Polymorphism program

Compile time polymorphism program

METHOD OVERLOADING

1:- No of Arg ( Method overloading )

class Demo
 {
     void show(int a)
     {
         
         System.out.println("Method 1  " +a);
     }
     
     void show(int a,int b)
     {
         System.out.println("method 2  "  +a+" "+ b);
     }
    public static void main(String arg[]){
        
    Demo  obj= new Demo();
    obj.show(34);
    obj.show(22,33);
 }
 }
 OutPUT

 C:\java>javac Testing.java

C:\java>java Demo
Method 1  34
method 2  22 33

C:\java>

2:- seq of arg ( Method overloading )

class Demo
 {
     void show(int a,String b)
     {
         
         System.out.println("Method 1  " +a+"  "+ b);
     }
     
     void show(String b,int a)
     {
         System.out.println("method 2  "  +a+" "+ b);
     }
    public static void main(String arg[]){
        
    Demo  obj= new Demo();
    obj.show(34,"java");
    obj.show("java",34);
 }
 }
 Output
 
 C:\java>javac Testing.java

C:\java>java Demo
Method 1  34  java
method 2  34 java
 
C:\java>

3:-Type of Arg (Method overloading )

class Demo
 {
     void show(String a)
     {
         
         System.out.println("Method 1  " +a);
     }
     
     void show(int a)
     {
         System.out.println("method 2  "  +a);
     }
    public static void main(String arg[]){
        
    Demo  obj= new Demo();
    obj.show("java");
    obj.show(34);
 }
 }
 //Output
 
C:\java>javac Testing.java

C:\java>java Demo
Method 1  java
method 2  34

C:\java>

4:-

1.Can we achieve method overloading by changing the return type of method only?

Ans:-Ans:- in java, method overloading is not possible by changing the return type of the method only because of ambiguity.

class Demo
 {
     int  show(String a)
     {
         
         System.out.println("Method 1  " +a);
     }
     
     float show(String a)
     {
         System.out.println("method 2  "  +a);
     }
    public static void main(String arg[]){
        
    Demo  obj= new Demo();
    obj.show("java");
    obj.show("java");
 }
 }
 
C:\java>javac Testing.java
Testing.java:9: error: method show(String) is already defined in class Demo
         float show(String a)
               ^
1 error

C:\java>

5:- Can we overload java main () method ?

Ans:- yes ,we can have any number of main method overloading.This is because JVM always calls main() method which receives string arrays as arguments only.

MainMethodOverload1

class Test { 

public static void main(String[] args) 
{ 
System.out.println("method 1"); 
} 
public static void main(int a)
{ 
System.out.println("method 2"); 
} 
} 
 
C:\java>javac Testing.java

C:\java>java Test
method 1

C:\java>

MainMethodOverload2

class Demo
{   
// Overloaded main() method 1   
//invoked when an int value is passed  
public static void main(Integer args)   
{   
System.out.println("Overloaded main() method invoked that parses an integer argument");   
}   
// Overloaded main() method 2   
//invoked when a char is passed  
public static void main(char args)   
{   
System.out.println("Overloaded main() method invoked that parses a char argument");   
}   
//Original main() method  
public static void main(String[] args)   
{   
System.out.println("Original main() method invoked");   
}   
}  
C:\java>javac Testing.java

C:\java>java Demo
Original main() method invoked

C:\java>

or

MainMethodOverload3

 class Demo
{  
//original main() method  
public static void main(String args[])  
{  
Demo mmo= new Demo ();  
//calling overloaded main() method from the original main() method  
mmo.main();  
}  
//overloaded main() method  
public static void main()  
{  
System.out.println("Overloaded main() method invoked");  
}  
}  


C:\java>javac Testing.java

C:\java>java Demo
Overloaded main() method invoked

C:\java>

MainMethodOverload4

 class Demo
{  
//original main() method  
public static void main(String args[])  
{  
Demo mmo= new Demo ();  
//calling overloaded main() method from the original main() method  
mmo.main();  
mmo.main(23);
mmo.main("sonu");


}  
//overloaded main() method  
public static void main( )  
{  
System.out.println("Overloaded main() method invoked");  
}  
public static void main(Integer p)
{
    System.out.println("Overloaded main() method invoked2" +" "+ p);  
}
public static void main(String args)
{
    System.out.println("Overloaded main() method invoked3"+ args );  
}

