java 2D arrays

Two Dimensional Arrays

A collection of data that is stored in a table or grid, with rows and columns.

Rows

Horizontal

Columns

Vertical

declaration statement

datatype[][] nameOfArray = new dataType[][];

int[][] myTable = new int [4][7];

remember

• first spot starts at 0

• go down first, then to the side

• when declaring, it counts normally

• when choosing a spot, start from 0

grid.length

the number of rows

grid [0].length

number of columns

Traversing

for (int r = 0; r < myTable.length; r++ )

{

  for (int c = 0; c < myTable[0].length; c++)

   {

system.out.println(myTable[r][c]);

   }

}

Populating with an initializer list

int [][] grid = {  { 5, 2, 12, -4, 95} ,        //row 0

                   { 33, 59, 23, 68, 200},      //row 1

                   { 42, 87, -99, 312, 0}  } ;  //row 2