In Order to Convert TreeSet to AraryList in Java , We have couple of ways . We Knew that ArrayList In Java is a ordered collection and allow duplicate element . But TreeSet in Java is avoids duplicates. We Can convert Set to List in java using below method
1. Using ArrayList Constructor –
Firstly , We will create a set and pass as a argument in ArrayList constructor. If you didn’t know much about ArrayList constructor i will recommenced to you first read this How to create ArrayList In Java .
import java.util.ArrayList;
import java.util.List;
import java.util.Set;
import java.util.TreeSet;
public class TreeSetToList {
public static void main(String[] args) {
Set<String> ts = new TreeSet<String>();
ts.add("mumbai");
ts.add("delhi");
ts.add("kolkata");
ts.add("chandigarh");
ts.add("dehradun");
// print treeset
System.out.println(" ts ="+ts);
List<String> list = new ArrayList<String>(ts);
for (String str : list) {
System.out.println(" List Element is = "+str);
}
}
}Output:
ts =[chandigarh, dehradun, delhi, kolkata, mumbai]
List Element is = chandigarh
List Element is = dehradun
List Element is = delhi
List Element is = kolkata
List Element is = mumbai2. Using AddAll() Method
ArrayList Provides AddAll() Method Which can append element in the collection .With the help of addAll() method we can convert set to arraylist/linkedlist/list. For this we will create a hashset aadd element in to it. Now we create a list and add element of set in to list with the help of addAll() method as.
import java.util.ArrayList;
import java.util.Set;
import java.util.TreeSet;
public class ArrayToListByAllAdd {
public static void main(String[] args) {
Set<String> ts = new TreeSet<String>();
ts.add("mumbai");
ts.add("delhi");
ts.add("kolkata");
ts.add("chandigarh");
ts.add("dehradun");
ArrayList<String> arrayList = new ArrayList<String>();
arrayList.addAll(ts);
System.out.println("list is ="+ arrayList);
}
}Output :
list is =[chandigarh, dehradun, delhi, kolkata, mumbai]We can convert Set to LinkedList Using these Ways.
Reference :