3 Ways to Combining Array in Java

In the vast world of Java programming, arrays stand as a fundamental data structure, often employed in various applications. Whether you're a seasoned developer or just starting out, there's a good chance you've come across the need to combine arrays. This article delves deep into the art of array concatenation in Java, offering insights, best practices, and hands-on examples.

Understanding the Basics of Arrays in Java

Arrays in Java are powerful data structures that can store multiple values of the same type. They can be of primitive data types, such as int, float, or char, or they can be arrays of objects, like String or custom objects.

Methods to Combine Arrays in Java

1. Utilizing the Apache Commons Library

Apache Commons, a well-respected library in the Java community, offers a plethora of utility methods, making developers' lives easier. One such utility is the ArrayUtils.addAll() method, which seamlessly combines arrays.

import org.apache.commons.lang.ArrayUtils;

int[] firstArray = {1, 2, 3, 4};
int[] secondArray = {5, 6, 7, 8};
int[] combinedArray = ArrayUtils.addAll(firstArray, secondArray);

2. Leveraging Google’s Guava Library

Another robust library, Guava, previously known as Google Collections, provides the ObjectArrays.concat() method for array concatenation.

import com.google.common.collect.ObjectArrays;

String[] firstStringArray = {"a", "b", "c"};
String[] secondStringArray = {"d", "e"};
String[] combinedStringArray = ObjectArrays.concat(firstStringArray, secondStringArray, String.class);

3. The Native Java Approach

For those who prefer sticking to core Java without external libraries, the System.arrayCopy() method comes to the rescue.

public static int[] concatenateArrays(int[] first, int[] second) {
    int[] result = new int[first.length + second.length];
    System.arraycopy(first, 0, result, 0, first.length);
    System.arraycopy(second, 0, result, first.length, second.length);
    return result;
}

Key Takeaways

• Combining arrays is a common operation in Java, and multiple methods can achieve this.
• External libraries like Apache Commons and Guava offer straightforward methods for array concatenation.
• The native Java approach, using System.arrayCopy(), is efficient and doesn't require any external dependencies.