For-Each Loop in Java

December 7, 2017March 28, 2018 Vertex Academy for each loop in Java, for each loop java

Hi! This is one of the articles from our Java Tutorial for Beginners.

Have you ever used loops in programming?

If the answer is "No," then start by reading this article: "What are Loops in Java? And What are the Different Types of Loops?"
If the answer is "Yes," then read the article below, which is about the "for-each" loop.

The "For-Each" Loop:

is a version of the "for" loop.
is used to check whether each element in an array or in a collection matches some condition.
appeared for the first time in JDK5

Let's examine how the syntax of the "For" loop and the syntax of the "For-Each" loop appear.

1. The Syntax of the "For" Loop

for (initialization; condition; iteration) {
 
// the action to be performed
 
}

for (initialization; condition; iteration) {

// the action to be performed

}

2. The Syntax of the "For-Each" Loop

for (the type item and name of the variable: the name of the array/collection) {
 
// the action to be performed
 
}

for (the type item and name of the variable: the name of the array/collection) {

// the action to be performed

}

Note: In the "For-Each" loop, the type item must match the type item of the array.

In order to understand how the two loops differ, let's solve the same task two different ways:

With the help of the "for" loop
With the help of the "for-each" loop

Task No. 1

It's necessary to check whether each element in the array matches the condition, and then to display the ones that match the condition in the console.

1. "For" Loop Solution:

class Test {
 
	public static void main(String[] args) {
           int[] array = {51,136, 387};
 
           for (int i = 0; i < array.length; i++) {
           System.out.println(array[i]);
           }
	}
}

class Test {

public static void main(String[] args) {

int[] array = {51,136, 387};

for (int i = 0; i < array.length; i++) {

System.out.println(array[i]);

}

If you run this code, you will see the following in the console:

51
136
387

2."For-Each" Loop Solution:

class Test {
 
	public static void main(String[] args) {
           int[] array = {51,136,387};
 
           for (int i:array) {
           System.out.println(i);
           }
	}
}

class Test {

public static void main(String[] args) {

int[] array = {51,136,387};

for (int i:array) {

System.out.println(i);

}

If you run this code, you will see the following in the console:

51
136
387

As you see, the "for-each" loop does not require you to manually change the variable. The loop automatically executes this job.

Note: In the "For-Each" loop, the type item must match the type item of the array.

In the previous example, our array has the "int" type item. That's why we wrote the following:

 for (int i:array)

1	for (int i:array)

Task No. 2

It's necessary to check whether each element in the array matches the condition.

1. "For"Loop Solution:

class Test {
 
	public static void main(String[] args) {
 
	  ArrayList<Integer> list = new ArrayList<>();
          list.add(51);
          list.add(136);
          list.add(387);
 
          for (int i = 0; i < list.size(); i++) {
            System.out.println(list.get(i));
          }
	}
}

class Test {

public static void main(String[] args) {

ArrayList<Integer> list = new ArrayList<>();

list.add(51);

list.add(136);

list.add(387);

for (int i = 0; i < list.size(); i++) {

System.out.println(list.get(i));

}

If you run this code, you will see the following in the console:

51
136
387

2. "For-Each" Loop Solution:

class Test {
 
	public static void main(String[] args) {
 
	  ArrayList list = new ArrayList<>();
          list.add(51);
          list.add(136);
          list.add(387);
 
          for (Integer i:list) {
            System.out.println(i);
          }
	}
}

class Test {

public static void main(String[] args) {

ArrayList list = new ArrayList<>();

list.add(51);

list.add(136);

list.add(387);

for (Integer i:list) {

System.out.println(i);

}

If you run this code, you will see the following in the console:

51
136
387

As you see, the "for-each" loop does not require you to manually change the variable. The loop automatically executes this job.

So, the "for-each" loop is very convenient when it's necessary to:

display all the values of elements of an array/collection in the console
or copy all the values of elements in one array/collection and put them in a different array/collection.

You can find more articles in our Java Tutorial for Beginners.