Remove Duplicate in UserDefinied list

we can remove duplicate object in user definied list by overriding equals and hashcode method in java.
first create Java Bean.

Person.java
-------------

1. package com.utilitySample;
2. 
   
3. public class Person{
4. 
   
5. private String name;
6. 
   
7. public String getName() {
8. return name;
9. }
10. 
    
11. public void setName(String name) {
12. this.name = name;
13. }
14. 
    
15. /**
16.  * we have to override equals method to avaoid duplicates in userDefined list.
17.  */
18. public boolean equals(Object obj) {
19. boolean result = false;
20. Person person = (Person) obj;
21. 
    
22. if (this.getName().equalsIgnoreCase(person.getName())){
23. result = true;
24. }
25. return result;
26. }
27. 
    
28. public int hashCode() {
29. // TODO Auto-generated method stub
30. return 1;
31. }
32. 
    
33. }

Then create your main java class.

RemDupList.java
------------------

1. package com.utilitySample;
2. 
   
3. import java.util.ArrayList;
4. import java.util.HashSet;
5. import java.util.List;
6. import java.util.Set;
7. 
   
8. public class RemDupList {
9. 
   
10. public static void main(String[] args) {
11.             List<Person> personList = new ArrayList<Person>();
12.    Person person = new Person();
13.    person.setName("amazon");
14.    personList.add(person);
15.    person = new Person();
16.    person.setName("amazon");
17.    personList.add(person);
18.    person = new Person();
19.    person.setName("stalin");
20.    personList.add(person);
21.    person = new Person();
22.    person.setName("stalin");
23.    personList.add(person);
24.    for (Person pers:personList){
25.     System.out.println("Before removing duplicates ::"+pers.getName());
26.    }
27.    Set<Person> personSet = new HashSet<Person>(personList);
28.    for (Person pers:personSet){
29.     System.out.println("After removing duplicates ::"+pers.getName());
30.    }
31.    List<Person> personList2 = new ArrayList<Person>();
32.    personList2.addAll(personSet);
33.    System.out.println("size ::"+personList2.size());
34.    for (int i = 0; i < personList2.size(); i++) {
35. System.out.println("value ::"+personList2.get(i).getName());
36. }
37.   }
38. 
    
39. }

 Output :

 Before removing duplicates ::amazon
 Before removing duplicates ::amazon
 Before removing duplicates ::stalin
 Before removing duplicates ::stalin
 After removing duplicates ::stalin
 After removing duplicates ::amazon
 size ::2
 value ::stalin
 value ::amazon