java - Building two 2-D arrays from file data -

i'm tasked writing 2 matrices file (which have done), read data file perform various calculations. having difficulty rebuilding each matrix within method perform calculations. decided use arraylist of arraylist, in order 2-d matrix need. using bufferedreader, need loop through 1 matrix, adding elements 1 arraylist, second matrix. added titles above matrices act markers find matrix data want use. there better way it?

public void sum() throws ioexception {      arraylist<arraylist<integer>> matrixarray = new arraylist<>();      while(br.read() != -1) {         arraylist row = new arraylist();          //tried this, using 2 println spaces between matrices         //but realized can't use readline way              while(!br.readline().equals("\n\n")) {             row.add(br.read());         }         matrixarray.add(row);        } 

the file data of form:

matrix 1  b c  d  matrix 2  b c  d 

--update--from comment below

while(file.hasnext()) { if(file.hasnext("matrix one")){     //fill arraylist row data until \n     while(file.hasnextint()) {         row.add(file.nextint());     }           matrixone.add(row);     }      else if(file.hasnext("matrix two")) {        row.clear();          while(file.hasnextint()) {              row.add(file.nextint());          }          matrixtwo.add(row);     }    } 

you should use java.util.scanner class. easier use, , allows read line line.

once separate lines, can call string#split method separate numbers using spaces.

this give array of strings. can call integer.parseint method retrieve int string , add arraylist.

hope helps.