Monday 8 May 2017

Sort elements in ArrayList in java

To sort the elements of list be it linked list or array list, you can use
Collections.sort(List list);

Note: 
* Strings are sorted in lexicographic order(see example below)
* Dates are sorted in chronological order(In our example replace String with Date and see the result)
* Integers are sorted in numeric order(In our example replace String with Integer and see the result)


In the given example, the sorting method is highlighted in similar background color. Lets look at each step closely. Its pretty simple to sort a list.
Lets have a look.

package javaRadarArrayList;

import java.util.ArrayList;
import java.util.Collections;
import java.util.Iterator;

public class SortArrayList {

      public static void main(String[] args) {
            //create Array List
            ArrayList<String> javaRadarList = new ArrayList<String>();

            //Add elements to ArrayList
            javaRadarList.add("Java");
            javaRadarList.add("Jquery");
            javaRadarList.add("Spring");
            javaRadarList.add("Hibernate");
            javaRadarList.add("EJB");

            //use iterator to traverse list
            System.out.println("Before sorting: " +javaRadarList);

            Collections.sort(javaRadarList); //sorting list element

            Iterator<String> itrAfterSort = javaRadarList.iterator();

            System.out.println("After Sorting:");
            while(itrAfterSort.hasNext()){
                  String token = itrAfterSort.next();
                  System.out.println(token);
            }

      }

}


OUTPUT:


Before sorting: [Java, Jquery, Spring, Hibernate, EJB]
After Sorting:
EJB
Hibernate
Java
Jquery
Spring

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