how to create general method for all type of class(object)

Question

I am using db4o lib for storing data.

for example I have this code for storing data (ie News)

public static void insertNewsToDB(Context context, final News news){
        final String dbPath = context.getDir("news", Context.MODE_PRIVATE) + "/"  + DB4O_NAME;
        ObjectContainer db = Db4oEmbedded.openFile(Db4oEmbedded.newConfiguration(), dbPath);
        try {
            db.store(news);
            db.commit();
        } finally {
            db.close();
        }
    }

and this getting data from db:

public static List<News> getNewsListFromDB(Context context){
        final List<News> news = new ArrayList<News>();
        final String dbPath = context.getDir("news", Context.MODE_PRIVATE) + "/"  + DB4O_NAME;
        ObjectContainer db = Db4oEmbedded.openFile(Db4oEmbedded.newConfiguration(), dbPath);
        try {
            ObjectSet<News> result = db.queryByExample(News.class);
            news.addAll(result);
        } finally {
            db.close();
        }

        return news;
    }

How could I create method so it's not depend on what type of class I have to pass. More clearly it doesn't depend on second parameter is News,User or something else. And same when I want get news from db.

I need to create general method which is not depend on type of class.

EDIT: I did this but I doesn't work. More clearly trying get list it returns nothing. And I don't get it why what I did wrong

 public static void insertToDB(Context context, final Object obj,final String _key) {
        final String dbPath = context.getDir(_key, Context.MODE_PRIVATE) + "/" + DB4O_NAME;
        ObjectContainer db = Db4oEmbedded.openFile(Db4oEmbedded.newConfiguration(), dbPath);
        try {
            db.store(obj);
            db.commit();
        } finally {
            db.close();
        }
    }
    public static <T> void insertToDB(Context context, final List<T> newsList,String _key) {
        for (T news : newsList) {
            insertToDB(context, news,_key);
        }
    }

    public static <T> List<T> getListFromDB(Context context, final java.lang.Class<T> tClass,final String _key) {
        final List<T> news = new ArrayList<T>();
        final String dbPath = context.getDir(_key, Context.MODE_PRIVATE) + "/" + DB4O_NAME;
        ObjectContainer db = Db4oEmbedded.openFile(Db4oEmbedded.newConfiguration(), dbPath);
        try {
            ObjectSet<T> result = db.queryByExample(tClass);
            news.addAll(result);
        } finally {
            db.close();
        }
        return news;
    }

Answer 1

使用Object作为方法参数类型或者您可以根据需要使用泛型（？或T）

Answer 2

If you need no type information at all, you could simple switch News to Object . If you need type information (ie, persisted objects stick to a certain interface), introduce a generic type parameter.

public static <T extends SomeClass> void insertEntityToDB(Context context, final T entity) {
    // ...
}

public static <T extends SomeClass> List<T> getEntityListFromDB(Context context) {
    // ...
}

Answer 3

You need to implement the concept of Generics in your method calls.

public static void insertNewsToDB(Context context, final News news)

will change to

public static void insertNewsToDB(Context context, final <T> T)

And

public static List<News> getNewsListFromDB(Context context)

will change to

public static List<T> getNewsListFromDB(Context context)