Handing 2D-Array from Spring boot to React

Question

I am trying to send a 2D Char-Array from my Spring-Controller to React ... it works when i use Arraylist but doesn't work with "char[ ][ ]"

so this works

@GetMapping(value = "/test")
public ArrayList<String> getTest() {

    ArrayList<String> arr = new ArrayList<String>();
    arr.add("Something");
    arr.add("Somehow");
    return arr;

and this Does not work

@SuppressWarnings("checkstyle:WhitespaceAround")
@GetMapping(value = "/newboard")
public char[][] emptyBoard(char[][] playField) {

    for (char y = 0; y < playField.length; y++) {

        for (char x = 0; x < playField[y].length; x++) {

            playField[y][x] = (' ');

        }
    }
        return playField;
}

I'm trying to use a better and more simple approach, because i don't want to change all the methods in my code... since they all uses "playField as char[][]" @AlbertoSinigaglia — Bashar Boutros
– Bashar Boutros, Commented Jun 21, 2021 at 12:50

Bashar Boutros · Accepted Answer · 2021-06-22 18:42:21Z

1

After a good research i found that it doesn't work sending primitive datatype to Frontend... this is as Answer to this question not all the situations maybe, but at least in my case that was the solution.

you have to try the following:

Either try the Refernce types =>

@GetMapping(value = "/test")
public ArrayList<String> getTest() {

ArrayList<String> arr = new ArrayList<String>();
arr.add("Something");
arr.add("Somehow");
return arr;

OR this approach (From type {Class} ) =>

 @GetMapping(value = "/test")
 public MyModel getTest() {


    MyModel myModel = new MyModel();
    myModel.setFirstName("Somthing");
    myModel.setLastName("Somehow");

    GameUpdate u = new GameUpdate();
    Player p1 = new Player();
    p1.setName("1");
    u.setPlayer1(p1);
    return myModel;
}

answered Jun 22, 2021 at 18:42

Bashar Boutros

315 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Alberto · Accepted Answer · 2021-06-21 20:47:01Z

0

You can just change the return type, and so "cast" the return object:

@SuppressWarnings("checkstyle:WhitespaceAround")
@GetMapping(value = "/newboard")
public List<List<Character>> emptyBoard(char[][] playField) {

    for (char y = 0; y < playField.length; y++) {

        for (char x = 0; x < playField[y].length; x++) {

            playField[y][x] = (' ');

        }
    }
    return Arrays.asList(playField)
                .stream()
                .map(Arrays::asList)
                .collect(Collectors.toList());
}

edited Jun 21, 2021 at 20:47

answered Jun 21, 2021 at 16:01

Alberto

13.1k3 gold badges31 silver badges72 bronze badges

4 Comments

Bashar Boutros Over a year ago

Thanks for the answer but => "List<List<Character>>" this aproach looks like the same as (Arraylist<Arraylist<char[]>>)... your solution maybe usefull but i need to change the variable (playField) in all the methods i used, and that will cause a lot of problem in my game Algorithm.

Alberto Over a year ago

@BasharBoutros no you don't need to change anything, you will need to change only the return statement on the Controller class where you are returning the matrix

Bashar Boutros Over a year ago

i got this error java: cannot find symbol symbol: method asList() location: class java.util.stream.Collectors

Alberto Over a year ago

@BasharBoutros sorry, just a typo, try now

Collectives™ on Stack Overflow

Handing 2D-Array from Spring boot to React

2 Answers 2

Comments

4 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

4 Comments

Your Answer

Sign up or log in

Post as a guest

Related