java - Null pointer exception when ran outside netbeans -

when run bit of code outside of netbeans null pointer exception. i'm trying read .dat file. works fine in netbeans. i've checked path many times , right. class loader or supposed used?

static string filename = "src/frogger/highscores.dat"; try {         //make filereader object read file         file = new filereader(new file(filename));         filestream = new bufferedreader(file);      } catch (exception e) {         system.out.println("file not found");     } 

i imagining being used images, doesn't work.

 file = new filereader(new file(this.getclass().getresource(filename))); 

or

file = new filereader(this.getclass().getresource(filename)); 

error

microsoft windows [version 6.1.7601] 

copyright (c) 2009 microsoft corporation. rights reserved.

c:\users\michael>java -jar "c:\users\michael\documents\netbeansprojects\frogger\ dist\frogger.jar" file not found exception in thread "main" java.lang.nullpointerexception         @ frogger.board.readfile(board.java:519)     @ frogger.board.gameinit(board.java:154)     @ frogger.board.addnotify(board.java:111)     @ java.awt.container.addnotify(unknown source)     @ javax.swing.jcomponent.addnotify(unknown source)     @ java.awt.container.addnotify(unknown source)     @ javax.swing.jcomponent.addnotify(unknown source)     @ java.awt.container.addnotify(unknown source)     @ javax.swing.jcomponent.addnotify(unknown source)     @ javax.swing.jrootpane.addnotify(unknown source)     @ java.awt.container.addnotify(unknown source)     @ java.awt.window.addnotify(unknown source)     @ java.awt.frame.addnotify(unknown source)     @ java.awt.window.show(unknown source)     @ java.awt.component.show(unknown source)     @ java.awt.component.setvisible(unknown source)     @ java.awt.window.setvisible(unknown source)     @ frogger.window.<init>(window.java:16)     @ frogger.window.main(window.java:22) 

the file in package frogger on netbeans.

your code refers src folder ought not present anymore, if code deployed. right way access resources be

// no src/ in resource name inputstream is=getclass().getresourceasstream("/frogger/highscores.dat"); filestream = new bufferedreader(new inputstreamreader(file)); 

your ide typically copies resources src location of generated class files. if deploy application have care file packaged it.

if frogger matches package name of class can relative lookup

inputstream is=getclass().getresourceasstream("highscores.dat"); 

note nullpointerexception comes naturally catching ioexception , proceeding nothing has happened uninitialized reader. should rather ensure code dealing resource not executed when allocation fails.

but things highscores should consider preferences api instead gives persistent storage independent application’s location.