Question

我通过将AlertDialog与cardView一起使用来收集数据，因此用户可以输入其数据。然后，我将数据传递到数据库。之后，我使用RecyclerView Adapter并在RecyclerView上显示它们

我想使用RecyclerView Adapter显示我的数据，然后在RecyclerView上显示它们，但是当我运行该应用程序时，它崩溃了。

它表明我的问题是我没有EventListAdapter，但是我有并且检查了几次。请帮助我，非常感谢。

主要活动

public class eventListPage_3 extends AppCompatActivity {

private RecyclerView recyclerView;
private EventListAdapter adapter;
private List<Event> eventList;
private List<Event> eventItems;
private DatabaseHandler db;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_event_list_3);
    Toolbar toolbar =  findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);

    FloatingActionButton fab = findViewById(R.id.fab);
    fab.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {

        }
    });

    db = new DatabaseHandler(this);
    recyclerView = findViewById(R.id.eventListView);
    recyclerView.setHasFixedSize(true);
    recyclerView.setLayoutManager(new LinearLayoutManager(this));

    eventList = new ArrayList<>();
    eventItems = new ArrayList<>();


    // get all events
    eventList = db.GetAllEvents();

    for (Event e : eventList){
        Event event = new Event();
        event.setId(e.getId());
        event.setTime(e.getTime());
        event.setDescription(e.getDescription());

        eventItems.add(event);
    }

    adapter = new EventListAdapter(this, eventItems);
    recyclerView.setAdapter(adapter);
    adapter.notifyDataSetChanged();
}}

适配器

public class EventListAdapter extends RecyclerView.Adapter<EventListAdapter.ViewHolder> {

private Context context;
private List<Event> eventList;

public EventListAdapter(Context context, List<Event> eventList) {
    this.context = context;
    this.eventList = eventList;
}

@NonNull
@Override
public EventListAdapter.ViewHolder onCreateViewHolder(@NonNull ViewGroup viewGroup, int i) {

    View view = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.list_row, viewGroup, false);

    return new ViewHolder(view, context);
}

@Override
public void onBindViewHolder(@NonNull EventListAdapter.ViewHolder viewHolder, int i) {

    Event event = eventList.get(i);
    viewHolder.time.setText(event.getTime());
    viewHolder.description.setText(event.getDescription());

}

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

public class ViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener{

    public TextView time;
    public TextView description;
    public Button edit;
    public Button delete;
    public int id;

    public ViewHolder(@NonNull View itemView, Context ctx) {
        super(itemView);

        context = ctx;

        time = itemView.findViewById(R.id.time);
        description = itemView.findViewById(R.id.description);

        edit = itemView.findViewById(R.id.editedButton);
        delete = itemView.findViewById(R.id.deleteButton);

        edit.setOnClickListener(this);
        delete.setOnClickListener(this);

        itemView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {

            }
        });

    }

    @Override
    public void onClick(View view) {
        switch (view.getId()){
            case R.id.editedButton:

            break;

            case R.id.deleteButton:

            break;
        }

    }
}}

我的数据库类

public class DatabaseHandler extends SQLiteOpenHelper {

private Context context;
public DatabaseHandler(Context context) {
    super(context, Database_Constants.DB_NAME, null, Database_Constants.DB_VERSION);
    this.context = context;
}

@Override
public void onCreate(SQLiteDatabase db) {

    String CREATE_EVENT_TABLE = "CREATE TABLE " + Database_Constants.TABLE_NAME + "("
            + Database_Constants.KEY_ID + " INTEGER PRIMARY KEY," + Database_Constants.KEY_EVENT_TIME
            + " TEXT," + Database_Constants.KET_EVENT_DESCRIPTION + " TEXT);";

    db.execSQL(CREATE_EVENT_TABLE);

}

@Override
public void onUpgrade(SQLiteDatabase db, int i, int i1) {

    db.execSQL("DROP TABLE IF EXISTS " + Database_Constants.TABLE_NAME);
    onCreate(db);
}

