2D Arrays in Java Tutorial

storing data

• referencing and storing information

<aside> 🦕 arrays: multiple space to allocate; pointing towards a data structure;

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copying arrays

when we want to make a copy of an array, the copied array will be exactly like the original and change whenever we change an element value in the original value (will change the value for both of the values)

• to solve this, we need to copy element by element

when we have each element in the array pointing to a new array for each, then we get a 2D array

• we can have those elements in the second dimension point to another array of items, creating a third dimension of arrays

<aside> 🚙 2D arrays: work as a grid as opposed to a single line of data storage

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declaring and initializing

int[][]num; //2D array of integers

• first square brackets represents about the number of rows
• second square brackets represent the number of columns

int[][] num = new int[3][5]; //allocates space for a 3 by 5 array 
//3 rows, 5 columns

• starts at top left of the "grid" and goes down

int[][]num = 
{{1, 2, 3, 4, 5},
{6, 7, 8, 9, 10},
{11, 12, 13, 14, 15}}; //2D array of 3 rows and 5 columns

accessing elements

num[1][3] //returns 9
num[row index][column index]