- What is CAFEBABE?
- Without using Thread class and Runnable interface can we create Thread?
- what is Greey thread?
- what is starvation?
- What is deadlock?
- what is selifish thread?
- what is friendly thread?
- what is dynamic polymorphishism?
- what happens when an object is created?
- what is markable interface?
JAVA
kirran
Tuesday, August 7, 2012
Some Intresting questions in java
Friday, July 6, 2012
CORE JAVA INTERVIEW QUESTIONS AND ANSWERS
1. What is
the most important feature of Java?
Java is a platform independent
language.
2. What do
you mean by platform independence?
Platform independence means
that we can write and compile the java code in one platform (eg Windows) and
can execute the class in any other supported platform eg (Linux,Solaris,etc).
3. What is
a JVM?
JVM is Java Virtual Machine
which is a run time environment for the compiled java class files.
4. Are
JVM's platform independent?
JVM's are not platform
independent. JVM's are platform specific run time implementation provided by
the vendor.
5. What is
the difference between a JDK and a JVM?
JDK is Java Development Kit
which is for development purpose and it includes execution environment also.
But JVM is purely a run time environment and hence you will not be able to
compile your source files using a JVM.
6. What is
a pointer and does Java support pointers?
Pointer is a reference handle
to a memory location. Improper handling of pointers leads to memory leaks and
reliability issues hence Java doesn't support the usage of pointers.
7. What is the base class of all
classes?
java.lang.Object
8. Does
Java support multiple inheritance?
Java doesn't support multiple
inheritance.
9. Is Java
a pure object oriented language?
Java uses primitive data types
and hence is not a pure object oriented language.
10. Are
arrays primitive data types?
In Java, Arrays are objects.
11. What
is difference between Path and Classpath?
Path and Classpath are
operating system level environment variales. Path is used define where the
system can find the executables(.exe) files and classpath is used to specify
the location .class files.
12. What
are local variables?
Local
varaiables are those which are declared within a block of code like methods.
Local variables should be initialised before accessing them.
13. What
are instance variables?
Instance variables are those
which are defined at the class level. Instance variables need not be
initialized before using them as they are automatically initialized to their
default values.
14. How to
define a constant variable in Java?
The variable should be
declared as static and final. So only one copy of the variable
exists for all instances of the class and the value can't be changed also.
static final int PI = 2.14; is an example for constant.
static final int PI = 2.14; is an example for constant.
15. Should
a main() method be compulsorily declared in all java classes?
No not required. main()
method should be defined only if the source class is a java application.
16. What
is the return type of the main() method?
Main() method doesn't
return anything hence declared void.
17. Why is
the main() method declared static?
main() method is called
by the JVM even before the instantiation of the class hence it is declared as static.
18. What
is the arguement of main() method?
main() method accepts
an array of String object as arguement.
19. Can a
main() method be overloaded?
Yes. You can have any number
of main() methods with different method signature and implementation in
the class.
20. Can a
main() method be declared final?
Yes. Any inheriting class will
not be able to have it's own default main() method.
21. Does
the order of public and static declaration matter in main() method?
No. It doesn't matter but void
should always come before main().
22. Can a
source file contain more than one class declaration?
Yes a single source file can
contain any number of Class declarations but only one of the class can be
declared as public.
23. What
is a package?
Package is a collection of
related classes and interfaces. package declaration should be first statement
in a java class.
24. Which
package is imported by default?
java.lang package is
imported by default even without a package declaration.
25. Can a
class declared as private be accessed outside it's package?
Not possible.
26. Can a
class be declared as protected?
A class can't be declared as protected.
only methods can be declared as protected.
27. What
is the access scope of a protected method?
A protected method can
be accessed by the classes within the same package or by the subclasses of the
class in any package.
28. What
is the purpose of declaring a variable as final?
A final variable's
value can't be changed. final variables should be initialized before
using them.
29. What
is the impact of declaring a method as final?
A method declared as final
can't be overridden. A sub-class can't have the same method signature with a
different implementation.
30. I
don't want my class to be inherited by any other class. What should i do?
You should declared your class
as final. But you can't define your class as final, if it is an abstract
class. A class declared as final can't be extended by any other class.
31. Can
you give few examples of final classes defined in Java API?
java.lang.String,
java.lang.Math are final classes.
