5 different places to define Object of a class in java

• Object of a class can be defined at 5 different places.

1. Defining object of a class as local to a method or local variable.
2. Defining object of a class as an instance variable of another class.
3. Defining object of a class as the parameter of the method.
4. Defining  object of a class as the return data type of the method.
5. Defining object of a class as the static variable or class variable of another class.

1.Defining object of a class as local to a method or local variable:

1. package com.instanceofjava;
2.  
3.  public class ObjectInsideMethod { 
4.  
5.    int val;  
6.  
7. public int getVal()
8.  {     
9.   
10.   return val;   
11.  
12.   }
13.  
14. public void setVal(int val) {  
15.  
16.        this.val = val;
17.  
18.  }
19.  
20. public void createObject(){ 
21.   
22.        ObjectInsideMethod obj=new ObjectInsideMethod();        
23.         obj.setVal(10);    
24.  
25.       System.out.println(obj.getVal());
26.  
27.   }
28.  
29.    public static void main(String[] args) {
30.  
31.         ObjectInsideMethod obj=new ObjectInsideMethod();
32.         obj.createObject();
33.  
34.  }
35. }

2.Defining object of a class as an instance variable of another class:

1. package instanceofjava;
2.  
3. class sample{
4.  
5.   int num;
6.  
7. public void setNum(int num) {
8.         this.num= num;
9. }
10.  
11. public String getNum() {
12.         return num;
13.     }
14. }

1. package com.instanceofjava; 
2.  
3. public class ObjectAsInstanceVariable { 
4.  
5.  Sample sample= new Sample ();   
6.  
7. public static void maina(String args[]){  
8.  
9.      ObjectAsInstanceVariable obj=new ObjectAsInstanceVariable();    
10.      obj.sample.setNun(10);    
11.  
12.     }
13.   }  

3.Defining object of a class as the parameter of the method.

1. package com.instanceofjava; 
2.  
3.  public class Employee 
4. {  
5.  
6.    String name;  
7.    int id;   
8.    String address;    
9.  
10. Employee(String name, int id, String address){ 
11.  
12.         this.name=name; 
13.         this.id=id; 
14.         this.address=address; 
15.  }   
16.  
17.  public boolean comapreEmpids(Employee e){
18.  
19. if(this.id==e.id){ 
20.  
21. return true;  
22.  
23. }
24. return false;
    
25. }   
26.  
27.  public static void main(String args[]){
28.  
29.      Employee empone= new Employee("sai", 1, "hyderabad");
30.      Employee emptwo= new Employee("sai", 2, "Khammam");
31.  
32.      boolean check=empone.comapreEmpids(emptwo);
33.      System.out.println(check); //returns false
34.  
35.     } 
36. }

 

 4.Defining  object of a class as the return data type of the method.

1. package com.instanceofjava;  
2.  
3. public class Singleton
4. {
5. 
   
6. static Singleton obj;
7.  
8.  private  Singleton(){
9.  } 
10.  
11. public static Singleton getInstance(){
12.  
13. if(obj!=null){ 
14. return  obj; 
15. }
16. else{
17. obj=new Singleton();
18. return obj;
19. }
20.  
21. }
22.  
23. public static void main(String[] args) {
24.  
25.  Singleton obj=Singleton.getInstance();
26.  Singleton obj1=Singleton.getInstance();
27.  
28. }
29.  }

5.Defining object of a class as the static variable or class variable of another class

1. package com.instanceofjavaforus; 
2. public class Sample {
3.  
4.      public void diplsyString(String str){
5.          System.out.println(str);
6. }
7.  
8. } 
9.  
10.  
11. package com.instanceofjavaforus;
12.  
13. public class TestDemo {
14.  
15.   public static Sample sample= new Sample();
16.  
17.   public static void main(String args[]){
18.  
19. TestDemo.sample.diplsyString("Hello Hyderabd");
20.  
21.  }
22. }

This scenario used in System.out.println();

You Might Like:

1.What are all the Five different ways to create object in java

2.Java Example program to restrict a class from creating not more than three objects 

3.Six different ways to iterate list in java