In this quick article, we will discuss different ways to iterate over a List in Java. Iterating or looping a List is a common task in a day to day project work so in this article, I would like to demonstrate different ways to iterate over a List using JDK 7 and 8.
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Java Program to iterate over a List in Java
Note that I have used lambda expression and method reference features in this program so you have to use JDK 8 or later to run this program. Please refer the comments in below program are self-descriptive.
package net.javaguides.collections;
import java.util.Arrays;
import java.util.Iterator;
import java.util.List;
/**
*
* Java program to demonstrate different ways to Iterate over an ArrayList in Java
* @author Ramesh Fadatare
*
*/
public class DifferentWaysListIterateProgram {
public static void main(String...args) {
List < String > courses = Arrays.asList("C", "C++", "Core Java", "J2EE", "Spring", "Hibernate", "Python");
// Basic loop
for (int i = 0; i < courses.size(); i++) {
String course = courses.get(i);
printCourse(course);
}
// Enhanced for loop
for (String course: courses) {
printCourse(course);
}
// Basic loop with iterator
for (Iterator < String > it = courses.iterator(); it.hasNext();) {
String course = it.next();
printCourse(course);
}
// Iterator with while loop
Iterator < String > it = courses.iterator();
while (it.hasNext()) {
String course = it.next();
printCourse(course);
}
// JDK 8 streaming example lambda expression
courses.stream().forEach(course - > printCourse(course));
// JDK 8 streaming example method reference
courses.stream().forEach(DifferentWaysListIterateProgram::printCourse);
// JDK 8 for each with lambda
courses.forEach(course - > printCourse(course));
// JDK 8 for each
courses.forEach(DifferentWaysListIterateProgram::printCourse);
}
// common method to print course
private static void printCourse(String course) {
System.out.println("course name :: " + course);
}
}
Output:
course name :: C
course name :: C++
course name :: Core Java
course name :: J2EE
course name :: Spring
course name :: Hibernate
course name :: Python
course name :: C
course name :: C++
course name :: Core Java
course name :: J2EE
course name :: Spring
course name :: Hibernate
course name :: Python
course name :: C
course name :: C++
course name :: Core Java
course name :: J2EE
course name :: Spring
course name :: Hibernate
course name :: Python
course name :: C
course name :: C++
course name :: Core Java
course name :: J2EE
course name :: Spring
course name :: Hibernate
course name :: Python
course name :: C
course name :: C++
course name :: Core Java
course name :: J2EE
course name :: Spring
course name :: Hibernate
course name :: Python
course name :: C
course name :: C++
course name :: Core Java
course name :: J2EE
course name :: Spring
course name :: Hibernate
course name :: Python
course name :: C
course name :: C++
course name :: Core Java
course name :: J2EE
course name :: Spring
course name :: Hibernate
course name :: Python
course name :: C
course name :: C++
course name :: Core Java
course name :: J2EE
course name :: Spring
course name :: Hibernate
course name :: Python
Please leave a comment if you have any other way to iterate over a Set so that I will add to this article.
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