32. How is
final different from finally and finalize()?
final is a modifier
which can be applied to a class or a method or a variable. final class
can't be inherited, final method can't be overridden and final
variable can't be changed.
finally is an exception handling code section which gets executed whether an exception is raised or not by the try block code segment.
finalize() is a method of Object class which will be executed by the JVM just before garbage collecting object to give a final chance for resource releasing activity.
finally is an exception handling code section which gets executed whether an exception is raised or not by the try block code segment.
finalize() is a method of Object class which will be executed by the JVM just before garbage collecting object to give a final chance for resource releasing activity.
33. Can a
class be declared as static?
No a class cannot be defined
as static. Only a method, a variable or a block of code can be declared
as static.
34. When
will you define a method as static?
When a method needs to be
accessed even before the creation of the object of the class then we should
declare the method as static.
35. What
are the restriction imposed on a static method or a static block of code?
A static method should not
refer to instance variables without creating an instance and cannot use
"this" operator to refer the instance.
36. I want
to print "Hello" even before main() is executed. How will you acheive
that?
Print the statement inside a
static block of code. Static blocks get executed when the class gets loaded
into the memory and even before the creation of an object. Hence it will be
executed before the main() method. And it will be executed only once.
37. What
is the importance of static variable?
static variables are class
level variables where all objects of the class refer to the same variable. If
one object changes the value then the change gets reflected in all the objects.
38. Can we
declare a static variable inside a method?
Static varaibles are class
level variables and they can't be declared inside a method. If declared, the
class will not compile.
39. What
is an Abstract Class and what is it's purpose?
A Class which doesn't provide
complete implementation is defined as an abstract class. Abstract classes
enforce abstraction.
40. Can a
abstract class be declared final?
Not possible. An abstract
class without being inherited is of no use and hence will result in compile
time error.
41. What
is use of a abstract variable?
Variables can't be declared as
abstract. only classes and methods can be declared as abstract.
42. Can
you create an object of an abstract class?
Not possible. Abstract classes
can't be instantiated.
43. Can a
abstract class be defined without any abstract methods?
Yes it's possible. This is
basically to avoid instance creation of the class.
44. Class
C implements Interface I containing method m1 and m2 declarations. Class C has
provided implementation for method m2. Can i create an object of Class C?
No not possible. Class C
should provide implementation for all the methods in the Interface I.
Since Class C didn't provide implementation for m1 method, it has
to be declared as abstract. Abstract classes can't be instantiated.
45. Can a
method inside a Interface be declared as final?
No not possible. Doing so will
result in compilation error. public and abstract are the only
applicable modifiers for method declaration in an interface.
46. Can an
Interface implement another Interface?
Intefaces doesn't provide
implementation hence a interface cannot implement another interface.
47. Can an
Interface extend another Interface?
Yes an Interface can inherit
another Interface, for that matter an Interface can extend more than one
Interface.
48. Can a
Class extend more than one Class?
Not possible. A Class can
extend only one class but can implement any number of Interfaces.
49. Why is
an Interface be able to extend more than one Interface but a Class can't extend
more than one Class?
Basically Java doesn't allow
multiple inheritance, so a Class is restricted to extend only one Class. But an
Interface is a pure abstraction model and doesn't have inheritance hierarchy
like classes(do remember that the base class of all classes is Object). So an
Interface is allowed to extend more than one Interface.
50. Can an
Interface be final?
Not possible. Doing so so will
result in compilation error.
51. Can a
class be defined inside an Interface?
Yes it's possible.
52. Can an
Interface be defined inside a class?
Yes it's possible.
53. What
is a Marker Interface?
An Interface which doesn't
have any declaration inside but still enforces a mechanism.
54. Which
object oriented Concept is achieved by using overloading and overriding?
Polymorphism.
55.Why
does Java not support operator overloading?
Operator overloading makes the
code very difficult to read and maintain. To maintain code simplicity, Java
doesn't support operator overloading.
56. Can we
define private and protected modifiers for variables in interfaces?
No.
57. What
is Externalizable?
Externalizable is an Interface
that extends Serializable Interface. And sends data into Streams in Compressed
Format. It has two methods, writeExternal(ObjectOuput out) and readExternal(ObjectInput
in)
58. What modifiers
are allowed for methods in an Interface?
Only public and abstract
modifiers are allowed for methods in interfaces.
59. What
is a local, member and a class variable?
Variables declared within a
method are "local" variables.
Variables declared within the
class i.e not within any methods are "member" variables (global
variables).
Variables declared within the
class i.e not within any methods and are defined as "static" are
class variables.
60. What
is an abstract method?
An abstract method is a method
whose implementation is deferred to a subclass.
