In Java, subarrays are the contiguous portion of an array. Extracting subarrays in Java is common when working with data that needs slicing or partitioning. Java does not have a direct method to create subarrays, we can extract subarrays using simple techniques like built-in methods or manual loops.
Example: The simplest way to get a subarray is by using a manual loop. This approach is straightforward and gives us full control over the array slicing.
// Java Program to get a Subarray in Java
// Using a Simple Loop
public class SubArray {
public static void main(String[] args) {
int[] arr = {1, 2, 3, 4, 5};
// Define the range for the subarray
int a = 1; // Start index (inclusive)
int b = 4; // End index (exclusive)
// Create the subarray using a loop
int[] sub = new int[b - a];
for (int i = a; i < b; i++) {
sub[i - a] = arr[i];
}
System.out.print("");
for (int n : sub) {
System.out.print(n + " ");
}
}
}
Output
2 3 4
Other Methods to Get Sub Array
1. Using Arrays.copyOfRange()
The Arrays.copyOfRange() is the easiest and efficient method to get a subarray. It eliminates the need for a manual loop. It is useful when we want a quick and clean way to extract a subarray without need to think about index management.
// Java Program to Get a Subarray
// Using Arrays.copyOfRange() method
import java.util.Arrays;
public class SubArray {
public static void main(String[] args) {
int[] arr = {1, 2, 3, 4, 5};
// Extract subarray using copyOfRange
// From index 1 to 4 (exclusive)
int[] sub = Arrays.copyOfRange(arr, 1, 4);
System.out.println("" + Arrays.toString(sub));
}
}
Output
[2, 3, 4]
2. Using Java Streams (Java 8+)
In Java 8, Streams provide a modern, functional approach for extracting subarrays. This method is useful when additional processing is needed.
// Java Program to Get a Subarray
// Using Java Streams
import java.util.Arrays;
import java.util.stream.IntStream;
public class SubArray {
public static void main(String[] args) {
int[] arr = {1, 2, 3, 4, 5};
// Extract subarray using streams
int[] sub = IntStream.range(1, 4) // From index 1 to 4 (exclusive)
.map(i -> arr[i])
.toArray();
System.out.println("" + Arrays.toString(sub));
}
}
Output
[2, 3, 4]
Explanation: The IntStream.range(from, to) generates a stream of indices. The .map(i -> array[i]) maps each index to the corresponding array element. The .toArray() method converts the stream back to an array.