Java：动态调整二维数组中的列的大小

Question

How can I size my columns dynamically to support a possible ragged array?

int[][] x;
x = new int[3][] //makes 3 rows
col = 1;
for( int i = 0; i < x.length; i++){
  x = new int[i][col]
  col++;  }

Would the above code assign each col length?

Thank you in advance for any help.

Answer 1

since you are re-assigning x , what you are doing is creating the entire 2D array each loop, which is wrong.

You need to do inside your loop:

x[i] = new int[col];

Answer 2

// create the single reference
int[][] x;

// create the array of references 
x = new int[3][] //makes 3 rows

int col = 1;
for( int i = 0; i < x.length; i++){
    // this create the second level of arrays // answer
    x[i] = new int[col];
    col++;  
}

More on 2D Arrays. - https://www.willamette.edu/~gorr/classes/cs231/lectures/chapter9/arrays2d.htm