61. What
value does read() return when it has reached the end of a file?
The read() method
returns -1 when it has reached the end of a file.
62. Can a
Byte object be cast to a double value?
No, an object cannot be cast
to a primitive value.
63. What
is the difference between a static and a non-static inner class?
A non-static inner class may
have object instances that are associated with instances of the class's outer
class. A static inner class does not have any object instances.
64. What
is an object's lock and which object's have locks?
An object's lock is a
mechanism that is used by multiple threads to obtain synchronized access to the
object. A thread may execute a synchronized method of an object only after it
has acquired the object's lock. All objects and classes have locks. A class's
lock is acquired on the class's Class object.
65. What
is the % operator?
It is referred to as the
modulo or remainder operator. It returns the remainder of dividing the first
operand by the second operand.
66. When
can an object reference be cast to an interface reference?
An object reference be cast to
an interface reference when the object implements the referenced interface.
67. Which
class is extended by all other classes?
The Object class is extended
by all other classes.
68. Which
non-Unicode letter characters may be used as the first character of an
identifier?
The non-Unicode letter
characters $ and _ may appear as the first character of an
identifier
69. What restrictions
are placed on method overloading?
Two methods may not have the
same name and argument list but different return types.
70. What
is casting?
There are two types of
casting, casting between primitive numeric types and casting between object
references. Casting between numeric types is used to convert larger values,
such as double values, to smaller values, such as byte values. Casting between
object references is used to refer to an object by a compatible class,
interface, or array type reference.
71. What
is the return type of a program's main() method?
void.
72. If a
variable is declared as private, where may the variable be accessed?
A private variable may only be
accessed within the class in which it is declared.
73. What
do you understand by private, protected and public?
These are accessibility
modifiers. Private is the most restrictive, while public is the
least restrictive. There is no real difference between protected and the
default type (also known as package protected) within the context of the same
package, however the protected keyword allows visibility to a derived class in
a different package.
74. What
is Downcasting ?
Downcasting is the casting
from a general to a more specific type, i.e. casting down the hierarchy
75. What
modifiers may be used with an inner class that is a member of an outer class?
A (non-local) inner class may
be declared as public, protected, private, static, final, or abstract.
76. How
many bits are used to represent Unicode, ASCII, UTF-16, and UTF-8 characters?
Unicode requires 16 bits and
ASCII require 7 bits Although the ASCII character set uses only 7 bits, it is
usually represented as 8 bits.
UTF-8 represents characters
using 8, 16, and 18 bit patterns.
UTF-16 uses 16-bit and larger
bit patterns.
77. What
restrictions are placed on the location of a package statement within a source
code file?
A package statement must
appear as the first line in a source code file (excluding blank lines and
comments).
78. What
is a native method?
A native method is a method that
is implemented in a language other than Java.
79. What
are order of precedence and associativity, and how are they used?
Order of precedence determines
the order in which operators are evaluated in expressions. Associatity
determines whether an expression is evaluated left-to-right or right-to-left.
80. Can an
anonymous class be declared as implementing an interface and extending a class?
An anonymous class may
implement an interface or extend a superclass, but may not be declared to do
both.
81. What is
the range of the char type?
The range of the char
type is 0 to 216 - 1 (i.e. 0 to 65535.)
82. What
is the range of the short type?
The range of the short
type is -(215) to 215 - 1. (i.e. -32,768 to 32,767)
83. Why
isn't there operator overloading?
Because C++ has proven by
example that operator overloading makes code almost impossible to maintain.
84. What
does it mean that a method or field is "static"?
Static variables and methods
are instantiated only once per class. In other words they are class variables,
not instance variables. If you change the value of a static variable in a
particular object, the value of that variable changes for all instances of that
class. Static methods can be referenced with the name of the class rather than
the name of a particular object of the class (though that works too). That's
how library methods like System.out.println() work. out is a static
field in the java.lang.System class.
85. Is
null a keyword?
The null value is not a
keyword.
86. Which
characters may be used as the second character of an identifier, but not as the
first character of an identifier?
The digits 0 through 9 may not
be used as the first character of an identifier but they may be used after the
first character of an identifier.
87. Is the
ternary operator written x : y ? z or x ? y : z ?
It is written x ? y : z.
88. How is
rounding performed under integer division?
The fractional part of the
result is truncated. This is known as rounding toward zero.
89. If a
class is declared without any access modifiers, where may the class be
accessed?
A class that is declared
without any access modifiers is said to have package access. This means that
the class can only be accessed by other classes and interfaces that are defined
within the same package.
