URL url = this.getClass().getClassLoader().getResource("resources/Ball.png");

Thead.getCurrent.load.... 

// APPROACH 1: To load from the root of jars in your classpath
Thread.currentThread().getContextClassLoader().getResourceAsStream("images/backgrounds/sky.jpg");

// APPROACH 2: To load resources relative to the package of this class (the class of 'this')
// e.g. if your class is org.stuff.Game, this will look for /org/stuff/config/settings.xml
getClass().getResourceAsStream("config/settings.xml");

//important part
File dir = new File("bin/data/users/");
          File listDir[] = dir.listFiles();
//less important part
          for (int i = 0; i < listDir.length; i++) {
             if (listDir[i].isDirectory()) {
                component = new Button(new Rectangle(275,50+i*75,100,50),listDir[i].toString().substring(15),applet);
                  component.addActionListener(this);
                  components.add((Component)component);
             }
          }