}  


C:\java>javac Testing.java

C:\java>java Demo
Overloaded main() method invoked
Overloaded main() method invoked2 23
Overloaded main() method invoked3sonu

C:\java>

MainMethodOverload5

 class Demo  
{   
//Overloaded main() method 1   
public static void main(boolean args)   
{   
if (args)   
{   
System.out.println("First overloaded main() method executed");   
System.out.println(args);   
}   
}   
//Overloaded main method 2   
public static void main(String str)   
{   
System.out.println("Second overloaded main() method executed");   
System.out.println(str);   
}   
//Overloaded main method 3   
public static void main(int args)   
{   
System.out.println("Third overloaded main() method executed");   
System.out.println(args);   
}   
//Original main() method  
public static void main(String[] args)   
{   
System.out.println("Original main() method executed");   
System.out.println("Hello");   
//invoking overloaded main() method 1   
Demo.main(true);   
//invoking overloaded main() method 2  
Demo.main("mango");  
//invoking overloaded main() method 3   
Demo.main(112);   
}   
}  


C:\java>javac Testing.java

C:\java>java Demo
Original main() method executed
Hello
First overloaded main() method executed
true
Second overloaded main() method executed
mango
Third overloaded main() method executed
112

C:\java>

Case 1

class Demo { 

public static void main(String[] argos) 
{ 
System.out.println("1"); 
Demo t= new Demo(); 
t.main(20); 
} 
public static void main(int a) 
{ 
System.out.println(a); 
} 
} 

C:\java>javac Testing.java

C:\java>java Demo
1
20

C:\java>

class Demo { 

void show(int a) 
{ 
System.out.println("int method"+a); 
} 

void show(String a) 
{ 
System.out.println(" String method"+a); 
} 
public static void main(String[] args) 
{ 
Demo t= new Demo(); 
t.show(30); 
t.show("sonu"); 
t.show("java"); //automatic promotion 
} 
} 
C:\java>javac Testing.java

C:\java>java Demo
int method30
 String methodsonu
 String methodjava

C:\java>

Case 2

class Testing
{ 
void show (char a) 
{ 
System.out.println("object method");

} 
void show (String a) 
{ 
System.out.println("String method"); 
} 
public static void main(String[] args) 
{ 
Testing t= new Testing(); 

t.show('a') ; 
t.show("Deepak"); 

} 

} 

//
C:\java>javac Testing.java

C:\java>java Testing
object method
String method

C:\java>

Case 3

class Demo 
{ 
void show (StringBuffer a) 
{ 
System.out.println("String buffer method"+a); 
}
void show (String a) 
{ 
System.out.println("String method"+a); 
} 
public static void main(String[] args) 
{
Demo t= new Demo(); 
t.show("Deepak"); 
t.show(new StringBuffer("Deepak2")); 
t.show("null"); 

} 

} 

C:\java>javac Testing.java

C:\java>java Demo
String methodDeepak
String buffer methodDeepak2
String methodDeepak

C:\java>

Case 4

class Demo
{ 
void show(int a,float b) 
{
System.out.println("int float method"); 
} 
void show(float a, int b) 
{ 
System.out.println("Float int method"); 
} 
public static void main(String[] args) 
{ 
Demo t= new Demo(); 
t.show(10,50.01f); 
t.show(50.01f,40); 
t.show(10,20); 
}
}

C:\java>javac Testing.java

C:\java>java Demo
int float method
Float int method

C:\java>

class Demo
{ 
void show(int a,float b) 
{
System.out.println("int float method"); 
} 
void show(float a,int b) 
{ 
System.out.println("Float int method"); 
} 
public static void main(String[] args) 
{ 
Demo t= new Demo(); 
t.show(10,50.01f);  
t.show(50.01f,40); 
t.show(10,20.0f); 
}
}

C:\java>javac Testing.java

C:\java>java Demo
int float method
Float int method
int float method

C:\java>

Case 5

class Demo{ 
void show(int a) 
{ 
System.out.prinln("int method"); 
} 
void show(int a) 
{ 
System.out.println("intger method"); 
} 
public static void main(String args){ 
Demo t= new Demo(); 
t.show(45); 
t.show(45,45,24); 
t.show(); 

