Introduction to Classes and Methods

1) Which is used to get the value of the instance variables?
Ans: Dot notation.

2) The new operator creates a single instance named class and returns a
reference to that object.
a)True
b)False
Ans: a.

3) A class is a template for multiple objects with similar features.
a)True
b)False
Ans: a.

4) What is mean by garbage collection?
Ans: When an object is no longer referred to by any variable, Java automatically
reclaims memory used by that object. This is known as garbage collection.

5) What are methods and how are they defined?
Ans: Methods are functions that operate on instances of classes in which they are defined.Objects can communicate with each other using methods and can call methods in other classes.
Method definition has four parts. They are name of the method, type of object or primitive type the method returns, a list of parameters and the body of the method.
A method's signature is a combination of the first three parts mentioned above.

6) What is calling method?
Ans: Calling methods are similar to calling or referring to an instance variable. These methods are accessed using dot notation.
Ex: obj.methodname(param1,param2)

7) Which method is used to determine the class of an object?
Ans: getClass( ) method can be used to find out what class the belongs to. This class is defined in the object class and is available to all objects.

8) All the classes in java.lang package are automatically imported when
a program is compiled.
a)True
b)False
Ans: a.

9) How can class be imported to a program?
Ans: To import a class, the import keyword should be used as shown.;
import classname;

10) How can class be imported from a package to a program?
Ans: import java . packagename . classname (or) import java.package name.*;

11) What is a constructor?
Ans: A constructor is a special kind of method that determines how an object is
initialized when created.


12) Which keyword is used to create an instance of a class?
Ans: new.

13) Which method is used to garbage collect an object?
Ans: finalize ().

14) Constructors can be overloaded like regular methods.
a)True
b)False
Ans: a.

15) What is casting?
Ans: Casting is bused to convert the value of one type to another.

16) Casting between primitive types allows conversion of one primitive type to another.
a)True
b)False
Ans: a.

17) Casting occurs commonly between numeric types.
a)True
b)False
Ans: a.

18) Boolean values can be cast into any other primitive type.
a)True
b)False
Ans: b.

19) Casting does not affect the original object or value.
a)True
b)False
Ans: a.

20) Which cast must be used to convert a larger value into a smaller one?
Ans: Explicit cast.

21) Which cast must be used to cast an object to another class?
Ans: Specific cast.

22) Which of the following features are common to both Java & C++?
A.The class declaration
b.The access modifiers
c.The encapsulation of data & methods with in objects
d.The use of pointers
Ans: a,b,c.

23) Which of the following statements accurately describe the use of access modifiers within a class definition?
a.They can be applied to both data & methods
b.They must precede a class's data variables or methods
c.They can follow a class's data variables or methods
d.They can appear in any order
e.They must be applied to data variables first and then to methods
Ans: a,b,d.
24) Suppose a given instance variable has been declared private.
Can this instance variable be manipulated by methods out side its class?
a.yes
b.no
Ans: b.

25) Which of the following statements can be used to describe a public method?
a.It is accessible to all other classes in the hierarchy
b.It is accessablde only to subclasses of its parent class
c.It represents the public interface of its class
d.The only way to gain access to this method is by calling one of the public class
methods
Ans: a,c.

26) Which of the following types of class members can be part of the internal part of a class?
a.Public instance variables
b.Private instance variables
c.Public methods
d.Private methods
Ans: b,d.

27) You would use the ____ operator to create a single instance of a named class.
a.new
b.dot
Ans: a.

28) Which of the following statements correctly describes the relation between an object and the instance variable it stores?
a.Each new object has its own distinctive set of instance variables
b.Each object has a copy of the instance variables of its class
c.the instance variable of each object are seperate from the variables of other objects
d.The instance variables of each object are stored together with the variables of other objects
Ans: a,b,c.

29) If no input parameters are specified in a method declaration then the declaration will include __.
a.an empty set of parantheses
b.the term void
Ans: a.