Iterate through 2 dimensional array

问题:

I have a "connect four board" which I simulate with a 2d array (array[x][y] x=x coordinate, y = y coordinate). I have to use "System.out.println", so I have to iterate through the rows.

I need a way to iterate this way [0,0] [1,0] [2,0] [3,0] [0,1] [1,1] [2,1] etc

If i use the normal procedure:

for (int i = 0; i<array.length; i++){
     for (int j = 0; j<array[i].length; j++){
        string += array[i][j];
     } System.out.println(string)

}

it doesnt work because it iterates this way [0,0] [0,1] [0,2] [0,3] etc

The normal procedure stays in x and increments y until the end of the column, but i need to say in y and increment x until the end of the row.

回答1:

Consider it as an array of arrays and this will work for sure.

int mat[][] = { {10, 20, 30, 40, 50, 60, 70, 80, 90},
                {15, 25, 35, 45},
                {27, 29, 37, 48},
                {32, 33, 39, 50, 51, 89},
              };


    for(int i=0; i<mat.length; i++) {
        for(int j=0; j<mat[i].length; j++) {
            System.out.println("Values at arr["+i+"]["+j+"] is "+mat[i][j]);
        }
    }

回答2:

Just invert the indexes' order like this:

for (int j = 0; j<array[0].length; j++){
     for (int i = 0; i<array.length; i++){

because all rows has same amount of columns you can use this condition j < array[0].lengt in first for condition due to the fact you are iterating over a matrix

回答3:

 //This is The easiest I can Imagine . 
 // You need to just change the order of Columns and rows , Yours is printing columns X rows and the solution is printing them rows X columns 
for(int rows=0;rows<array.length;rows++){
    for(int columns=0;columns <array[rows].length;columns++){
        System.out.print(array[rows][columns] + "\t" );}
    System.out.println();}

回答4:

Just change the indexes. i and j....in the loop, plus if you're dealing with Strings you have to use concat and initialize the variable to an empty Strong otherwise you'll get an exception.

String string="";
for (int i = 0; i<array.length; i++){
    for (int j = 0; j<array[i].length; j++){
        string = string.concat(array[j][i]);
    } 
}
System.out.println(string)

回答5:

Simple idea: get the lenght of the longest row, iterate over each column printing the content of a row if it has elements. The below code might have some off-by-one errors as it was coded in a simple text editor.

  int longestRow = 0;
  for (int i = 0; i < array.length; i++) {
    if (array[i].length > longestRow) {
      longestRow = array[i].length;
    }
  }

  for (int j = 0; j < longestRow; j++) {
    for (int i = 0; i < array.length; i++) {
      if(array[i].length > j) {
        System.out.println(array[i][j]);
      }
    }
  }