ArrayList forEach() Method in Java (original) (raw)

Last Updated : 10 Dec, 2024

In Java, the **ArrayList.forEach() method is used to iterate over each element of an ArrayList and perform certain operations for each element in ArrayList.

*Example 1: Here, we will use the forEach() method **to print all elements of an ArrayList of **Strings_**.*_

Java `

// Java program to demonstrate the use of forEach() // with an ArrayList of Strings import java.util.ArrayList;

public class GFG { public static void main(String[] args) {

    // Create an ArrayList of Strings
    ArrayList<String> s = new ArrayList<>();
    s.add("Cherry");
    s.add("Blueberry");
    s.add("Strawberry");

    // Use forEach() to print each fruit
    s.forEach(System.out::println);
}

}

`

Output

Cherry Blueberry Strawberry

**Explanation: In the above example, we use the forEach() method with a method reference (System.out::println) to print each element in the ArrayList.

**Syntax of ArrayList.forEach() Method

public void forEach(Consumer<? super E> action)

**Parameter: action: A functional interface "Consumer" that specifies the action to be performed for each element in the ArrayList. It accepts a single parameter and does not return any value.

**Exception: This method throws NullPointerException if the specified action is null.

Other Examples of forEach() Method

**Example 2: Here, we will use the **forEach() method with a lambda expression to print the square of each element in an ArrayList of Integers.

Java `

// Java program to demonstrate // custom actions using forEach() import java.util.ArrayList;

public class GFG { public static void main(String[] args) {

    // Create an ArrayList of Integers
    ArrayList<Integer> n = new ArrayList<>();
    n.add(2);
    n.add(3);
    n.add(4);

    // Use forEach() to print the 
    // square of each number
    n.forEach(num -> System.out.println(num * num));
}

}

`

**Example 3: Here, we will use the **forEach() method with a **conditional statement to filter and print eligible elements of an ArrayList of Integers.

Java `

// Java program to demonstrate // conditional actions using forEach() import java.util.ArrayList;

public class GFG { public static void main(String[] args) {

    // Create an ArrayList of Integers
    ArrayList<Integer> a = new ArrayList<>();
    a.add(24);
    a.add(18);
    a.add(10);

    // Use forEach() to print 
    // ages that are 18 or above
    a.forEach(age -> {
        if (age >= 18) {
            System.out.println("Eligible age: " + age);
        }
    });
}

}

`

Output

Eligible age: 24 Eligible age: 18

**Explanation: In the above example, we use the **forEach() method with a lambda expression and **conditional logic to filter and print elements based on a condition.