} }   ya program 'Run nahi hua hai

class Demo
{
    
static void meth()
{
    System.out.println("Good morning bro"); 
}
static void meth(int a)
{
System.out.println("Good morning "+ a+"bro")    ;// parameter
}
public static void main(String args[])
{
    
    meth(45); //argument
    meth();
    
    
    
}
}
 C:\java>javac Testing.java

C:\java>java Demo
Good morning 45bro
Good morning bro

C:\java>

Method overriding

class Demo 
{ 
void show( String a,int b) 
{ 
System.out.println("method 1"+"  "+a+"  "+b); 
} 
} 
class Demo2 
{ 
void show( String a,int b) 
{ 
System.out.println("method 2"+"  "+a); 
} 
public static void main(String args[]) 
{ 
Demo s1= new Demo(); 
Demo2 s2= new Demo2();
s1.show("sonu"); 
s2.show(3); 
} 
}

C:\java>javac Testing.java

C:\java>java Demo2
method 1sonu
method 23

C:\java>

Type of arrgument

class Demo 
{ 
void show( String a) 
{ 
System.out.println("method 1"+"  "+a); 
} 
} 
class Demo2 
{ 
void show( String a) 
{ 
System.out.println("method 2"+"  "+a); 
} 
public static void main(String args[]) 
{ 
Demo s1= new Demo(); 
Demo2 s2= new Demo2();
s1.show("sonu"); 
s2.show("so"); 
} 
}

C:\java>javac Testing.java

C:\java>java Demo2
method 1  sonu
method 2  so

C:\java>

Case 1

1.Do overring method must have same return type (or subtype)?

From java 5.0 onwords it is possible to have different return type for a overriding method in child class , but child’s return types should type of parents return type. This phenomena is known as covariant return type .

Case 2

Q2 :- overriding and Access- modifiers

Ans:- the access modifier for an overriding method can allow more ,but not less, access than the overridden method.For example, a protected instance method in the super-class can be made public .but not private ,in the subclass. Doing so , will generate compile-time error.

class Demo 
{ 
object show() 
{ 
System.out.println( "method 1"); 
} 
} 
class Demo2 extends Demo 
{  
public String show() 
{  
System.out.println("method 2") ;
} 
public static void main (String []args) 
{
Demo2 t= new Demo2(); 

t.show(); 

Demo obj = new Demo(); 
Obj.show();    this program not Run
}
} 

Method overloading

No of arguments

Program No:- 1

Squance of arguments

program 1

program 2

Type of arguments

Program :- 1

Program :-2

Method overriding

large fornt size

Program No:- 1

public class Test {
void show(){
System.out.println("method 1");
}
}
class xyz extends Test{

void show(){
System.out.println("method 2");
}
public static void main(String[] args) {
Test obj =new Test();
obj.show();
}
}

Output

method 1

Program No:- 2

public class Test {
String show(){

System.out.println("method 1");
return null;
}
}
class xyz extends  Test{

String show(){
System.out.println("method 2");
return null;
}
public static void main(String[] args) {
  Test obj =new  Test();
obj.show();
}
}

output

method 1

Program No:- 3

  public class  Test {
int show(){

System.out.println("method 1");
return 0;
}
}
class xyz extends ex9{

int show(){
System.out.println("method 2");
return 0;
}
public static void main(String[] args) {
   Test obj =new  Test();
obj.show();
}
}

output

method 1

Program No:- 4

public class  Test {
Object show(){

System.out.println("method 1");
return null;
}
}
class xyz extends  Test{

String show(){
System.out.println("method 2");
return null;
}
public static void main(String[] args) {
  Test obj =new  Test();
obj.show();
}
}

output

method 1

Program No:- 5

public class Test {
Object show(){

System.out.println("method 1");
return null;
}
}
class xyz extends Test{
StringBuffer show(){
System.out.println("method 2");
return null;
}
public static void main(String[] args) {
Test obj =new Test();
obj.show();
}
}

output

method 1

Program No:- 6

public class Test {
Object show(){

System.out.println("method 1");
return null;
}
}
class xyz extends Test{
StringBuilder show(){
System.out.println("method 2");
return null;
}
public static void main(String[] args) {
Test obj =new Test();
obj.show();

xyz obj2 =new xyz();
obj2.show();
}
}

output

method 1

method 2

Program No:- 7

public class Test {
Object show(){

System.out.println("method 1");
return null;
}
}
class xyz extends Test{
Number show(){
System.out.println("method 2");
return null;
}
public static void main(String[] args) {
Test obj =new Test();
obj.show();

xyz obj2 =new xyz();
obj2.show();

