In Java, you may encounter situations where you need to shift the elements of an array to the left by a given number of positions. This can be useful in various scenarios, such as rotating an array or implementing a queue with a fixed size.

Approach

One way to shift the elements of an array to the left is by using a temporary variable and a loop. Here’s a step-by-step approach to accomplish this task:

1. Store the first element of the array in a temporary variable.
2. Shift all the elements one position to the left by assigning the value of the subsequent element to its previous index.
3. Place the temporary variable in the last index of the array.
4. Repeat steps 1 to 3 for the desired number of positions to shift.

Example

Let’s say we have an array numbers containing [1, 2, 3, 4, 5], and we want to shift its elements two positions to the left. We can achieve this using the following code:

public class ArrayShiftExample {
    public static void shiftLeft(int[] array, int positions) {
        for (int i = 0; i < positions; i++) {
            int temp = array[0];
            for (int j = 0; j < array.length - 1; j++) {
                array[j] = array[j + 1];
            }
            array[array.length - 1] = temp;
        }
    }
    
    public static void main(String[] args) {
        int[] numbers = {1, 2, 3, 4, 5};
        int positionsToShift = 2;
        shiftLeft(numbers, positionsToShift);
        System.out.println(Arrays.toString(numbers));  # [3, 4, 5, 1, 2]
    }
}

In this example, the shiftLeft method takes an array and the number of positions to shift as parameters. It uses nested loops to shift the elements to the left and then prints the resulting array [3, 4, 5, 1, 2].

Conclusion

Shifting elements of a Java array to the left can be achieved by using a temporary variable and a loop to iterate through the array. This approach allows you to perform various operations, such as rotating an array or implementing a queue with a fixed size. By understanding the process and using the provided code example, you can easily apply this technique in your Java projects.