如何将字符串的二维数组转换为 int 类型之一？

Question

How can I convert a double array of type String to a double array of type int?

    @PostMapping("/hole/coordinate")
    @ResponseBody
    public String saveCoordinate(@RequestBody Map<String, Object> params) {
        System.out.println("params = " + params);
        System.out.println("params = " + params.get("coordinate"));
        
        return "success";
    }

System.out.println(params.get("coordinate")); store [[445, 292], [585, 331], [612, 223], [205, 532]] There are m 2 elements of the double array. ex) [a,b],[c,d].....m At this time, I want to receive the result in the data type of int[][], not String.

I was wondering how can I convert from String to int[][].

I tried like below

int[] arr= Stream.of(str.replaceAll("[\\[\\]\\, ]", "").split("")).mapToInt(Integer::parseInt).toArray();
for (int i : arr) {
    System.out.println("i = " + i);
}

but it give me

4
4
5
2
9
2
...

Best Regards!

Answer 1

You could parse it manually, as done in other answers, but since you are using spring , you should use the tools it offers you.

Spring uses jackson's ObjectMapper for serialization and deserialization by default. A bean of this type is preconfigured for you, you can autowire it in your controller method and use it. Then the entire parsing is this:

int[][] parsedCoordinates = objectMapper.readValue(coordinates, int[][].class);

And your controller method looks like this:

@PostMapping("/hole/coordinate")
@ResponseBody
public String saveCoordinate(@RequestBody Map<String, Object> params, ObjectMapper objectMapper) {
    System.out.println("params = " + params);
    System.out.println("params = " + params.get("coordinate"));
    //get string from your params
    String coordinates = "[[445, 292], [585, 331], [612, 223], [205, 532]]";
    int[][] parsedCoordinates;
    try {
        parsedCoordinates = objectMapper.readValue(coordinates, int[][].class);
    } catch (JsonProcessingException exc) {
        //that's a bad way to handle error, but it's an example
        //you might return error message like - invalid coordinate format
        //or whatever you need
        exc.printStackTrace();
        throw new RuntimeException(exc);
    }
    //printing parsed result to check it
    for (int i = 0; i < parsedCoordinates.length; i++) {
        int[] inner = parsedCoordinates[i];
        for (int j = 0; j < inner.length; j++) {
            System.out.printf("pos %d-%d, value %d%n", i, j, parsedCoordinates[i][j]);
        }
    }
    return "success";
}

Answer 2

    Try this. It creates a matrix of coordinates.

    String str = "[[445, 292], [585, 331], [612, 223], [205, 532]]";
    List<String> numbers = List.of(str.split(",| |\\[|\\]"));
    List<String> onlyNumbers = numbers.stream()
                                      .filter(number -> !number.equals("") && !number.equals(" "))
                                      .toList();
    Integer[][] coordinates = new Integer[onlyNumbers.size()][2];
    int counter = 0;
    for(int i=0; i < onlyNumbers.size() - 1; i+=2){
        coordinates[counter][0] = Integer.valueOf(onlyNumbers.get(i));
        coordinates[counter][1] = Integer.valueOf(onlyNumbers.get(i+1));
        counter++;
    }

Answer 3

You can try the below code if you are trying to convert String to int[]

import java.util.stream.*;
public class MyClass {
    public static void main(String args[]) {
      String str = "[[445, 292], [585, 331], [612, 223], [205, 532]]";
      int[] arr= Stream.of(str.replaceAll("[\\[\\]\\ ]", "").split(",")).mapToInt(Integer::parseInt).toArray();
        for (int i : arr) {
            System.out.println("i = " + i);
        }
    }
}

It prints below values as output:

i = 445
i = 292
i = 585
i = 331
i = 612
i = 223
i = 205
i = 532