Question

How to reverse one dimensional int array in Java

Answer 1

package javaapplication1;

public class JavaApplication1 {

    public static void main(String[] args) 
    {
        int arr[] = new int[] {1, 2, 3, 4, 5, 6, 7};
        int tmp;
        
        for (int i = 0, j = arr.length - 1; i < arr.length / 2; i++, j--)
        {
            tmp = arr[i];
            arr[i] = arr[j];
            arr[j] = tmp;
        }
        
        for (int i = 0; i < arr.length; i++)
             System.out.format("arr[%d] = %d\n", i, arr[i]);
    }
}

/*
run:

arr[0] = 7
arr[1] = 6
arr[2] = 5
arr[3] = 4
arr[4] = 3
arr[5] = 2
arr[6] = 1

*/

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Answer 2

package javaapplication1;

public class Example {
    
    public static void main(String[] args) {
               
        int arr[] = new int[] {1, 2, 3, 4, 5, 6, 7};
        int tmp;
        int arr_size = arr.length;
         
        for (int i = 0; i < arr_size / 2; i++) 
        {
            tmp = arr[i];
            arr[i] = arr[arr_size - 1 - i];
            arr[arr_size - 1 - i] = tmp;
        }
         
        for (int i = 0; i < arr_size; i++)
             System.out.format("arr[%d] = %d\n", i, arr[i]);
    }
}
   
   
/*
run:

arr[0] = 7
arr[1] = 6
arr[2] = 5
arr[3] = 4
arr[4] = 3
arr[5] = 2
arr[6] = 1
    
*/

 

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