How to Check If an Array Contains a Specific Value in Java?

How can I check if a specific value exists in a String array in Java?

public static final String[] VALUES = new String[] {"AB", "BC", "CD", "AE"};
String s = "AB";

In Java, checking if an array contains a specific value is a common task that can be accomplished using several methods. This guide will detail the most effective ways to perform this check, including the use of loops and built-in methods.

// Method 1: Using a loop
public static boolean containsValue(String[] array, String value) {
    for (String element : array) {
        if (element.equals(value)) {
            return true;
        }
    }
    return false;
}

// Method 2: Using Arrays.asList()
import java.util.Arrays;

public static boolean containsValue(String[] array, String value) {
    return Arrays.asList(array).contains(value);
}

Causes

• The value being searched for may not exist in the array.
• The array may be null or uninitialized, causing a NullPointerException if accessed.

Solutions

• Use a simple loop to iterate through the array and compare each element with the target value.
• Utilize Java's built-in Arrays utility class and its method `Arrays.asList()` combined with `contains()` to simplify the process.

Mistake: Using `==` to compare String values instead of `.equals()` method.

Solution: Use the `.equals()` method to compare actual content of String values.

Mistake: Not checking if the array is null before accessing it.

Solution: Add a null check for the array before processing to avoid NullPointerException.