Java - 从 BIN 文件读取数组或将数组写入 BIN 文件

Question

我正在开发一个小型图书馆应用程序，它以这种格式存储技术手册:

目前，我正在尝试将库的内容保存并根据用户的需要加载到 bin 文件中。

但是，当我尝试加载库文件时，唯一的变化是“-1”被打印到控制台。此处显示:

理想情况下，我希望将加载的手册存储到用户当前的库中。

这是我的代码:

//Choice 7: Load Library:

            if(Menu.menuChoice == 7){
                boolean loadYesNo = Console.readYesNo("\n\nThe manualKeeper app is able to load and display any 'Library.txt' files \nfound in your home folder directory.\n\nWould you like to load and display library? (Y/N):\n");
                String fileName = "Library.bin";
                if(loadYesNo==true){
                try {
                    FileInputStream fileIs = new FileInputStream(fileName);
                    ObjectInputStream is = new ObjectInputStream(fileIs);
                    Object x = is.read();
                    System.out.println(x);
                    is.close();
                } catch (FileNotFoundException e) {
                    e.printStackTrace();
                } catch (IOException e) {
                    e.printStackTrace();
                }
                Menu.displayMenu();
                }
                else if(loadYesNo==false){
                    System.out.println("\n\n--------------------------------------------------------------------------");
                    System.out.println("\n                             Library not loaded!\n");
                    System.out.println("--------------------------------------------------------------------------\n");
                    Menu.displayMenu();
                }
            }

//Choice 0: Exit the program:

            if(Menu.menuChoice == 0){
                if(Menu.menuChoice == 0){
                    if(Library.ManualList.size() > 0){
                        boolean saveYesNo = Console.readYesNo("\nThe manualKeeper app is able to save your current library to a '.txt' \nfile in your home folder directory (C:\\Users\\ 'YOUR NAME').\n\nWould you like to save the current library? (Y/N):\n");
                        String fileName = "Library.bin";
                        if(saveYesNo==true){
                            try {
                                FileOutputStream fileOs = new FileOutputStream(fileName);
                                ObjectOutputStream os = new ObjectOutputStream(fileOs);
                                for (int i = 0; i < Library.ManualList.size(); i++){
                                    os.writeObject(Library.ManualList.get(i).displayManual());
                                    os.close();
                                }
                            } catch (FileNotFoundException e) {
                                e.printStackTrace();
                            } catch (IOException e) {
                                e.printStackTrace();
                            }
                            System.out.println("DONE WRITING!");
                        }
                            else if(saveYesNo==false){
                                System.out.println("\n\n--------------------------------------------------------------------------");
                                System.out.println("\n                              Library not saved!\n");
                                System.out.println("--------------------------------------------------------------------------\n");
                                break exit;
                        }
                        Menu.displayMenu();
                    }else if(Library.ManualList.isEmpty()){ 
                        Menu.displayMenu();
                    }
                }
            }               

        }
    System.out.println("\n              ~   You have exited the manualKeeper app!   ~                  ");
    System.out.println("\n                  Developed by Oscar Moore - 2014 - UWL\n");
    System.out.println("\n                                   <3\n");

}
}

如果需要显示更多代码，请告诉我。谢谢。

Answer 1

行:

对象 x = is.read();
System.out.println(x);

结果是您在控制台中看到的 -1。

从 javadocs ( link ) 中，read() 返回:

-1 if the end of the stream is reached.

因此，首先检查 Library.bin 是否已正确保存(保存后使用文本编辑器)。

然后，确保您正在读取的文件是同一个文件。

您似乎没有使用文件的完整路径。例如Library.bin 与 /home/project/Library.bin。尝试使用完整路径。我怀疑这就是问题所在。