Question

我有一个包含Array ( [0] => ffmpeg version git-2016-07-03-1ad4471 Copyright (c) 2000-2016 the FFmpeg developers [1] => built with gcc 4.1.2 (GCC) 20080704 (Red Hat 4.1.2-55) ...和RecyclerView的应用程序，我从用户获取数据到FragmentDialog并且一切正常，但问题是当我向sql添加数据并在sqlite中显示它我必须重新启动应用程序以显示数据时，我怎么能通知数据被更改？

这是我的RecyclerView

DialogFragment

MainActivity

public class addAction extends DialogFragment implements View.OnClickListener {
    EditText addTitle, addDesc;
    Button add, clear,close;
    private DatabaseHelpher db;
    String Title,Des;

    public addAction() {
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View rootView = inflater.inflate(R.layout.addaction, container, false);
        addTitle = (EditText) rootView.findViewById(R.id.todotitle);
        addDesc = (EditText) rootView.findViewById(R.id.tododescription);
        add = (Button) rootView.findViewById(R.id.addbutton);
        add.setOnClickListener(this);
        close = (Button) rootView.findViewById(R.id.Close);
        close.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                dismiss();
            }
        });
        clear = (Button) rootView.findViewById(R.id.clear);
        clear.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                addTitle.setText("");
                addDesc.setText("");
            }
        });
        return rootView;
    }

    public void onActivityCreated(@Nullable Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);
        getDialog().setTitle("Add Action");
        db = new DatabaseHelpher(getContext());
    }

    private void insert() {
        Title = addTitle.getText().toString();
        Des= addDesc.getText().toString();
        db.insertIntoDB(Title, Des);
    }

    @Override
    public void onClick(View v) {
        if (addTitle.getText().toString().trim().equals("")) {
            addTitle.setError(" Title is required!");
        } else if (addDesc.getText().toString().trim().equals("")) {
            addDesc.setError(" Postion is required!");
        }
        Toast.makeText(getContext(),"your data is saved", Toast.LENGTH_SHORT).show();
        insert();
    }
}

来自

public class MainActivity extends AppCompatActivity {
    List<ToDoModule> dbList;
    RecyclerView mRecyclerView;
    DatabaseHelpher helpher;
    private RecyclerView.Adapter mAdapter;
    private RecyclerView.LayoutManager mLayoutManager;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);
        getSupportActionBar().hide();
        helpher = new DatabaseHelpher(this);
        dbList= new ArrayList<ToDoModule>();
        dbList = helpher.getDataFromDB();

        mRecyclerView = (RecyclerView)findViewById(R.id.AppRecyclerView);
        mRecyclerView.setHasFixedSize(true);
        mLayoutManager = new LinearLayoutManager(this);
        mRecyclerView.setLayoutManager(mLayoutManager);
        mAdapter = new RecyclerAdapter(this,dbList);
        this.dbList =helpher.getDataFromDB();
        mAdapter.notifyDataSetChanged();
        mRecyclerView.setAdapter(mAdapter);
        FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
        fab.setImageResource(R.drawable.ic_action_name);
        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                FragmentManager fm = getSupportFragmentManager();
                addAction add = new addAction();
                add.show(fm,"fragment_edit_name");
            }
        });
    }

    @Override
    protected void onResume() {
        super.onResume();
    }
}

的

getdata()方法

SQlHelper

RecyclerViewAdapter

public List<ToDoModule> getDataFromDB(){
    List<ToDoModule> modelList = new ArrayList<ToDoModule>();
    String query = "select * from "+ TODO_TABLE;
    SQLiteDatabase db = this.getWritableDatabase();
    Cursor cursor = db.rawQuery(query,null);
    if (cursor.moveToFirst()){
        do {
            ToDoModule model = new ToDoModule();
            model.setActionTitle(cursor.getString(1));
            model.setActionDesc(cursor.getString(2));
            modelList.add(model);
        }while (cursor.moveToNext());
    }
    return modelList;
}

Answer 1

~~问题在于这2行。~~

mAdapter = new RecyclerAdapter（this，dbList）;

this.dbList = helpher.getDataFromDB（）;

首先将dbList的引用设置为适配器，然后将列表的引用更改为您在getDataFromDB（）中创建的列表，并且适配器中的列表保留旧的没有项目的列表。

为了修复此更改此代码的第二行 this.dbList.addAll（helpder.getDataFromDB（））;

~~并确保调用adapter.notifyDataSetChanged（）~~

编辑：没关系，似乎你在此之前调用数据库。你确定数据库中有项目吗？

Answer 2

您需要在MainActivity中创建一个函数来更新Recycler视图中的数据。然后从对话框片段中调用该函数。在MainActivity中

public void updateData(){
       dbList =helpher.getDataFromDB();
       mAdapter = new RecyclerAdapter(this,dbList);
       mRecyclerView.setAdapter(mAdapter);
}

在对话框片段中，您可以使用界面或将活动实例添加到MainActivity

来执行相同的操作

((MainActivity) grtActivity()).updateData();

或者使用界面。

如何通知数据是从sqlite更改为recycleler视图？

2 个答案: