Programming Tutorials

Iterate a List in Java

By: Dorris in Java Tutorials on 2010-12-27  

This tutorial demonstrates the use of ArrayList, Iterator and a List. There are many ways to iterate a list of objects in Java. This sample program shows you the different ways of iterating through a list in Java.

In java a list object can be iterated in following ways:

• Using Iterator class
• With the help of for loop
• With the help of while loop
• Java 5 for-each loop

Following example code shows how to iterate a list object:

import java.util.List;
import java.util.ArrayList;
import java.util.Iterator;

public class IterateAList {
    public static void main(String[] args) {
        List arrJavaTechnologies = new ArrayList<>();

        arrJavaTechnologies.add("JSP");
        arrJavaTechnologies.add("Servlets");
        arrJavaTechnologies.add("EJB");
        arrJavaTechnologies.add("JDBC");
        arrJavaTechnologies.add("JPA");
        arrJavaTechnologies.add("JSF");

        // Iterate with the help of Iterator class
        System.out.println("Iterating with the help of Iterator class");
        Iterator iterator = arrJavaTechnologies.iterator();
        while (iterator.hasNext()) {
            System.out.println(iterator.next());
        }

        // Iterate with the help of for loop
        System.out.println("Iterating with the help of for loop");
        for (int i = 0; i < arrJavaTechnologies.size(); i++) {
            System.out.println(arrJavaTechnologies.get(i));
        }

        // Iterate with the help of while loop
        System.out.println("Iterating with the help of while loop");
        int j = 0;
        while (j < arrJavaTechnologies.size()) {
            System.out.println(arrJavaTechnologies.get(j));
            j++;
        }

        // Iterate with the help of Java 5 for-each loop
        System.out.println("Iterate with the help of Java 5 for-each loop");
        for (String element : arrJavaTechnologies) {
            System.out.println(element);
        }
    }
}