Java converting string to 2d int array-CodePudding

I have string represention of 2d array i like to convert it to 2d int array The method i found is cumbersome , what is the best way to do it ? This is my method :

private static int[][] convertMatrix() {

        String mat = "[0, 10, 0, 5, 4],\n"  
                "[1, 3, 10, 2, 8],\n"  
                "[1, 8, 1, 6, 3],\n"  
                "[4, 10, 2, 3, 5],\n"  
                "[9, 0, 9, 1, 0]";

        mat = mat.trim().replaceAll("\\s ","").replaceAll("(?:\\n|\\r)", "");;
        String[] matarr = mat.split("],");
        int[][] matrix = new int[5][5];
        for(int i = 0;i<matarr.length-1;i  ) {
            String lineofnumbers = matarr[i].replace("[","");
            String[] lineofnumArr = lineofnumbers.split(",");
            int[] tmp = new int[lineofnumArr.length];
            for(int ii = 0 ; ii < lineofnumArr.length;ii  )
            {
                tmp[ii] = Integer.parseInt(lineofnumArr[ii]);
                //tmp[ii] = ;
            }
            matrix[i] = tmp;
        }
 
        return matrix;
    }

i have only java 1.8 support how can i convert it to version with streams
and version without streams magic ?

CodePudding user response：

One way to do it with using the Streams API is like so:

int[][] ints = Arrays.stream(mat.split(",\n"))      // split rows
        .map(s -> s.substring(1, s.length() - 1))   // remove '[' and ']'
        .map(s -> s.split(", *"))                   // split cols of row
        .map(arr -> Arrays.stream(arr)              // map String array to int array
                .mapToInt(Integer::parseInt)
                .toArray()
        )
        .toArray(int[][]::new);
System.out.println(Arrays.deepToString(ints));

Output:

[[0, 10, 0, 5, 4], [1, 3, 10, 2, 8], [1, 8, 1, 6, 3], [4, 10, 2, 3, 5], [9, 0, 9, 1, 0]]

If you don't want to use streams, a good way to start is to replace the Arrays.stream calls with for loops.

CodePudding user response：

Split your input at each comma followed by a new line ,\n and stream over the resulting array, remove [ and ], map to stream by spliting at comma and space \\s*,\\s* and streaming over the resulting array, parse the elements of the stream to int and collect each sub stream to array, and finally collect the arrays to a 2d-array.

int[][] result = Arrays.stream(mat.split(",\n"))
                       .map(str -> str.replaceAll("\\[|\\]",""))
                       .map(str -> Arrays.stream(str.split("\\s*,\\s*")))
                       .map(arr -> arr.mapToInt(Integer::parseInt).toArray())
                       .toArray(int[][]::new);