90. Does a
class inherit the constructors of its superclass?
A class does not inherit
constructors from any of its superclasses.
91. Name
the eight primitive Java types.
The eight primitive types are
byte, char, short, int, long, float, double, and boolean.
92. What
restrictions are placed on the values of each case of a switch statement?
During compilation, the values
of each case of a switch statement must evaluate to a value that can be
promoted to an int value.
93. What
is the difference between a while statement and a do while statement?
A while statement
checks at the beginning of a loop to see whether the next loop iteration should
occur. A do while statement checks at the end of a loop to see whether
the next iteration of a loop should occur. The do whilestatement will
always execute the body of a loop at least once.
94. What
modifiers can be used with a local inner class?
A local inner class may be final
or abstract.
95. When
does the compiler supply a default constructor for a class?
The compiler supplies a default
constructor for a class if no other constructors are provided.
96. If a
method is declared as protected, where may the method be accessed?
A protected method may only be
accessed by classes or interfaces of the same package or by subclasses of the class
in which it is declared.
97. What
are the legal operands of the instanceof operator?
The left operand is an object
reference or null value and the right operand is a class, interface, or array
type.
98. Are
true and false keywords?
The values true and false are
not keywords.
99. What
happens when you add a double value to a String?
The result is a String object.
100. What
is the diffrence between inner class and nested class?
When a class is defined within
a scope od another class, then it becomes inner class. If the access modifier
of the inner class is static, then it becomes nested class.
Wednesday, June 20, 2012
Java Object type casting
Java Object type casting
Converting object reference of
one type to another type is called Java object typecasting. Casting is a
programming term that means, effectively, converting a value or an
object from one type to another. The result of a cast is a new value or
object; casting does not change the original object or value.
The class of the object you're
casting and the class you're casting it to must be related by
inheritance; that is, you can cast an object only to an instance of its
class's sub- or superclass-not to any random class. Casting downward in
the class hierarchy is automatic, but casting upward is not.
There are two types of object typecasting:
1. upcasting
2. downcasting
1. upcasting
2. downcasting
Upcasting: Upcasting
is implicit and safe. Here subclass object is converted to superclass
object, because a subclass object is also a superclass object.
Downcasting:Down-casting
is potentially unsafe, because you could attempt to use a method that
the derived class does not actually implement. With this in mind,
down-casting is always explicit, that is, we are always specifying the
type we are down-casting to. Converting an instance of a subclass to an
instance of a superclass loses the information
Upcasting vs Downcasting
Given Below is a program which easily demonstrates the difference between Upcasting and downcastin in Java.
_____________________________________________________
Vehicle v1 = new Car(); / /Right . upcasting or implicit casting
Vehicle v2= new Vehicle();
Car c0 = v1; // Wrong compile time error "Type Mismatch"
//Explicit or downcasting is required
Car c1 = (Car) v1 // Right. downcasting or explicit casting . v1 has a knowledge //of Car due to line 1
Car c2= (Car) v2; //Wrong Runtime exception ClassCastException because v2 //has no knowledge of Car.
Bus b1 = new BMW(); //Wrong compile time error "type mismatch"
Car c3 = new BMW(); //Right. Upcasting or implicit casting
Car c4 = (BMW) v1; // Wrong Runtime exception ClassCastexception
Object o = v1; //v1 can only be upcast to its parent
Car c5 = (Car) v1; // v1 can be downcast to Car due to line 1 _____________________________________________________
- ClassCastException is thrown to indicate that code has attempted to cast an object to a subclass of which it is not an instance. Use exception handling mechanism to catch ClassCastException
- Use the instanceof operator to guard against incorrect casting.
what is encapsulation in java programming
Encapsulation
is one of the four fundamental OOP concepts. The other three are
inheritance, polymorphism, and abstraction. Encapsulation is the
technique of making the fields in a class private and providing access
to the fields via public methods. If a field is declared private, it
cannot be accessed by anyone outside the class, thereby hiding the
fields within the class. For this reason, encapsulation is also referred
to as data hiding. Encapsulation can be described as a protective
barrier that prevents the code and data being randomly accessed by other
code defined outside the class. Access to the data and code is tightly
controlled by an interface. The main benefit of encapsulation is the
ability to modify our implemented code without breaking the code of
others who use our code. With this feature Encapsulation gives
maintainability, flexibility and extensibility to our code.
