Java implementation code for array flipping

1. Java provides some toolkits to realize array flipping. I won't repeat reverse here...

2. You can also assign a new array through a flashback loop, for example

private static String[] reverseArray(String[] Array) {
    String[] new_array = new String[Array.length];
    for (int i = 0; i < Array.length; i++) {
      // 反转后数组的第一个元素等于源数组的最后一个元素：
      new_array[i] = Array[Array.length - i - 1];
    }
    return new_array;
  }

3. But can the efficiency be higher, and how to flip on the same array

For example, arrays: A, B, C, D, e, F, G

Return result: G, a

Analysis: array length is 7

Corresponding to the array tag, the array starts from 0, that is, 0, 1, 2, 3, 4, 5, 6

When the length is singular, the middle bits do not need to be interchanged, that is, D (4) does not need to be interchanged, that is, 7 / 2 rounding result 3, 3 + 1 does not need to be interchanged, that is, length / 2 + 1 does not need to be interchanged

When the length is an even number, it does not need to be considered and all are exchanged

Summary: the data to be exchanged are 0 ~ (length / 2 - 1) and length / 2 ~ (length - 1)

Set the circulatory system I = 0 and the threshold value is lenth / 2 - 1. At the same time, flashback and obtain the following parameters for exchange.

public static void main(String[] args) {
		String[] num = {"1","2","3","4","5","6"};

		for (int i = 0; i <= num.length / 2 - 1; i++) {
			String temp1 = num[i];
			String temp2 = num[num.length - i - 1];
			num[i] = temp2;
			num[num.length - i - 1] = temp1;
		}
		System.out.println(Arrays.asList(num).toString());
	}

Just think of these for the time being, and hide the knowledge points. The difference between value passing and reference passing in Java....

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