How Do I Save And Multiple Objects From A Single File?

I want my app to store multiple objects locally for later use. Now, my problem is that I know how to load an object from an ObjectInputStream by taking the entire file(federations.

Solution 1:

You can use it like this..

ArrayList<Object> arrayList = newArrayList<Object>();

Object obj = null;

while ((obj = ois.readObject()) != null) {
    arrayList.add(obj);
}

You can return an ArrayList on your method.

return arrayList;

Edit: Full code would be like this..

publicstaticArrayList<Object> load(Context ctx, String filename) 
{
    InputStream fis = null;
    ObjectInputStream ois = null;

    ArrayList<Object> arrayList = newArrayList<Object>();

    Object loadedObj = null;
    try {
        fis = ctx.openFileInput(filename);
        ois = newObjectInputStream(fis);

        while ((loadedObj = ois.readObject()) != null) {
             arrayList.add(loadedObj);
        }
    } catch (Exception e) {
        e.printStackTrace();
        returnnull;
    } finally {
        if (null != ois) ois.close();
        if (null != fis) fis.close();
    }

    return arrayList;
}

Hope it helps..

Solution 2:

An extention to @Jan 's code, fixing the problem of keeping ois open if an exception is thrown, along with some minor issues.

publicstatic ArrayList<Object> load(Context ctx, String filename)throws FileNotFoundException {
    InputStreaminstream= ctx.openFileInput(filename);

    ArrayList<Object> objects = newArrayList<Object>();

    try {
        ObjectInputStreamois=newObjectInputStream(instream);
        try{
            ObjectloadedObj=null;
            while ((loadedObj = ois.readObject()) != null) {
                objects.add(loadedObj);
            }

            return objects;
        }finally{
            ois.close();
        }

    } catch (StreamCorruptedException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    } catch (ClassNotFoundException e) {
        e.printStackTrace();
    }
    returnnull;
}