Let us look at an example that depicts encapsulation:
public class EncapTest{
private String name;
private String idNum;
private int age;
public int getAge(){
return age;
}
public String getName(){
return name;
}
public String getIdNum(){
return idNum;
}
public void setAge( int newAge){
age = newAge;
}
public void setName(String newName){
name = newName;
}
public void setIdNum( String newId){
idNum = newId;
}
}
The
public methods are the access points to this class.s fields from the
outside java world. Normally these methods are referred as getters and
setters. Therefore any class that wants to access the variables should
access them through these getters and setters.The variables of the EncapTest class can be access as below::
/* File name : RunEncap.java */
public class RunEncap{
public static void main(String args[]){
EncapTest encap = new EncapTest();
encap.setName("chittampally kirran");
encap.setAge(22);
encap.setIdNum("12343ms");
System.out.print("Name : " + encap.getName()+
" Age : "+ encap.getAge());
}
}
This would produce following result:
Name : chittampally kirran :22
Benefits of Encapsulation:
1. The fields of a class can be made read-only or write-only.
2. A class can have total control over what is stored in its fields.
3. The
users of a class do not know how the class stores its data. A class can
change the data type of a field, and users of the class do not need to
change any of their code.
Wednesday, June 13, 2012
Overriding and Hiding Methods
Java Implements the Polymorphisim in one of the two ways that is Method Overriding and Method Overloading
Method Overriding :
Method
overriding occurs when sub class declares a method that has the same
signature (name, plus the number and the type of its parameters) and
return type as a method declared by one of its superclass. The key
benefit of overriding is the ability to define behavior thatfs specific
to a particular subclass type. An overriding method can also return a
subtype of the type returned by the overridden method. This is called a covariant return type. Which overridden version of the method to call is decided at runtime based on the object type.
The rules for overriding a method are as follows:
-
The argument list must exactly match that of the overridden method. If doesn't match we will get a overloaded method not a overriding method.
-
The return type must be same as, or a subtype of, the return type declared in the original overridden method in the superclass.
-
We can not override method marked final. Static methods can't be overridden but they can be redefined.
-
If a method can't be inherited , you cannot override it. Overriding is nothing but we are reimplementing a method that we are inherited
-
Overriding method must not throw checked exceptions that are new and broader than the those declared by the overridden method
-
The access level can't be more restrictive than the overridden method. It can be less restrictive than that of overridden method
-
The overriding method can throw any unchecked or runtime exception, regardless of weather overridden method declares the exception or not.
-
The overbidding method doesn't have to declare any exceptions that it will never throw, regardless of what the overridden method declares.
-
A subclass within the same package as the instance's superclass can override any superclass method that is not declared private or final. A subclass in a different package can only override the non-final methods declared public or protected.
-
Constructors cannot be overridden.
public class SuperClass{
public void method1() {
System.out.println("SuperClass.method1()");
}
private void method2() {
System.out.println("SuperClass.method2()");
}
public final void method3(){
System.out.println("SuperClass.method3()");
}
private final void method4(){
System.out.println("SuperClass.method4()");
}
public static void method5() {
System.out.println("SuperClass.method5()");
}
public void method6() throws Exception {
System.out.println("SuperClass.method6()");
}
private void method7(){
System.out.println("SuperClass.method7()");
}
private void method8(int x){
System.out.println("SuperClass.method8()");
}
public static void method9() {
System.out.println("SuperClass.method9()");
}
}
public class SubClass extends SuperClass {
public void method1() {
System.out.println("OverridingClass.method1()");
}
private void method2(){
System.out.println("OverridingClass.method2()");
}
//We can't override a public final method
/* public final void method3(){
System.out.println("OverridingClass.method3()");
}*/
private final void method4(){
System.out.println("OverridingClass.method4()");
}
public static void method5() {
System.out.println("OverridingClass.method5()");
}
public void method6() throws IOException{
System.out.println("OverridingClass.method6()");
}
public void method7(){
System.out.println("OverridingClass.method7()");
}
public void method8(final int x){
System.out.println("OverridingClass.method8()");
}
//A static method cannot be overridden to be non-static instance method
/*public void method9() {
System.out.println("OverridingClass.method9()");
}*/
}
public class MethodOverrdingSample{
public static void main(String[] args) {
SubClass sub = new SubClass();
SuperClass sc = new SubClass();
sub.method1();
sub.method3();
/* Since its private, the below 2 methods are not visible
sub.method2();
sub.method4();*/
sub.method5();
try {
sub.method6();
} catch (IOException e) {
e.printStackTrace();
}
sub.method7();
sub.method8(100);
sc3.method5();
SubClass subClass = new SubClass();
SuperClass supClass = (SuperClass)subClass;
supClass.method5();
supClass.method1();
}
}
To invoke a superclass version of overridden method we use a super keyword. For example
public class Superclass{
public void method1(){
System.out.println(gSuperclass Versionh);}
}
}
public class SubClass{
public method1(){
super.method1(); //Invoke first superclass code
//then do the subclass specific code
System.out.println(gSubclass Versionh);
}
}
Method Overloading :
Method overloading means to have two or more methods with same name in
the same class and its subclass with different arguments and optionally
different return type. Which overloaded version of the method to be
called is based on the reference type of the argument passed at compile
time.
