Java Array Reverse

Question

This is my first question here. So The thing is...I would like to understand, how could I reverse an array, that contains objects, without using Array.java.utils and a Temporary array.

    public void reverse() {

    Ball [] ballsTemp = new Ball[balls.length];
    for (int i = 0; i < balls.length / 2; i++) {
        ballstemp[i] = balls[i];
        balls[i] = balls[balls.length -1 - i];
        balls[balls.length -1 - i] = ballstemp[i];
    }
}

So this is not what I want ^

My bad sorry. it was mean to be balls. So we are working with a balls[ ] ; — Bruno L
– Bruno L, Commented Oct 27, 2015 at 18:56
You don't need a temporary array, but you do need a temporary variable. With an integer array it can be done without one, due to bit-trickery, but you can't do that with objects. — Kayaman
– Kayaman, Commented Oct 27, 2015 at 18:59

gidim · Accepted Answer · 2015-10-27 19:00:53Z

2

Use a temp variable instead of a temp array.

for (int i = 0; i < balls.length / 2; i++) {
    Object temp = balls[i];
    balls[i] = balls[balls.length -1 - i];
    balls[balls.length -1 - i] = temp;
}

answered Oct 27, 2015 at 19:00

gidim

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1 Comment

Bruno L Over a year ago

I think, You helped a lot! Ty. That easy.

chrisA · Accepted Answer · 2015-10-27 19:14:54Z

1

Use a Stack instead, here is a very simple example:

  Integer[] intArray = new Integer[5];
  intArray[0] = 3;
  intArray[1] = 6;
  intArray[2] = 9;
  intArray[3] = 12;
  intArray[4] = 15;

  Stack<Integer> intStack = new Stack<Integer>();
  for(int i = 0; i < intArray.length; i++) {
      intStack.push(intArray[i]);
  }

  for(int i = 0; i < intArray.length; i++) {
      intArray[i] = intStack.pop();
  }

answered Oct 27, 2015 at 19:14

chrisA

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Comments

Gaël J · Accepted Answer · 2015-10-27 19:40:13Z

1

If you don't want to use a temporary array, you could use a Stack instead.

Stack ballsTemp = new Stack();
for (int i=0; i<balls.length; i++) {
    ballsTemp.push(balls[i]);
}
for (int i=0; i<balls.length; i++) {
    balls[i] = ballsTemp.pop();
}

edited Oct 27, 2015 at 19:40

Gaël J

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answered Oct 27, 2015 at 19:08

Bethany Louise

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