#vulnerable code 
                              public static String input(String msg, String preset, String title, boolean hidden) {
    JFrame anchor = popLocation();
    String ret = "";
    if (!hidden) {
      if ("".equals(title)) {
        title = "Sikuli input request";
      }
      ret = (String) JOptionPane.showInputDialog(anchor, msg, title, 
              JOptionPane.PLAIN_MESSAGE, null, null, preset);
    } else {
      preset = "";
      JTextArea tm = new JTextArea(msg);
      tm.setColumns(20);
      tm.setLineWrap(true);
      tm.setWrapStyleWord(true);
      tm.setEditable(false);
      tm.setBackground(new JLabel().getBackground());
      JPasswordField pw = new JPasswordField(preset);
      JPanel pnl = new JPanel();
      pnl.setLayout(new BoxLayout(pnl, BoxLayout.Y_AXIS));
      pnl.add(pw);
      pnl.add(Box.createVerticalStrut(10));
      pnl.add(tm);
      int retval = JOptionPane.showConfirmDialog(anchor, pnl, title, JOptionPane.OK_CANCEL_OPTION);
      if (0 == retval) {
        char[] pwc = pw.getPassword();
        for (int i = 0; i < pwc.length; i++) {
          ret = ret + pwc[i];
          pwc[i] = 0;
        }
      } 
    }
    anchor.dispose();
    return ret;
  } 
                            #location 33 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                              public static String input(String msg, String preset, String title, boolean hidden) {
    JFrame anchor = popLocation();
    String ret = "";
    if (!hidden) {
      if ("".equals(title)) {
        title = "Sikuli input request";
      }
      ret = (String) JOptionPane.showInputDialog(anchor, msg, title, 
              JOptionPane.PLAIN_MESSAGE, null, null, preset);
    } else {
      preset = "";
      JTextArea tm = new JTextArea(msg);
      tm.setColumns(20);
      tm.setLineWrap(true);
      tm.setWrapStyleWord(true);
      tm.setEditable(false);
      tm.setBackground(new JLabel().getBackground());
      JPasswordField pw = new JPasswordField(preset);
      JPanel pnl = new JPanel();
      pnl.setLayout(new BoxLayout(pnl, BoxLayout.Y_AXIS));
      pnl.add(pw);
      pnl.add(Box.createVerticalStrut(10));
      pnl.add(tm);
      int retval = JOptionPane.showConfirmDialog(anchor, pnl, title, JOptionPane.OK_CANCEL_OPTION);
      if (0 == retval) {
        char[] pwc = pw.getPassword();
        for (int i = 0; i < pwc.length; i++) {
          ret = ret + pwc[i];
          pwc[i] = 0;
        }
      } 
    }
    if (anchor != null) {
      anchor.dispose();
    }
    return ret;
  }