}
}

output

method 1

method 2

Program No:- 8

public class Test {
Object show(){

System.out.println("method 1");
return null;
}
}
class xyz extends Test{
Character show(){
System.out.println("method 2");
return null;
}
public static void main(String[] args) {
Test obj =new Test();
obj.show();

xyz obj2 =new xyz();
obj2.show();

}
}

output

method 1

method 2

Program No:- 9

public class Test {
Object show(){

System.out.println("method 1");
return null;
}
}
class xyz extends Test{
Boolean show(){
System.out.println("method 2");
return null;
}
public static void main(String[] args) {
Test obj =new Test();
obj.show();

xyz obj2 =new xyz();
obj2.show();

}

output

method 1

method 2

Program No:- 10

           public class Test {
Number show(){

System.out.println("method 1");
return 0;
}
}
class xyz extends Test{
Byte show(){
System.out.println("method 2");
return 0;
}
public static void main(String[] args) {
Test obj =new Test();
obj.show();

xyz obj2 =new xyz();
obj2.show();

}
}

output

method 1

method 2

Program No:- 11

public class Test {
Number show(){

System.out.println("method 1");
return 0;
}
}
class xyz extends Test{
Short show(){
System.out.println("method 2");
return 0;
}
public static void main(String[] args) {
Test obj =new Test();
obj.show();

xyz obj2 =new xyz();
obj2.show();

}
}

output

method 1

method 2

Program No:- 12

public class Test {
Number show(){

System.out.println("method 1");
return 0;
}
}
class xyz extends Test{
Integer show(){
System.out.println("method 2");
return 0;
}
public static void main(String[] args) {
Test obj =new Test();
obj.show();

xyz obj2 =new xyz();
obj2.show();

}
}

output

method 1

method 2

Program No:- 13

public class Test {
Number show(){

System.out.println("method 1");
return 0;
}
}
class xyz extends Test{
Long show(){
System.out.println("method 2");
return 0;
}
public static void main(String[] args) {
Test obj =new Test();
obj.show();

xyz obj2 =new xyz();
obj2.show();

}
}

Program No:- 13

public class Test {

Number show()

System.out.println("method 1");

return 0;

}

class xyz extends Test{

Long show(){

System.out.println("method 2");

return null;

}

public static void main(String[] args) {

Test obj =new Test();

obj.show();

xyz obj2 =new xyz();

obj2.show();

}

output

method 1

method 2

Program No:- 13

public class Test {

Number show(){

System.out.println("method 1");

return 0;

}

class xyz extends Test{

Float show(){

System.out.println("method 2");

return null;

}

public static void main(String[] args) {

Test obj =new Test();

obj.show();

xyz obj2 =new xyz();

obj2.show();

}

output

method 1

method 2

Program No:- 14

public class Test {

Number show(){

System.out.println("method 1");

return 0;

}

class xyz extends Test{

Double show(){

System.out.println("method 2");

return null;

}

public static void main(String[] args) {

Test obj =new Test();

obj.show();

xyz obj2 =new xyz();

obj2.show();

}

output

method 1

method 2

Program No:- 15

Overriding and Access-Modifierspublic class Test {

Object show(){

System.out.println("method 1");

return null;

}

}class xyz extends Test{

public String show(){

System.out.println("method 2");

return null;

}

public static void main(String[] args) {

Test obj =new Test();

obj.show();

xyz obj2 =new xyz();

obj2.show();

}

output

method 1

method 2

Program No:- 16

public class Test {
Object show(){
System.out.println("method 1");
return null;
}
}class xyz extends Test{
protected String show(){
System.out.println("method 2");
return null;
}
public static void main(String[] args) {
Test obj =new Test();
obj.show();
xyz obj2 =new xyz();
obj2.show();
}
}

output

method 1

method 2

Program No:- 17

public class Test {

public void show(){

System.out.println("method 1");

}

}class xyz extends Test{

public void show(){

System.out.println("method 2");