The rules for overloading a method are as follows:
ðL Overloaded methods must change the argument list.
ðL Overloaded methods can change the return type.
ðL Overloaded methods can declare new or broader checked exacpetions
ðL Overloaded methods can change the access modifier.
ðL Constructors can be overloaded.
public class A {
protected A(){
System.out.println("Hi A Constructor");
}
public A(int i,int j){
System.out.println("Hi A Constructor A,B");
}
public void method1(int i){
System.out.println("Hi A in method1(i)");
}
}
public class B extends A{
public B(){
System.out.println("Hi B Constructor");
}
public B(int i, int j){
super(i,j);
System.out.println("Hi B Constructor with i,j");
}
public void method1(int j){
System.out.println("Hi B in method1(i)");
}
public void method1(int i, int j){
System.out.println("Hi B in method1(i,j)");
}
}
public class C extends A{
public C(){
System.out.println("Hi C Constructor");
}
public C(int i, int j){
super(i,j);
System.out.println("Hi C Constructor with i,j");
}
public void method1(int j){
System.out.println("Hi C in method1(i)");
}
public void method1(int i, int j){
System.out.println("Hi C in method1(i,j)");
}
}
public class D {
public static void main(String[] args) {
// TODO Auto-generated method stub
int k=0;
int l=0;
A a=new A();
B b= new B();
a= b;
C c= new C();
A ac=c;
a.method1(k);
b.method1(k,l);
b.method1(k);
c.method1(k);
//Compiler erroe! Compiler looks only at the reference and sees that Class A does not have method1(int,int) method. Compiler doesn't care about the actual object at runtime
}
}
Output for the above program
Hi A Constructor
Hi A Constructor
Hi B Constructor
Hi A Constructor
Hi C Constructor
Hi B in method1(i)
Hi B in method1(i,j)
Hi B in method1(i)
Hi C in method1(i)
Instance Methods
An instance method in a subclass with the same signature and return type as an
instance method in the superclass overrides the superclass's method.The ability of a subclass to override a method allows a class to
inherit from a superclass whose behavior is "close enough" and then to
modify behavior as needed. The overriding method has the same name,
number and type of parameters, and return type as the method it
overrides. An overriding method can also return a subtype of the type
returned by the overridden method. This is called a covariant return type.
When overriding a method, you might want to use the
@Override
annotation that instructs the compiler that you intend to override a
method in the superclass. If, for some reason, the compiler detects that
the method does not exist in one of the superclasses, it will generate
an error.Class Methods
If a subclass defines a class method with the same signature as a class method in the superclass, the method in the subclass hides the one in the superclass.The distinction between hiding and overriding has important
implications. The version of the overridden method that gets invoked is
the one in the subclass. The version of the hidden method that gets
invoked depends on whether it is invoked from the superclass or the
subclass.
let us see the following example
public class Person {
void drive()
{
System.out.println("we are iin person class"); }
}
class Father extends Person {
void drive()
{
System.out.println("father drives smmothly yar");}
}
class Son extends Father {
void drive()
{
System.out.println("Son drives roughly yar"); }
}
class Overridedemo extends Son {
public static void main(String[] args) {
Person P = new Person();
Father F = new Father();
Father S = new Son();
P.drive();
P = F;
P.drive();
P=S;
P.drive();
}
}
let us see the following example
public class Person {
void drive()
{
System.out.println("we are iin person class"); }
}
class Father extends Person {
void drive()
{
System.out.println("father drives smmothly yar");}
}
class Son extends Father {
void drive()
{
System.out.println("Son drives roughly yar"); }
}
class Overridedemo extends Son {
public static void main(String[] args) {
Person P = new Person();
Father F = new Father();
Father S = new Son();
P.drive();
P = F;
P.drive();
P=S;
P.drive();
}
}
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