the correct results of below given code snippet:
public class Main { void process() { String a = "82"; String b = subProcess(a); System.out.print(" "+a + " " + b); } String subProcess(String a) { a = a + " 128"; System.out.print(a); return "292"; } public static void main(String[] args) { Main obj = new Main(); obj.process(); } }
22. Predict the correct results of below given code snippet:
abstract class B { B() { System.out.println("7"); } void funTime() { System.out.println("72"); } } class D extends B { D() { System.out.println("139"); } } class Main { public static void main(String args[]) { D object = new D(); object.funTime(); } }
23. Predict the right output:
import java.io.*; import java.util.*; class Main { public static void main (String[] args) { String s= "03469"; System.out.println(s.length()); System.out.println(s.charAt(0)); String s1 = "034"; String s2 = "69"; System.out.println(s1.concat(s2)); String s4 = "14 21 37"; System.out.println(s4.indexOf("20")); } }
24. What is the output of the following code?
class A { int i; void show() { System.out.println(i); } } class B extends A { int j; void show() { System.out.println(j); } } class inheritanceDemo { public static void main(String args[]){ B obj = new B(); obj.i = 1; obj.j = 17; obj.show(); } }
25. Choose the correct output for the below given code snippet.
class CT { static int temp = 37; CT() { temp = 70; } } class Main { public static void main(String args[]) { CT t1 = new CT(); System.out.println(t1.temp*3); } }
26. Predict the correct results of below given code snippet:
abstract class B { abstract void funTime(); } class D extends B { final void funTime() { System.out.println("31"); } } class Main { public static void main(String args[]) { B object = new D(); object.funTime(); } }
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