Parsing a text file in Java - need help understanding NullPointerException -

i'm new java , i'm having difficult time understanding scanner , exceptions. it's showing nullpointerexception @ "while (! line.matches("[\n\r]+"))". i'm not sure why happening. i've initialized line variable , i'm assuming if next line of scanner break line, while loop should end. if next line null entire outer loop should end. why returning nullpointerexception?

public class readfile { private static int inputs = 0;  public void main(string filename) throws exception {     url url = getclass().getresource(filename);     file file = new file(url.getpath());     parsefile(file);  }  void parsefile(file file) throws exception {     arraylist<string[]> inputs = new arraylist<string[]>();     bufferedreader br = new bufferedreader(new filereader(file));     string line = br.readline();     while (line != null){         linkedlist currentinput = new linkedlist();         if (line.contains("input")){             while (! line.matches("[\\n\\r]+")) {                 system.out.println(line);                 line = br.readline();             }         }else{             line = br.readline();         }     } } 

}

your inner loop calls br.readline(), need check null. change

while (! line.matches("[\\n\\r]+")) { 

to like

while (line != null && ! line.matches("[\\n\\r]+")) { 

or

while (! line.matches("[\\n\\r]+")) {     system.out.println(line);     line = br.readline();     if (line == null) {         break;     } }