Java source file header

Extension of compilation unit

We cannot differentiate between class and interface

The class or interface name should be postfixed with unit type

KeyListener()

addKistener()

addKeyListener()

eventKeyboardListener()

addMouse()

addMouseListener()

addMouseMotionListener()

eventMouseMotionListener()

A listener is a variable that is notified when an event occurs

A listener is an object that is notified when an event occurs

A listener is a method that is notified when an event occurs

None of these

getId()

getSource()

getEvent()

getEventObject()

EventObject

EventClass

ActionEvent

ItemEvent

String class

Object class

Abstract class

Array List class

abstract

extends

abstract and extends

None of the mentioned

Public

Private

Protected

Transient

Box obj = new Box();

Box obj = new Box;

obj = new Box();

new Box obj;

Public method is accessible to all other classes in the hierarchy

Public method is accessible only to subclasses of its parent class

Public method can only be called by object of its class

Public method can be accessed by calling object of the public class

upper

super

this

none of these

Aggregation

Composition

Encapsulation

Association

Every class must contain a main() method

Applets do not require a main() method at all

There can be only one main() method in a program

main() method must be made public

Method overriding

Method overloading

Method doubling

None of the mentioned

Private constructor ensures only one instance of a class exists at any point of time

Private constructor ensures multiple instances of a class exist at any point of time

Private constructor eases the instantiation of a class

Private constructor allows creating objects in other classes

Constructors can be synchronized in Java

Java does not provide default copy constructor

More than one constructor can be defined for one class

“this” and “super” keywords can be used in a constructor

Class.getInstance calls the constructor

Class.getInstance is same as new operator

Class.getInstance needs to have matching constructor

Class.getInstance creates object if class does not have any constructor

Protected constructor can be called directly

Protected constructor can only be called using super()

Protected constructor can be used outside package

Protected constructor can be instantiated even if child is in a different package

Compilation error

Compilation succeeds

Runtime error

Compilation succeeds but at the time of creating object using default constructor, it throws compilation error

Public members of class can be accessed by any code in the program

Private members of class can only be accessed by other members of the same class

Private members of a class can be inherited by a subclass.

Protected members of a class can be inherited by a subclass.

public

private

protected

None of these

final

last

constant

static

Static methods can call other static methods only

Static methods must only access static data

Static methods cannot refer to this or super in any way

When object of class is declared, each object contains its own copy of static variables

Variables declared as final can be initialized anytime.

Final variables must be initialized at the time of declaration

Arrays in java are implemented as objects.

All arrays in java contain an attribute-length which contains the number of elements stored in the array

Two or more methods with same name can be differentiated on the basis of their parameters data type

Two or more methods having same name can be differentiated on basis of number of parameters

Any already defined method in java’s library can be defined again in the program with different data type of parameters

If a method is returning a value, the calling statement must have a variable to store that value