}

public static void main(String[] args) {

Test obj =new Test();

obj.show();

xyz obj2 =new xyz();

obj2.show();

}

output

method 1

method 2

Program No:- 17

public class Test {

protected void show(){

System.out.println("method 1");

}

}class xyz extends Test{

protected void show(){

System.out.println("method 2");

}

public static void main(String[] args) {

Test obj =new Test();

obj.show();

xyz obj2 =new xyz();

obj2.show();

}

Program No:- 17

public class Test {

protected void show(){

System.out.println("method 1");

}

}class xyz extends Test{

public void show(){

System.out.println("method 2");

}

public static void main(String[] args) {

Test obj =new Test();

obj.show();

xyz obj2 =new xyz();

obj2.show();

}

overriding & Exception Handling

Program No:- 18

public class Test {

void show(){

System.out.println("method 1");

}

}class xyz extends Test{

void show() throws ArithmeticException

{

System.out.println("method 2");

}

public static void main(String[] args) {

Test obj =new Test();

obj.show();

xyz obj2 =new xyz();

obj2.show();

}

output

method 1

method 2

Program No:- 19

Program No:- 20

public class Test {

void show() throws RuntimeException{

System.out.println("method 1");

}

}class xyz extends Test{

void show() throws RuntimeException

{

System.out.println("method 2");

}

public static void main(String[] args) {

Test obj =new Test();

obj.show();

xyz obj2 =new xyz();

obj2.show();

}

output

method 1

method 2

Program No:- 21

public class Test {

void show() throws RuntimeException{

System.out.println("method 1");

}

}class xyz extends Test{

void show() throws ArithmeticException

{

System.out.println("method 2");

}

public static void main(String[] args) {

Test obj =new Test();

obj.show();

xyz obj2 =new xyz();

obj2.show();

}

Program No:- 22

public class Test {

void show() throws RuntimeException{

System.out.println("method 1");

}

}class xyz extends Test{

void show()

{

System.out.println("method 2");

}

public static void main(String[] args) {

Test obj =new Test();

obj.show();

xyz obj2 =new xyz();

obj2.show();

}

Program No:- 22

Case 4 :- overriding and Abstract Method

Program No:- 23

Program No:- 24

abstract class Test {

void show() throws RuntimeException{

System.out.println("method 1");

}

}class xyz extends Test{

void show()

{

System.out.println("method 2");

}

public static void main(String[] args) {

// Test obj =new Test();

// obj.show();

xyz obj2 =new xyz();

obj2.show();

}

output

method 2

Program No:- 25

abstract class Test {

abstract void display();

void show() throws RuntimeException{

System.out.println("method 1"); }

}class xyz extends Test{

void display(){

}

void show()

{

System.out.println("method 2");

}

public static void main(String[] args) {

// Test obj =new Test();

// obj.show();

xyz obj2 =new xyz();

obj2.show();

}

output

method 2

Program No:- 26

Program No:- 27

Program No:- 28

interface i1

{

void display1();

}

abstract class Test {

abstract void display();

void show()

{ System.out.println("method 1"); }

}class xyz implements i1{

public void display1(){

}

void display(){

}

void show() {

System.out.println("method 2");

}

public static void main(String[] args) {

xyz obj2 =new xyz();

obj2.show();

}

output

method 2

Program No:- 29

abstract class Test {

void show()

{ System.out.println("method 1");

}

}class xyz extends Test{

void show() {

super.show();

System.out.println("method 2");

}

public static void main(String[] args) {

xyz obj2 =new xyz();

obj2.show();

}

output

method 1

method 2

Program No:- 30

Program No:- 31

Program No:- 32

synchronized and stricfp

Program No:- 33

class Test {

synchronized void show()

{ System.out.println("method 1");

}

}class xyz extends Test{

void show() {

System.out.println("method 2");

}

public static void main(String[] args) {

Test obj2 =new Test();

obj2.show();

}

output

method 1

Program No:- 33

class Test {

strictfp void show()

{ System.out.println("method 1");

}

}class xyz extends Test{

void show() {

System.out.println("method 2");

}

public static void main(String[] args) {

Test obj2 =new Test();

obj2.show();

}

output

method 1

Program No:- 1

Program No:- 2

Program No:- 3

Program No:- 4

Program No:- 5

Overriding and Access-Modifiers

Program No:- 6

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