Remove duplicate items from an ArrayList : ArrayList « Collections « Java Tutorial

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Java Tutorial » Collections » ArrayList

9. 11. 33. Remove duplicate items from an ArrayList


import java.util.ArrayList;

import java.util.HashSet;

import java.util.List;



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);

  }

}

/*

A

B

C

*/

9. 11. ArrayList
	9. 11. 1.	ArrayList Class
	9. 11. 2.	Creating an ArrayList
	9. 11. 3.	A boolean is being stored and then retrieved from an ArrayList
	9. 11. 4.	The final constructor is the copy constructor: creating a new ArrayList from another collection
	9. 11. 5.	Adding Single Elements
	9. 11. 6.	Adding elements in the middle of a List
	9. 11. 7.	Add an element to specified index of ArrayList
	9. 11. 8.	Append all elements of other Collection to ArrayList
	9. 11. 9.	Insert all elements of other Collection to Specified Index of ArrayList
	9. 11. 10.	To create a read-only list, use the unmodifiableList() method of the Collections class
	9. 11. 11.	Adding Another Collection
	9. 11. 12.	Getting an Element
	9. 11. 13.	Get Sub List of ArrayList
	9. 11. 14.	Removing a Single Element
	9. 11. 15.	Removing Another Collection(Removing elements): public boolean removeAll(Collection c)
	9. 11. 16.	Retaining Another Collection: public boolean retainAll(Collection c)
	9. 11. 17.	Removing Ranges
	9. 11. 18.	Fetching Elements with iterator
	9. 11. 19.	Checking for Existence: public boolean contains(Object element)
	9. 11. 20.	Checking for Position
	9. 11. 21.	Checking for List Containment: public boolean containsAll(Collection c)
	9. 11. 22.	Replacing Elements with the set() method: public Object set(int index, Object element)
	9. 11. 23.	Checking Size: public int size(), public boolean isEmpty()
	9. 11. 24.	Checking Capacity
	9. 11. 25.	After adding all of the elements, call the trimToSize() method
	9. 11. 26.	Copying and Cloning Lists: public Object clone()
	9. 11. 27.	ArrayList implements the empty Serializable interface
	9. 11. 28.	Checking for Equality
	9. 11. 29.	Copying elements out of a list into an array
	9. 11. 30.	Convert a List (ArrayList) to an Array with zero length array
	9. 11. 31.	Convert a List (ArrayList) to an Array with full length array
	9. 11. 32.	Copy all elements of ArrayList to an Object Array
	9. 11. 33.	Remove duplicate items from an ArrayList
	9. 11. 34.	Removing All Elements
	9. 11. 35.	Looping through a Collection object: while loop, iterator, and for each
	9. 11. 36.	If an ArrayList contains a given item
	9. 11. 37.	Search an element of ArrayList with indexOf and lastIndexOf
	9. 11. 38.	Get container with Iterator from ArrayList

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