CODEWITHSUNDEEP
javaarrays
coco
coco

Reputation: 95

Java arrange array

I have the following array:

{x1, null, null, null, y1, null, null, null, z1, x2, null, null, null, y2, null, null, null, z2, x3, null, null, null, y3, null, null, null, z3}

and I need to arrange it like this:

{x1, y1, z1, x2, y2, z2, x3, y3, z3}

Can you help me please? I have no idea how to start it.

Upvotes: 1

Views: 163

Answers (5)

Vinay Prajapati
Vinay Prajapati

Reputation: 7556

Best way is to rely on ready made java methods as these are created and tested properly. Data type is although not clear from the array you specified,I am considering it as String

Code:-

String []elements = new String[]{"x1", null, null, null, "y1", null, null, null, "z1", "x2", null, null, null, "y2", null, null, null, "z2", "x3", null, null, null, "y3", null, null, null, "z3"};
Set<String> set = new HashSet<String>(Arrays.asList(elements));
set.remove(null);

Upvotes: 0

Ashot Karakhanyan
Ashot Karakhanyan

Reputation: 2830

Previous answers are right, but if you need more quick copy, you can do something like the following. If your data contain chars, for exampleThis solution with work ONLY if the source array has 9*k elements i.e. 9, 18, 27,... etc. (as I understood your array is like that):

    char[] source = {'1', ' ', ' ',
            ' ', '2', ' ',
            ' ', ' ', '3',
            '4', ' ', ' ',
            ' ', '5', ' ',
            ' ', ' ', '6'};

    char[] target = new char[source.length / 3];
    int targetIndex = 0;
    for (int i = 0; i < source.length; i += 9) {
        target[targetIndex++] = source[i + 0];
        target[targetIndex++] = source[i + 4];
        target[targetIndex++] = source[i + 8];
    }

Upvotes: 0

The Guy with The Hat
The Guy with The Hat

Reputation: 11132

Here is one way to do that:

  1. Convert the array to a ArrayList using Arrays' asList method.

    Object[] objects = {new Object(), null, null, new Object(), null};
List<Object> tempList = new ArrayList(Arrays.asList(objects));

  2. Loop through tempList.

    for(int i = 0; i < tempList.size(); i++)
{

  3. remove() the element from tempList if it is null.

        if(tempList.get(i) == null)
    {
        tempList.remove(i);
        i--;
    }
}

  4. Covert tempList back to an array using ArrayList's toArray() method.

    objects = tempList.toArray();

Here is a complete working example:

import java.util.List;
import java.util.ArrayList;
import java.util.Arrays;
public class RemoveArrayNull
{
    public static void main(String[] args)
    {
        Object[] objects = new Object[] {new Object(), null, null, new Object(), null};
        objects = removeNull(objects);
        System.out.println(Arrays.toString(objects));
    }

    static Object[] removeNull(Object[] objects)
    {
        List<Object> tempList = new ArrayList(Arrays.asList(objects));
        for(int i = 0; i < tempList.size(); i++)
        {
            if(tempList.get(i) == null)
            {
                tempList.remove(i);
                i--;
            }
        }
        return tempList.toArray();
    }
}

Upvotes: 0

Miquel
Miquel

Reputation: 15675

I'm assuming by array you mean some sort of List. If so, use an iterator, I'm assuming x1 is of class Integer:

Iterator<Integer> arrayIt = arrayIt.iterator();
while(arrayIt.hasNext()){
    if(arrayIt.next() == null){
        arrayIt.remove();
    }
}

If your array is really large, it will run much faster if the array is implemented using a LinkedList rather than, say, an ArrayList

Upvotes: 1

Keppil
Keppil

Reputation: 46239

I would follow these steps:

  1. Loop through the array. Add each non-null element to a List
  2. Use the toArray() method to create a new array.

Upvotes: 5

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