Java Collection How to - Remove duplicate items from a List

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Question

We would like to know how to remove duplicate items from a List.

Answer

import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
//w  w  w  . ja v a2  s .c o  m
public class Main {
  public static void main(String[] argv) {
    List<String> arrayList1 = new ArrayList<String>();

    arrayList1.add("A");
    arrayList1.add("A");
    arrayList1.add("B");
    arrayList1.add("B");
    arrayList1.add("B");
    arrayList1.add("C");

    HashSet<String> hashSet = new HashSet<String>(arrayList1);

    List<String> arrayList2 = new ArrayList<String>(hashSet);

    for (Object item : arrayList2)
      System.out.println(item);
  }
}

The code above generates the following result.

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