Java RandomAccessFile 文件写入

            public void mouseDown(MouseEvent e) {
                try{
                    //指定目标文件
                RandomAccessFile F = new RandomAccessFile("F:\\test.txt","rw");
                
                   //检索文件长度
                long filelength = F.length();
            //    String content = text.getText();
                //指针指向最后一位
                F.seek(filelength);
                
                F.writeBytes(text.getText()+"\n"+text_1.getText() + "\n"+ btnCheckButton.getVisible());
                F.close();
                
                JOptionPane.showMessageDialog(null, "writein complet");
                }catch (IOException S){
                    S.printStackTrace();
                    
                }