Java Foreach

Summary: in this tutorial, you will learn how to use the Java Foreach loop to iterate over elements of an array or collection.

Introduction to the Java Foreach loop

To iterate over elements of an array, you often use a for loop. For example:

double[] amounts = { 9.99, 10.25, 7.89 };

for (int i = 0; i < amounts.length; i++) {
   System.out.println(amounts[i]);
}Code language: Java (java)

In the for loop:

• First, initialize a loop variable i that represents the index of the element of the array.
• Second, access the array element by the index i, display it, and increase the loop variable i by one to advance to the next index in each iteration.
• Third, continue the loop as long as the loop variable i is less than the number of elements of the array.

The for loop works fine. But it has some issues:

• Index management: You need to manage the loop variable, which serves as the array index, yourself. If you do it incorrectly, you’ll get an exception.
• Code clutter: The for loop makes the code more cluttered, especially with complex logic within the loop body.
• Limited abstraction: The for loop exposes very low-level control over the iteration process.

To address these issues, Java 8 introduced an enhanced for loop, which is often called a Foreach loop.

Here’s the syntax of the Foreach loop:

for(dataType element: array) {
    // ...
}Code language: Java (java)

In this syntax;

• dataType specifies the data type of the element of the array.
• element is a variable that holds each element in the array during iteration.
• array is the array to be iterated.

Since Java can infer the type of the array element, you can use the var keyword to make the code more concise:

for(var element: array) {
    // ...
}Code language: Java (java)

For example, the iterate over elements of the amounts array above, you can use a Foreach loop as follows:

double[] amounts = {9.99, 10.25, 7.89};

for(var amount: amounts) {
    System.out.println(amount);
}Code language: Java (java)

Summary

• Use a Foreach loop to iterate over elements of an array or a collection to make code more concise.