Shift Array Elements to the Left in Java

Shifting elements in an array is a common problem in programming, often used in tasks like data processing, cyclic rotations, or simulations. In this article, we'll learn how to shift elements of an array to the left in Java,we will be using the Array class of java.util package.

What Is Left Shifting in an Array?

Left shifting means moving all elements of an array to the left by a specified number of positions. For instance:

• Original Array: {1, 2, 3, 4, 5}
  
• After 1 Left Shift: {2, 3, 4, 5, 1}
  
• After 2 Left Shifts: {3, 4, 5, 1, 2}

Java program to shift array elements to the left

Storing the first shiftCount elements in temp

System.arraycopy(array, 0, temp, 0, shiftCount);

Shift the remaining elements using arraycopy method

System.arraycopy(array, shiftCount, array, 0, n - shiftCount);

Temporary array to hold shifted elements

int[] temp = new int[shiftCount];

Place the shifted elements from temp at the end

System.arraycopy(temp, 0, array, n - shiftCount, shiftCount);

Example

Below is the code implementation to shift array elements to the left ?

import java.util.Arrays;
public class ShiftArrayLeft {
    public static void main(String[] args) {
        // Example array
        int[] array = {1, 2, 3, 4, 5};
        // Number of positions to shift
        int shiftCount = 1;
        System.out.println("Original Array: " + Arrays.toString(array));
        // Perform left shift
        leftShift(array, shiftCount);
        System.out.println("Array after left shift: " + Arrays.toString(array));
    }
    // Method to shift array elements to the left
    public static void leftShift(int[] array, int shiftCount) {
        int n = array.length;
        // Reduce shift count if it's larger than array size
        shiftCount %= n;
        // Temporary array to hold shifted elements
        int[] temp = new int[shiftCount];
        // Store the first 'shiftCount' elements in temp
        System.arraycopy(array, 0, temp, 0, shiftCount);

        // Shift the remaining elements
        System.arraycopy(array, shiftCount, array, 0, n - shiftCount);
        // Place the shifted elements from temp at the end
        System.arraycopy(temp, 0, array, n - shiftCount, shiftCount);
    }
}

Output

Original Array: [1, 2, 3, 4, 5]
Array after left shift: [2, 3, 4, 5, 1]

Conclusion

Shifting array elements to the left in Java is an essential operation, often required in algorithms and data manipulation tasks. The method shown above is efficient, leveraging Java's System.arraycopy() for faster copying of elements. By following the reusable approach, you can handle various scenarios of array shifting with ease.