Counting the number of duplicate Object in ArrayList (number of times repeated Objects)

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
public class DupCount {
public static void main(String []args){
List l=new ArrayList();
l.add("a");
l.add("a");
l.add("b");
l.add("c");
l.add("d");
l.add("b");
l.add("b");
l.add("d");
System.out.println(l);
System.out.println("count of a:" +Collections.frequency(l, "a") );
Set<String> uniqueSet =new HashSet<String>(l);
for(String temp : uniqueSet){
System.out.println(temp+ ":" + Collections.frequency(l, temp));
}
}

}
=================Output=====================
[a, a, b, c, d, b, b, d]
count of a:2
d:2
b:3
c:1
a:2