How do I find specific elements or object in an array?

This example demonstrates how to find specific items in an array. We will use the org.apache.commons.lang3.ArrayUtils class. This class provides method called contains(Object[] array, Object objectToFind) method to check if an array contains the objectToFind in it.

We can also use the indexOf(Object[] array, Object objectToFind) method and the lastIndexOf(Object[] array, Object objectToFind) method to get the index of an array element where our objectToFind is located.

package org.kodejava.commons.lang;

import org.apache.commons.lang3.ArrayUtils;

public class ArrayUtilsIndexOfDemo {
    public static void main(String[] args) {
        String[] colors = { "Red", "Orange", "Yellow", "Green",
                "Blue", "Violet", "Orange", "Blue" };

        // Does the "colors" array contain the Blue color?
        boolean contains = ArrayUtils.contains(colors, "Blue");
        System.out.println("Contains Blue? " + contains);

        // Can you tell me the index of each color defined bellow?
        int indexOfYellow = ArrayUtils.indexOf(colors, "Yellow");
        System.out.println("indexOfYellow = " + indexOfYellow);

        int indexOfOrange = ArrayUtils.indexOf(colors, "Orange");
        System.out.println("indexOfOrange = " + indexOfOrange);

        int lastIndexOfOrange = ArrayUtils.lastIndexOf(colors, "Orange");
        System.out.println("lastIndexOfOrange = " + lastIndexOfOrange);
    }
}

Here are the results of the code above.

Contains Blue? true
indexOfYellow = 2
indexOfOrange = 1
lastIndexOfOrange = 6

Maven Dependencies

<dependency>
    <groupId>org.apache.commons</groupId>
    <artifactId>commons-lang3</artifactId>
    <version>3.14.0</version>
</dependency>