如何保存在android的矢量对象？

问题描述

我一直在寻找周围很多，无法做到这一点。我创建了一个类的VectorEx，延长矢量，存储两种方法，一种用于保存矢量，一个用于加载它。我知道我必须使用的FileOutputStream和openFileInput（），但我无法创建文件。我仍然在pretty新到Android程序，因此一个简单的解释就是AP preciated。

I've been searching around a lot and couldn't accomplish this. I have created a class 'VectorEx', extending 'Vector', to store two methods, one for saving the vector and one for loading it. I know i have to use FileOutputStream and openFileInput() but I'm unable to create the file. I'm still pretty new to android programming, so a simple explanation is appreciated.

public class VectorEx extends Vector<Subject> {
public void save(String name, Context ctx) {
    try {
        File file = new File(name);
        if(!file.exists()) {
            file.createNewFile();
        }
        FileOutputStream fos = ctx.openFileOutput(name, Context.MODE_PRIVATE);
        ObjectOutputStream oos = new ObjectOutputStream(fos);
        oos.writeObject(this);
        oos.close();
    }
    catch(IOException e) {
        e.printStackTrace();
    }
}

public void load(String name, Context ctx) {
    try {
        FileInputStream fis = ctx.openFileInput(name);
        ObjectInputStream ois = new ObjectInputStream(fis);
        ois.readObject();
    }
    catch(IOException e) {
        e.printStackTrace();
    }
    catch(ClassNotFoundException e) {
        e.printStackTrace();
    }
}
}

这是code我上次使用试过。无论从任何我能理解LogCat中的，似乎这是一个只读文件系统。

This is the code I last tried using. From whatever I could understand of LogCat, it seems that this is a "Read-only file system".

推荐答案

这些权限也许之一是缺少在AndroidManifest：

Maybe one of these permission is missing in your AndroidManifest:

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

<uses-permission android:name="android.permission.WRITE_INTERNAL_STORAGE" />

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