java - java中反转两个输入数组

Question

如何反转此代码？我以为我正在使用正确的方法来反转这个数组，但它仍然不起作用......

我希望有人能帮助我。 tq

所以，这是我的代码:

import java.util.Scanner ;

public class ArrayYear
{
    public static void main (String[] args)
    {
       Scanner in = new Scanner(System.in);
       int[] arr = new int[3];
       int[] year = new int[3];

       //read element into array 
       for (  int i=0 ; i <= arr.length ; i++ )
       {
           arr[i] = in.nextInt() ;  // input value 

            for ( int j=0 ; j<=arr.length/2 ; j++ ){

                  int temp = arr[j];
                  arr[j] = arr[arr.length - i - 1 ];
                  arr[arr.length - i - 1 ] = temp;               
          }   

           year[i]= in.nextInt();

           System.out.println( "ID :" + arr[i] + "("+ year[i] +")" ) ;
       }      
    }
}

注意:需要反转的数组只是第一个数组arr[i]

Answer 1

您必须先填充数组，然后反转它，并且循环应达到 i<=arr.length-1 .反转数组代码将是

public static int[] reverseArray(int a[]) {

    int b[] = new int[a.length];
    int index = 0;
    for (int i = a.length - 1; i >= 0; i--)
    b[index++] = a[i];

    return b;
}
public static void main(String[] args) throws java.lang.Exception {
    Scanner sc = new Scanner(System. in );
    int c[] = new int[5];
    int index = 0;
    while (sc.hasNextLine()) {
        c[index++] = Integer.parseInt(sc.nextLine().trim());
    }
    System.out.println("Before Reverse " + Arrays.toString(c));
    System.out.println("After Reverse " + Arrays.toString(reverseArray(c)));
}

输入

1
2
3
4
5

输出

Before Reverse [1, 2, 3, 4, 5]
After Reverse [5, 4, 3, 2, 1]

Demo