Java 程序：反转数组

原文： https://beginnersbook.com/2017/09/java-program-to-reverse-the-array/

该程序反转数组。例如，如果用户输入数组元素为1,2,3,4,5，那么程序将反转数组，数组元素将为5,4,3,2,1。要理解这个程序，你应该有以下 Java 编程主题的知识：

1. Java 中的数组
2. Java For循环
3. Java While循环

示例：反转数组

import java.util.Scanner;
public class Example
{
   public static void main(String args[])
   {
    int counter, i=0, j=0, temp;
    int number[] = new int[100];
    Scanner scanner = new Scanner(System.in);
    System.out.print("How many elements you want to enter: ");
    counter = scanner.nextInt();
    /* This loop stores all the elements that we enter in an 
     * the array number. First element is at number[0], second at 
     * number[1] and so on
     */
    for(i=0; i<counter; i++)
    {
        System.out.print("Enter Array Element"+(i+1)+": ");
        number[i] = scanner.nextInt();
    }
    /* Here we are writing the logic to swap first element with
     * last element, second last element with second element and
     * so on. On the first iteration of while loop i is the index 
     * of first element and j is the index of last. On the second
     * iteration i is the index of second and j is the index of 
     * second last.
     */
    j = i - 1;     
    i = 0;         
    scanner.close();
    while(i<j)
    {
         temp = number[i];
       number[i] = number[j];
       number[j] = temp;
       i++;
       j--;
    }
    System.out.print("Reversed array: ");
    for(i=0; i<counter; i++)
    {
       System.out.print(number[i]+ "  ");
    }       
   }
}

输出：

How many elements you want to enter: 5
Enter Array Element1: 11
Enter Array Element2: 22
Enter Array Element3: 33
Enter Array Element4: 44
Enter Array Element5: 55
Reversed array: 55  44  33  22  11

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