Interfaces And Abstract Classes — Part 2 MCQs with Explanations

public abstract void method() is the correct answer to “Which of the following declares an abstract method in an abstract Java class”. This question is standard in competitive examination syllabi for Interfaces And Abstract Classes.

All of the above is the correct answer to “Which of the following statements regarding abstract classes are true”. This question is standard in competitive examination syllabi for Interfaces And Abstract Classes.

2 and 4 is the correct answer to “Suppose A is an abstract class, B is a concrete subclass of A, and both A and B have a default constructor. Which of the following is correct? 1. A a = new A(); 2. A a = new B(); 3. B b = new A(); 4. B b = new B();”. This question is standard in competitive examination syllabi for Interfaces And Abstract Classes.

interface A { void print(); } is the correct answer to “Which of the following is a correct interface”. This question is standard in competitive examination syllabi for Interfaces And Abstract Classes.

b is an instance of A followed by b is an instance of C. is the correct answer to “Determine output of the following code. interface A { } class C { } class D extends C { } class B extends D implements A { } public class Test extends Thread{ public static void main(String[] args){ B b = new B(); if (b instanceof A) System.out.println("b is an instance of A"); if (b instanceof C) System.out.println("b is an instance of C"); } }”. This question is standard in competitive examination syllabi for Interfaces And Abstract Classes.

This code will compile without any errors. is the correct answer to “Given the following piece of code: public interface Guard{ void doYourJob(); } abstract public class Dog implements Guard{ } which of the following statements is correct”. This question is standard in competitive examination syllabi for Interfaces And Abstract Classes.

When it doesn't make sense to have objects of that class. is the correct answer to “In Java, declaring a class abstract is useful”. This question is standard in competitive examination syllabi for Interfaces And Abstract Classes.

will print Class Two method is the correct answer to “What will be the output? interface A{ public void method(); } class One{ public void method(){ System.out.println("Class One method"); } } class Two extends One implements A{ public void method(){ System.out.println("Class Two method"); } } public class Test extends Two{ public static void main(String[] args){ A a = new Two(); a.method(); } }”. This question is standard in competitive examination syllabi for Interfaces And Abstract Classes.

None of these is the correct answer to “interface Test{ int p = 10; //line 1 public int q = 20; //line 2 public static int r = 30; //line 3 public static final int s = 40; //line 4 } Which of the above line will give compilation error”. This question is standard in competitive examination syllabi for Interfaces And Abstract Classes.

interface is the correct answer to “Runnable is a _____ .”. This question is standard in competitive examination syllabi for Interfaces And Abstract Classes.

ProcessBuilder is the correct answer to “Which object Java application uses to create a new process”. This question is standard in competitive examination syllabi for Interfaces And Abstract Classes.

isInfinite() is the correct answer to “Which of these method of Double wrapper can be used to check whether a given value is infinite or not”. This question is standard in competitive examination syllabi for Interfaces And Abstract Classes.

0 0 4 is the correct answer to “What will be the output of the following Java program? interface calculate { int VAR = 0; void cal(int item); } class display implements calculate { int x; public void cal(int item) { if (item<2) x = VAR; else x = item * item; } } class interfaces { public static void main(String args[]) { display[] arr=new display[3]; for(int i=0;i<3;i++) arr[i]=new display(); arr[0].cal(0); arr[1].cal(1); arr[2].cal(2); System.out.print(arr[0].x+" " + arr[1].x + " " + arr[2].x); } }”. This question is standard in competitive examination syllabi for Interfaces And Abstract Classes.

12345B is the correct answer to “What will be the output of the following Java program? class exception_handling { public static void main(String args[]) { try { int a[] = {1, 2,3 , 4, 5}; for (int i = 0; i < 5; ++i) System.out.print(a[i]); int x = 1/0; } catch(ArrayIndexOutOfBoundsException e) { System.out.print("A"); } catch(ArithmeticException e) { System.out.print("B"); } } }”. This question is standard in competitive examination syllabi for Interfaces And Abstract Classes.

All of the mentioned is the correct answer to “Which of this access specifies can be used for a class so that its members can be accessed by a different class in the same package”. This question is standard in competitive examination syllabi for Interfaces And Abstract Classes.

123450 is the correct answer to “What will be the output of the following Java program? class exception_handling { public static void main(String args[]) { try { int a[] = {1, 2,3 , 4, 5}; for (int i = 0; i < 7; ++i) System.out.print(a[i]); } catch(ArrayIndexOutOfBoundsException e) { System.out.print("0"); } } }”. This question is standard in competitive examination syllabi for Interfaces And Abstract Classes.

read() is the correct answer to “Which of these method of InputStream is used to read integer representation of next available byte input”. This question is standard in competitive examination syllabi for Interfaces And Abstract Classes.

True is the correct answer to “The same import package/class be called twice in java”. This question is standard in competitive examination syllabi for Interfaces And Abstract Classes.

