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Java - Test Questions on 'Abs' - 25 questions found


Which of the following is not true for abstract classes ?Core Java
Abstract Class is only meant to be sub classed and not supposed to be instantiated.
Abstract class handlers can be used to handle derived class objects.
We can't have an abstract class without abstract methods.
Abstract class has member elements.

  abstract class  abstract methods

Which of the following can be declared abstract ?Core Java
static methods
instance methods
static variable
instance variables

  abstract

Which of the following is false about main method ?Core Java
It should be declared public and static
it should have only 1 argument of type String array
We can override main method
We can overload main method

  java  main method

Which of the following class creates mutable objects ?Core Java
Boolean
File
String
StringBuffer

  java  immutable

Which of the following is wrong for final instance variables ?Core Java
They cannot be changed after initialization
They can be initialized directly within static method
They can be declared and initialized together at the same place
They can be initialized within constructor

  java  final  final variable  java keywords

Which of the following is false for final ?Core Java
Final methods cannot be overriden
Final methods cannot be overloaded
Final classes cannot be subclassed
Final class cannot be abstract

  java  final  java keyword

Which of the following statement is not true ?Core Java
x==y means they are pointing to the same object
x==y means that they hold same information
x.equals(y) means they are pointing to the same object
x.equals(y) means that they hold same information

  

When String literals are compared using ==, they always returns true if the string values are same because .. Core Java
of overridden compareTo method
of overridden compare method
of String Pool
== means that the object contents are equal

  

Which of the following has been introduced with Java 8 ?Core Java
StringBuffer
StringBuilder
StringFilter
StringJoiner

  java  java8  java 8  String  StringJoiner

Which of the following Java feature promotes access protection or Hiding ?Core Java
Inheritance
Encapsulation
Abstraction
Composition

  java  java concepts  java features  oops concepts  oops features  access protection  information hiding

Which of the following Java feature promotes Code Re usability ?Core Java
Abstraction
Encapsulation
Inheritance
Polymorphism

  java  java concepts  java features  code reusability

In case of String Literals ..Core Java
x==y on all literals always returns false
x.equals(y) on all literals always returns false
if x.equals(y) returns true, x==y returns true too
if x.equals(y) returns false, x==y returns true

  

What will be the output of following ?

String str1 = new String("String1");
String str2 = new String("String1");
System.out.print(str1 == str2);
System.out.print(str1.equals(str2));
str1 = str2;
System.out.print(str1 == str2);
Core Java
falsetruetrue
truetruetrue
truetruefalse
falsetruefalse

  equals  object equality

What will be the output of following code ?

String str1 = "String1";
String str2 = "String1";
System.out.print(str1 == str2);
System.out.print(str1.equals(str2));
str1 = str2;
System.out.print(str1 == str2);
Core Java
falsetruetrue
falsefalsetrue
truetruetrue
falsefalsefalse

  equals  object equality  string pool

What will be the output of following code ?

String str1 = "String1";
String str2 = "String2";
str1.concat("String3");
System.out.print(str1);
System.out.print(str2);
Core Java
String1String2
String1String3String3
String1String3String1String3
String1String1

  

What will be the output of following code ?

String str1 = "String1";
String str2 = "String2";
str1=str1.concat("String3");
System.out.print(str1);
System.out.print(str2);
Core Java
String1String2
String1String3String2
String1String2String3
String1Stringg3String1

  

If X implements Y and Y extends Z, Which of the following initialization is correct ?Core Java
X x = new Y();
X x = new Z();
Z z = new Y();
Z z = new X();

  interfaces

If class A implements X interface, and Class B implements Y interface, and X is the parent of Y, Which of the following initialization is correct ?Core Java
A a = new B();
Y y = new A();
X x = new B();
Y y = new A();

  interfaces   inheritance

What will be the output of exceuting main method ?

public static void main(String[] args){
      List list = new ArrayList();
      list.add(1);
      list.add(2);
      list.add(3);
      System.out.println(list);
   }
Core Java
1,2,3
Order cannot be determined
compilation error
3,2,1

  collections  list  arraylist

Which of the following class creates immutable objects ?Core Java
String
StringBuffer
StringBuilder
None of these create immutable objects.

  String  StringBuffer  StringBuilder  Immutable

Which of the following class is synchronized ?Core Java
String
StringBuffer
StringBuilder
None of these

  String  StringBuffer  StringBuilder  Synchronized

Binary Search requires that the collection should beAlgorithm
Sorted in Ascending Order
Sorted in Descending Order
Sorted in any Order
Unsorted

  Binary Search  Search  Algorithm

Which of the following methods are used by Java Garbage Collection Mechanism ?Core Java
final
finally
finalize
All of the above

  garbage collection  finalize

Which of the following can be overridden ?Core Java
final instance methods
final static methods
non final instance methods
non final static methods

  overriding

In which case finally won't get executed ?Core Java
in case of exception
in case of normal execution
in case of return statement before end of try block
in case of force program termination

  finally







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