java - define columns and rows in arraylist using hashmap -

i have hashmap key integer (represent rows no.) , value array object (has fraction numbers) hashmap<integer,arraylist<number>>

number class has methods calculation on fraction

the user should enter number of rows , columns , enter fraction numbers.

i filled hash map without errors asked retrieve fraction number entering row no. , column no following method:

the class has public method number getitem(int rowno, int colno) gets , returns specific number item in matrix according given argument. ex. getitem(2, 3) returns 1/3.

how can that?

it's similar how fill hashmap data.

as verbose steps

public number getitem(int rowno, int colno) {     // data row     arraylist<number> row = yourmap.get(rowno);     // value of specific column of row     number value = row.get(colno);     return value; } 

or shorthand

public number getitem(int rowno, int colno) {     return yourmap.get(rowno).get(colno); }