//Add
public void AddEvent(Event event){

    SQLiteDatabase db = this.getWritableDatabase();

    ContentValues values = new ContentValues();
    values.put(Database_Constants.KEY_EVENT_TIME, event.getTime());
    values.put(Database_Constants.KET_EVENT_DESCRIPTION, event.getDescription());

    db.insert(Database_Constants.TABLE_NAME, null, values);

}



//Get All Events
public List<Event> GetAllEvents(){

    SQLiteDatabase db = this.getReadableDatabase();

    List<Event> events = new ArrayList<>();

    Cursor cursor = db.query(Database_Constants.TABLE_NAME, new String[]{Database_Constants.KEY_ID,
     Database_Constants.KEY_EVENT_TIME, Database_Constants.KET_EVENT_DESCRIPTION}, null,
            null,null, null, Database_Constants.KEY_ID + " DESC");

    if (cursor.moveToFirst()){
        do {
            Event event = new Event();
            event.setId(Integer.parseInt(cursor.getString(cursor.getColumnIndex(Database_Constants.KEY_ID))));
            event.setTime(cursor.getString(cursor.getColumnIndex(Database_Constants.KEY_EVENT_TIME)));
            event.setDescription(cursor.getString(cursor.getColumnIndex(Database_Constants.KET_EVENT_DESCRIPTION)));

            events.add(event);

        }while (cursor.moveToNext());
    }

    return events;
}


//Update
public int UpdateEvents(Event event){

    SQLiteDatabase db = this.getWritableDatabase();

    ContentValues values = new ContentValues();
    values.put(Database_Constants.KEY_EVENT_TIME, event.getTime());
    values.put(Database_Constants.KET_EVENT_DESCRIPTION, event.getDescription());



    return db.update(Database_Constants.TABLE_NAME, values, Database_Constants.KEY_ID + "=?",
            new String[]{String.valueOf(event.getId())});
}


//Delete
public void DeleteEvents(int id){

    SQLiteDatabase db = this.getWritableDatabase();

    db.delete(Database_Constants.TABLE_NAME, Database_Constants.KEY_ID + "=?",
            new String[]{String.valueOf(id)});

    db.close();}}

具有AlertDialog的我的活动可以收集我的数据

public class MainPage_2 extends AppCompatActivity {

private AlertDialog.Builder dialogBuilder;
private AlertDialog alertDialog;
private EditText time;
private EditText description;
private Button saveButton;

private DatabaseHandler db;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main_page_2);

    db = new DatabaseHandler(this);

    Toolbar toolbar = findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);

    FloatingActionButton fab = findViewById(R.id.fab);
    fab.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {

            create_eventList();
        }
    });
}

private void create_eventList(){

    dialogBuilder = new AlertDialog.Builder(this);
    View view = getLayoutInflater().inflate(R.layout.event_create_3, null);
    time = view.findViewById(R.id.time);
    description = view.findViewById(R.id.description);
    saveButton = view.findViewById(R.id.save_button);

    dialogBuilder.setView(view);
    alertDialog = dialogBuilder.create();
    alertDialog.show();

    saveButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {

            saveEventToDatabase(view);
        }
    });


}

private void saveEventToDatabase(View v){

    Event event = new Event();

    String newTime = time.getText().toString();
    String newDescription = description.getText().toString();

    event.setTime(newTime);
    event.setDescription(newDescription);

    db.AddEvent(event);

    Snackbar.make(v, "event Saved!", Snackbar.LENGTH_LONG).show();

    new Handler().postDelayed(new Runnable() {
        @Override
        public void run() {
            alertDialog.dismiss();

            //start a new activity
            startActivity(new Intent(MainPage_2.this, eventListPage_3.class));
        }
    }, 1000); //1 sec

}}

logcat屏幕截图：

当我要存储来自AlertDialog的数据并将其传递到数据库然后传递给recyclerView时，会显示错误消息

0 个答案: