How to Get Subarray in Java?
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()
TheArrays.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:TheIntStream.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.
