java - adding JFrame background caused .JAR to be broken -

i want know problem in code caused .jar file broken? when double click on jar file doesn't open fine before adding background image jframe.

i created class called cube draw cube , want set background image jframe, added field in cube class

private bufferedimage bg; 

bg initialization in class constructor

publice cube() { bg = imageio.read(new file("bg_image.jpg")); } 

this piece of code used set background

@override public void paintcomponent(graphics g) {      super.paintcomponent(g);     g.drawimage(bg, 0, 0, this); } 

in main class created jframe object draw cube

    jframe jf = new jframe();     jf.add(new cube());     jf.setenabled(true);     jf.setdefaultcloseoperation( jframe.exit_on_close );     jf.setresizable(false);     jf.setsize( 500, 500 );     jf.setvisible( true ); 

since not have jar file there no way me know problem. need access file resource , not new file because inside jar. first should use cmd run jar , see if gives stack trace. use command: java -jar filename.jar run jar via command prompt.

try using:

cube.class.getresourceasstream("bg_image.jpg");