How can I convert a Two D string array to One D string array?

Question

I have a two dimensional string array:

String myTwoD[][] = {{"Apple", "Banana"}, {"Pork", "Beef"}, {"red", 
"green","blue","yellow"}};

How do I convert this to a one dimensional string array as follows in JAVA:

OneD[]={"Apple", "Banana","Pork", "Beef","red", "green","blue","yellow"};

Can ArrayUtils be used for this?

Here is the code for my array, I am trying to store all values in a multipage table column to an array for sorting

for (i=0;i<pagecount; i++)
  {
  for (j=0;j<columncount;j++)
   {
    array[i][j]= t.getcolumnname().get(j).getText();
   }
  }

`Arrays.stream(myTwoD).flatMap(Arrays::stream).toArray(String[]::new)` — shmosel, Nov 02 '18 at 03:59

AsthaUndefined · Answer 1 · 2018-11-02T04:46:42.847

The simplest way I found out is using stream.

String myTwoD[][] = { { "Apple", "Banana" }, { "Pork", "Beef" }, { "red", "green", "blue", "yellow" } };
List<String[]> list = Arrays.asList(myTwoD);

list.stream().flatMap(num -> Stream.of(num)).forEach(System.out::println);

To store the result into a 1D array. Do this:

String arr[] = list.stream().flatMap(num -> Stream.of(num)).toArray(String[]::new);

for (String s : arr) {
   System.out.println("Array is = " + s);
}

PradyumanDixit · Accepted Answer · 2018-11-02T04:37:20.400

1

There are numerous ways of how you can do it, one way can be first storing the contents of your 2D array to a list and then using it to store the elements in your new 1D array.

In code it looks something like this:

//arr being your old array

    ArrayList<String> list = new ArrayList<String>();

    for (int i = 0; i < arr.length; i++) {
        for (int j = 0; j < arr[i].length; j++) {  
            list.add(arr[i][j]); 
        }
    }

    // now you need to add it to new array


    String[] newArray = new String[list.size()];
    for (int i = 0; i < newArray.length; i++) {
        newArray[i] = list.get(i);
    }

edited Nov 02 '18 at 04:37

answered Nov 02 '18 at 04:01

PradyumanDixit

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I tried it but didn't work. Will this work for string? @PradyumanDixit – SUPARNA SOMAN Nov 02 '18 at 04:03
@SUPARNASOMAN try the updated code – PradyumanDixit Nov 02 '18 at 04:03
It is showing null values in the array now @PradyumanDixit – SUPARNA SOMAN Nov 02 '18 at 04:25
Which array is showing null values? `newArray` must be having the values of your previous array. – PradyumanDixit Nov 02 '18 at 04:34
Can you show the exact code you're using for this, right now, because this code is and should be working. I can look into your code and tell what may have gone wrong. – PradyumanDixit Nov 02 '18 at 04:38
Hi I have updated the code, I am trying to store all the values of one column from a multipage table to an array – SUPARNA SOMAN Nov 02 '18 at 04:59
Let us [continue this discussion in chat](https://chat.stackoverflow.com/rooms/182979/discussion-between-pradyumandixit-and-suparna-soman). – PradyumanDixit Nov 02 '18 at 05:00
No worries, glad to help :) – PradyumanDixit Nov 02 '18 at 06:30
If you found the answer useful consider upvoting it and marking it as correct, I'd appreciate that. Cheers! :) – PradyumanDixit Nov 02 '18 at 06:31

score 0 · Answer 3 · answered Nov 02 '18 at 04:30

try this.

String myTwoD[][] = {{"Apple", "Banana"}, {"Pork", "Beef"},{"red", "green","blue","yellow"}};

    List<String> lt = new ArrayList<String>();

    for (String[] oneDArray : myTwoD) { //loop throug rows only
        lt.addAll(Arrays.asList(oneDArray));
    }

    String[] oneDArray =(String[])lt.toArray(new String[0]); //conversion of list to array      
    System.out.println(Arrays.toString(oneDArray)); //code for printing array

How can I convert a Two D string array to One D string array?

3 Answers3