Android RecyclerView + ActiveAndroid

Question

Android RecyclerView + ActiveAndroid

androidandroid-recyclerviewactiveandroid

4

如何使用ActiveAndroid ORM来填充RecyclerView并跟踪数据更改是首选的方法？

我最近提出了一个问题，但它变得太冗长了，人们非常懒惰，几乎没有人会读到最后。

其实质是：有人有通过ActiveAndroid从数据库填充RecyclerView的工作示例吗？

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3个回答

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- Jeffy Lee · Answer 1

我使用EventBus来通知我的RecyclerView适配器，每当我向数据库添加数据时。

MainActivity.java

public class MainActivity extends AppCompatActivity implements View.OnClickListener {
    private final String TAG = "MainActivity";
    private EditText etName, etAge;
    private Button btnAdd;
    private EventBus bus = EventBus.getDefault();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        //declare all views
        etName = (EditText) findViewById(R.id.et_name);
        etAge = (EditText) findViewById(R.id.et_age);
        btnAdd = (Button) findViewById(R.id.btn_add);

        //add onClickListener to button
        btnAdd.setOnClickListener(this);

        android.support.v4.app.FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
        transaction.replace(R.id.frame_layout, ListFragment.newInstance());
        transaction.commit();
    }

    @Override
    public void onClick(View v) {
        int id = v.getId();

        switch (id) {
            case R.id.btn_add:
                PersonModel personModel = new PersonModel();

                if (isEmpty(etName) || isEmpty(etAge)) {
                    Toast.makeText(this, "Please fill in all details", Toast.LENGTH_LONG).show();
                } else {
                    personModel.name = etName.getText().toString();
                    personModel.age = etAge.getText().toString();

                    //Save data to database
                    personModel.save();

                    //Broadcast the event to notify fragment
                    bus.post("NOTIFY");
                }
                break;
            default:
                Log.e(TAG, "Invalid view ID");
                break;
        }
    }

    //Check edit text whether is empty or not
    private boolean isEmpty(EditText etText) {
        return etText.getText().toString().trim().length() == 0;
    }
}

PersonModel.java

@Table(name = "PersonModel")
public class PersonModel extends Model {
    @Column(name = "NAME")
    public String name;

    @Column(name = "AGE")
    public String age;
}

PersonAdapter.java

public class PersonAdapter extends RecyclerView.Adapter<PersonAdapter.MyViewHolder> {
    private Context mContext;
    private List<PersonModel> models;

    public PersonAdapter(Context context, List<PersonModel> models) {
        this.mContext = context;
        this.models = models;
    }

    public class MyViewHolder extends RecyclerView.ViewHolder {
        public TextView name, age;

        public MyViewHolder(View itemView) {
            super(itemView);

            name = (TextView) itemView.findViewById(R.id.name);
            age = (TextView) itemView.findViewById(R.id.age);
        }
    }

    @Override
    public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View itemView = LayoutInflater.from(mContext).inflate(R.layout.person_cell, parent, false);

        return new MyViewHolder(itemView);
    }

    @Override
    public void onBindViewHolder(MyViewHolder holder, int position) {
        PersonModel personModel = models.get(position);

        holder.name.setText(personModel.name);
        holder.age.setText(personModel.age);
    }

    @Override
    public int getItemCount() {
        return models.size();
    }
}

ListFragment.java

public class ListFragment extends Fragment {
    private final String TAG = "ListFragment";
    private EventBus bus = EventBus.getDefault();
    private List<PersonModel> models = new ArrayList<PersonModel>();
    private Context mContext;
    private RecyclerView recyclerView;
    private PersonAdapter personAdapter;

    public static ListFragment newInstance() {
        // Required empty public constructor
        ListFragment listFragment = new ListFragment();

        return listFragment;
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        View rootView = inflater.inflate(R.layout.fragment_list, container, false);

        bus.register(this);

        recyclerView = (RecyclerView) rootView.findViewById(R.id.list_rv);

        //Load and add all data from database to array list
        models = getAll();

        personAdapter = new PersonAdapter(mContext, models);
        RecyclerView.LayoutManager mLayoutManager = new LinearLayoutManager(mContext);
        recyclerView.setLayoutManager(mLayoutManager);
        recyclerView.setItemAnimator(new DefaultItemAnimator());
        recyclerView.setAdapter(personAdapter);
        personAdapter.notifyDataSetChanged();

        return rootView;
    }

    //Load all data from database
    private List<PersonModel> getAll() {
        return new Select()
                .all()
                .from(PersonModel.class)
                .orderBy("NAME ASC")
                .execute();
    }

    //Load the last data added to database
    private List<PersonModel> getLast() {
        return new Select()
                .all()
                .from(PersonModel.class)
                .orderBy("NAME DESC")
                .limit(1)
                .execute();
    }

    //Subscribe to event bus
    //Receive notification/event from MainActivity when added a data to database
    @Subscribe(threadMode = ThreadMode.MAIN)
    public void onEventMainThread(String STATUS) {
        switch (STATUS) {
            case "NOTIFY":
                //Add last added item to current array list
                models.add(getLast().get(0));

                //refresh recyclerView's adapter
                personAdapter.notifyDataSetChanged();
                break;
            default:
                Log.e(TAG, "Invalid STATUS");
        }
    }

    @Override
    public void onAttach(Context context) {
        super.onAttach(context);

        this.mContext = context;
    }
}

- Tin Tran · Answer 2

可以使用模式来实现这个功能。使用BroadcastReceiver在数据库发生更改时通知您的活动（只需向您的活动发送显式意图并实现activity.onNewIntent()）。

使用LocalBroadcastManager在将更改添加到数据库后向您的BroadCastReceiver发送广播。希望这可以帮助您。

- hello_world · Answer 3

我曾经使用过这个库，但是在 ListView 中使用。我想这段代码应该可以在 RecyclerView 中使用：

/* The database */
@Table(name = "Person")
public class Person extends Model {
    @Column(name = "Name")
    public String name;    
    @Column(name = "Age")
    public int age;
}


/* Your MainActivity */

List<Person> list = new ArrayList<>();
private RecyclerView rv;

/* Activity onCreate */
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity);

    list = getList(15);
    rv = (RecyclerView) findViewById(R.id.recycler_view);
    rv.setLayoutManager(new LinearLayoutManager(this));
    rv.setAdapter(new Adapter());

}

private List<Person> getList(int age){
    return new Select()
        .from(Person.class)
        .where("Age = ?", age)
        .orderBy(/* order you like */)
        .executeSingle();
}

private class Adapter extends RecyclerView.Adapter<Adapter.Holder> {

        @Override
        public Adapter onCreateViewHolder(ViewGroup parent, int viewType) {
            // you should inflate the layout you want be laid in every row of the recycler view. Im just inflating a text view for convinence
            return new Holder(LayoutInflater.from(parent.getContext()).inflate(android.R.layout.simple_list_item_1, parent, false));
        }

        @Override
        public void onBindViewHolder(Holder holder, int position) {
            // assign values to all view in the holder.
            holder.tv.setText(list.get(position).name);
        }

        @Override
        public int getItemCount() {
            return list.size();
        }

        public class Holder extends RecyclerView.ViewHolder {
            // here you load all the view in your layout
            TextView tv;

            public Holder(View itemView) {
                super(itemView);
                tv = (TextView) itemView;
            }
        }
    }

在这里，我假设您已经创建并存储了数据库中的值，因为问题只要求从数据库填充。

我还没有测试过它，但我认为它应该可以工作。