How to sort user defined object in ArrayList [duplicate]

Question

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Closed 12 years ago.

Possible Duplicate:
How to sort an arraylist of objects by a property?

 public static void main(String args[]){
 List<Emp> unsortList = new ArrayList<Emp>();
 unsortList.add(new Emp(109));
 unsortList.add(new Emp(106));
 unsortList.add(new Emp(103));
 unsortList.add(new Emp(108));
 unsortList.add(new Emp(101));
 }
public class Emp {
Integer eid;
public Emp(Integer eid) {
 this.eid=eid;
}
}

Emp is user defined class & stored in ArrayList. How sort ArrayList.

• Egor: You probably should have tried Google before asking your question here, there are LOTS of info on this topic.

Answer 1

Check out Collections#sort(List list, Comparator c)

It allows you supply your own Comparator which you can use to define how the objects will be matched

Answer 2

Implement Comparable<Emp> and use Collections.sort to sort the list

public class Emp implements Comparable<Emp> {
 Integer eid;
 public Emp(Integer eid) {
 this.eid = eid;
 }
 @Override
 public int compareTo(Emp o) {
 return eid.compareTo(o.eid);
 }
}