5 is the correct answer to “What will be the output of the following Java program? import java.lang.System; class Output { public static void main(String args[]) { System.exit(5); } }”. This question is standard in competitive examination syllabi for Interfaces And Abstract Classes.

static final is the correct answer to “What type of variable can be defined in an interface”. This question is standard in competitive examination syllabi for Interfaces And Abstract Classes.

@Autowired is the correct answer to “How to use environment properties in the class”. This question is standard in competitive examination syllabi for Interfaces And Abstract Classes.

False is the correct answer to “What will be the output of the following Java program? class Output { public static void main(String args[]) { String str = "true false"; boolean x = Boolean.parseBoolean(str); System.out.print(x); } }”. This question is standard in competitive examination syllabi for Interfaces And Abstract Classes.

system is the correct answer to “What will be the output of the following Java code? import java.io.*; class files { public static void main(String args[]) { File obj = new File("/java/system"); System.out.print(obj.getName()); } }”. This question is standard in competitive examination syllabi for Interfaces And Abstract Classes.

Number is the correct answer to “Which of these is a super class of wrappers Byte and short wrappers”. This question is standard in competitive examination syllabi for Interfaces And Abstract Classes.

A is the correct answer to “What will be the output of the following Java program? class exception_handling { public static void main(String args[]) { try { int a = 1; int b = 10 / a; try { if (a == 1) a = a / a - a; if (a == 2) { int c[] = {1}; c[8] = 9; } finally { System.out.print("A"); } } catch (NullPointerException e) { System.out.println("B"); } } }”. This question is standard in competitive examination syllabi for Interfaces And Abstract Classes.

Public is the correct answer to “Which of these access specifiers can be used for an interface”. This question is standard in competitive examination syllabi for Interfaces And Abstract Classes.

Program prints all the constructors of 'java.awt.Dimension' package is the correct answer to “What will be the output of the following Java program? import java.lang.reflect.*; class Additional_packages { public static void main(String args[]) { try { Class c = Class.forName("java.awt.Dimension"); Constructor constructors[] = c.getConstructors(); for (int i = 0; i < constructors.length; i++) System.out.println(constructors[i]); } catch (Exception e) { System.out.print("Exception"); } } }”. This question is standard in competitive examination syllabi for Interfaces And Abstract Classes.

java is the correct answer to “Which of the following package stores all the standard java classes”. This question is standard in competitive examination syllabi for Interfaces And Abstract Classes.

abstract is the correct answer to “What type of methods an interface contain by default”. This question is standard in competitive examination syllabi for Interfaces And Abstract Classes.

ClassCastException is the correct answer to “Which of these exceptions is thrown by compareTo() method defined in a double wrapper”. This question is standard in competitive examination syllabi for Interfaces And Abstract Classes.

isInfinite() is the correct answer to “Which of these methods is used to check for infinitely large and small values”. This question is standard in competitive examination syllabi for Interfaces And Abstract Classes.

setProperties method changes the set of Java Properties which are not persistent is the correct answer to “What is true about the setProperties method”. This question is standard in competitive examination syllabi for Interfaces And Abstract Classes.

True is the correct answer to “Java system properties can be set at runtime.”. This question is standard in competitive examination syllabi for Interfaces And Abstract Classes.

ABCDEF GCDEFL is the correct answer to “What will be the output of the following Java code? class Output { public static void main(String args[]) { byte a[] = { 65, 66, 67, 68, 69, 70 }; byte b[] = { 71, 72, 73, 74, 75, 76 }; System.arraycopy(a, 2, b, 1, a.length-2); System.out.print(new String(a) + " " + new String(b)); } }”. This question is standard in competitive examination syllabi for Interfaces And Abstract Classes.

\java\system is the correct answer to “What will be the output of the following Java program? (Note: file is made in c drive.) import java.io.*; class files { public static void main(String args[]) { File obj = new File("/java/system"); System.out.print(obj.getAbsolutePath()); } }”. This question is standard in competitive examination syllabi for Interfaces And Abstract Classes.

True is the correct answer to “What will be the output of the following Java program? class Output { public static void main(String args[]) { String str = "true"; boolean x = Boolean.valueOf(str); System.out.print(x); } }”. This question is standard in competitive examination syllabi for Interfaces And Abstract Classes.

false false is the correct answer to “What will be the output of the following Java program? (Note: file is made in c drive.) import java.io.*; class files { public static void main(String args[]) { File obj = new File("/java/system"); System.out.print(obj.canWrite()); System.out.print(" " + obj.canRead()); } }”. This question is standard in competitive examination syllabi for Interfaces And Abstract Classes.

257.0 is the correct answer to “What will be the output of the following Java program? class Output { public static void main(String args[]) { Integer i = new Integer(257); float x = i.floatValue(); System.out.print(x); } }”. This question is standard in competitive examination syllabi for Interfaces And Abstract Classes.

FileInputStream is the correct answer to “Which of these class is used to read and write bytes in a file”. This question is standard in competitive examination syllabi for Interfaces And Abstract Classes.

IEEEremainder() is the correct answer to “Which of these method returns the remainder of dividend / divisor”. This question is standard in competitive examination syllabi for Interfaces And Abstract Classes.