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Java Objective Questions (MCQs) - 225

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Question: 161

Find the output of below program

import java.util.*; 

public class Main
{
	public static void main(String[] args) {
	    List<Integer> mylist = new ArrayList();
	    System.out.println(mylist.add(5));
	}
}

(A) Nothing is printed
(B) 5
(C) 0
(D) true

Level: Practitioner Category: collection
[Posted by: Admin | Chicago, USA]

Question: 162

import java.util.*; 

public class Main
{
	public static void main(String[] args) {
	    List<Integer> mylist = new ArrayList();
	    mylist.add(-2);
	    mylist.add(-1);
	    mylist.add(0);
	    int a = mylist.get(-1);
	    System.out.println(a);
	}
}

(A) -1
(B) 0
(C) IndexOutOfBoundsException
(D) None of the above

Level: Practitioner Category: collection
[Posted by: Admin | Chicago, USA]

Question: 163

Find the output of below program

import java.util.*; 

public class Main
{
	public static void main(String[] args) {
	    List<Integer> mylist = new ArrayList();
	    mylist.add(-2);
	    mylist.add(-1);
	    mylist.add(0);
	    System.out.println(mylist.get((mylist.remove(2))));
	}
}

(A) true
(B) -2
(C) Compilation Error
(D) 0

Level: Practitioner Category: collection
[Posted by: Admin | Chicago, USA]

Question: 164

Find the output of below program

import java.util.*; 

public class Main
{
	public static void main(String[] args) {
	    List<Integer> mylist = new ArrayList();
	    mylist.add(-2);
	    mylist.add(-1);
	    mylist.add(0);
	    
	    System.out.print(mylist.size());
	    for(int i = 0; i<mylist.size(); i++){
	        mylist.remove(i);
	        System.out.print(mylist.size());
	    }
	    
	}
}

(A) 331
(B) 3321
(C) 310
(D) 321

Level: Practitioner Category: collection
[Posted by: Admin | Chicago, USA]

Question: 165

List is part of Java Collections API

(A) True
(B) False

Level: Beginner Category: collection
[Posted by: Admin | Chicago, USA]

Question: 166

Find the output of below program

import java.util.*;

public class Main
{
public static void main(String[] args) {
    List<Integer> list = new ArrayList();
    list.add(10);
    System.out.print(list.size());
    List<Integer> list2 = new ArrayList(list);
    System.out.print(list2.size());

    }
}

(A) 22
(B) 12
(C) 11
(D) 21

Level: Beginner Category: collection
[Posted by: Admin | Chicago, USA]

Question: 167

Java List has an instance variable to handle the size.
It is incremented when you add, and decremented when you remove. Calling list.size() returns a variable, and is therefore O(1)

(A) True
(B) False

Level: Practitioner Category: collection
[Posted by: Admin | Chicago, USA]

Question: 168

What is Big-O complexity notation to search an element in List

(A) O(1)
(B) O(n)
(C) O(log(n))
(D) None of these

Level: Expert Category: collection
[Posted by: Admin | Chicago, USA]

Question: 169

What is Big-O complexity notation to insert an element in List

(A) O(n)
(B) O(1)
(C) O(log(n))
(D) None of these

Level: Expert Category: collection
[Posted by: Admin | Chicago, USA]

Question: 170

How many instances Singleton class can have in Java?

(A) 1
(B) Depends on the calling program
(C) Depends on class creating object of Singleton class
(D) 256

Level: Practitioner Category: singleton
[Posted by: Admin | Chicago, USA]

Question: 171

Packages can contain hidden classes that are used by the package itself but are not visible or accessible outside the package.

(A) True
(B) False

Level: Beginner Category: packages
[Posted by: Admin | Chicago, USA]

Question: 172

Different packages can have classes with the same name

(A) True
(B) False

Level: Beginner Category: packages
[Posted by: Admin | Chicago, USA]

Question: 173

Packages resolves ambiguity for classes which have the same name

(A) True
(B) False

Level: Beginner Category: packages
[Posted by: Admin | Chicago, USA]

Question: 174

Does Java allows default values to arguments?

public void sum(int a = 10, int b = 20) ?

(A) Yes
(B) No

Level: Beginner Category: overriding
[Posted by: Admin | Chicago, USA]

Question: 175

import java.util.*;

public class Main
{
    public static float sum1(float a, float b){
        System.out.print("cppbuzz");
        return a+b;
    }
    
    public static float sum(int a, int b){
        System.out.print("hello");
        return a+b;
    }
    
   public static void main(String[] args) {
        System.out.println(sum(-5, -6));
   }
}

(A) cppbuzz-11
(B) cppbuzz-11.0
(C) hello-11
(D) hello-11.0

Level: Practitioner Category: overriding
[Posted by: Admin | Chicago, USA]

Question: 176

Which collection framework allows null values and is unsynchronized?

(A) HashTable
(B) EnumSet
(C) Vector
(D) ArrayList

Level: Expert Category: collection
[Posted by: Admin | Chicago, USA]

Question: 177

Converting an object of type (Integer) to its corresponding primitive (int) value is known as

(A) Autoboxing
(B) Morphing
(C) Unboxing
(D) Typecasting

Level: Expert Category: other
[Posted by: Admin | Chicago, USA]

Question: 178

Find the output of below program

class A {
  void f1 () {
    System.out.print("class-A ");
  }
}
class B extends A {
  void f1 () {
    System.out.print("Class-B ");
  }
} 
 
class Main {
  public static void main (String s[]) {
    A refA = new A();
    A refB = new B();
 
    refA.f1();
    refB.f1();
  }
}

(A) class-A class-A
(B) class-B class-B
(C) class-B class-A
(D) class-A class-B

Level: Practitioner Category: polymorphism
[Posted by: Admin | Chicago, USA]

Question: 179

Which of the following is a correct implementation of method overloading?

(A) void methodA(){} int methodA(){}
(B) void methodA(){} void methodA(int a){}
(C) void methodA(){} int methodB(int a){}
(D) int methodA(){} int methodAA(i{}

Level: Practitioner Category: polymorphism
[Posted by: Admin | Chicago, USA]

Question: 180

static import provides accessibility to static members of the class only. State true or false

(A) True
(B) False

Level: Practitioner Category: packages
[Posted by: Admin | Chicago, USA]

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Java Objective Questions (MCQs) - 225

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