Java Collection Tutorial - ArrayList Example

Example

The following code shows how to get Size of ArrayList and loop through elements.

/*  w  w  w. j  av  a 2  s .  com*/
import java.util.ArrayList;

public class Main {
  public static void main(String[] args) {
    ArrayList<String> arrayList = new ArrayList<String>();

    arrayList.add("1");
    arrayList.add("2");
    arrayList.add("3");
    arrayList.add("java2s.com");
    
    int totalElements = arrayList.size();
    for (int index = 0; index < totalElements; index++)
      System.out.println(arrayList.get(index));
  }
}

The code above generates the following result.

Example 2

The following code shows how to traverse through ArrayList in forward direction using ListIterator.

//from w  w  w .jav a  2s  . com
import java.util.ArrayList;
import java.util.ListIterator;

public class Main {
  public static void main(String[] args) {
    ArrayList<String> aList = new ArrayList<String>();
    aList.add("1");
    aList.add("2");
    aList.add("3");
    aList.add("4");
    aList.add("java2s.com");

    ListIterator listIterator = aList.listIterator();
    while (listIterator.hasNext()){
      System.out.println(listIterator.next());
    }
  }
}

The code above generates the following result.

Example 3

The following code shows how to get the size of an arraylist after and before add and remove methods.

//from   w ww . ja  v  a 2s . c o m
import java.util.ArrayList;

public class Main {
  public static void main(String args[]) {
    ArrayList<String> al = new ArrayList<String>();

    System.out.println("Initial size of al: " + al.size());

    al.add("C");
    al.add("A");
    al.add("E");
    al.add("B");
    al.add("D");
    al.add("F");
    al.add(1, "java2s.com");

    System.out.println("Size of al after additions: " + al.size());

    System.out.println("Contents of al: " + al);

    al.remove("F");
    al.remove(2);

    System.out.println("Size of al after deletions: " + al.size());
    System.out.println("Contents of al: " + al);
  }
}

The code above generates the following result.

Example 4

The following code shows how to use set method to change the value in an array list.

//from  w  ww.j a v  a2  s. c o m
import java.util.ArrayList;

public class Main {
  public static void main(String[] a) {
    ArrayList<String> nums = new ArrayList<String>();
    nums.clear();
    nums.add("One");
    nums.add("Two");
    nums.add("Three");

    System.out.println(nums);
    nums.set(0, "Uno");
    nums.set(1, "Dos");
    nums.set(2, "java2s.com");
    System.out.println(nums);
  }
}

The code above generates the following result.

Java Collection Tutorial - ArrayList Example

Example

Example 2

Example 3

Example 4

Constructor

Method