2 dimensional array

public class Solution {
    public int[][] GenerateMatrix(int n) {
        int[][] matrix = new int[n][];
        for(int i = 0; i < n; i++){
            matrix[i] = new int[n];
        }
        
        int i = 1;
        int rowStart = 0;
        int rowEnd = n-1;
        int colStart = 0;
        int colEnd = n-1;
        
        while(rowStart <= rowEnd && colStart <= colEnd){
            for(int j = colStart; j <= colEnd; j++){
                matrix[rowStart][j] = i++;
            }
            rowStart++;
            
            for(int j = rowStart; j <= rowEnd; j++){
                matrix[j][colEnd] = i++;
            }
            colEnd--;
            
            if(rowStart <= rowEnd){
                for(int j = colEnd; j >= colStart; j--){
                    matrix[rowEnd][j] = i++;