android - RecyclerView 未填充(数组)

Question

我搜索了很多但找不到为什么我的 RecyclerView 没有显示所有数据。在“MySensorAdapter”中将数据打印到控制台时，值已完成。

代码如下，非常感谢。

公共(public)类 MySensorAdapter 扩展 RecyclerView.Adapter {

private String[] mKeys;
private String[] mValues;

public MySensorAdapter(HashMap<String, String> dictionary){
    mKeys = new String[dictionary.size()];
    mValues = new String[dictionary.size()];

    for(String i : dictionary.keySet()){
        int count = 0;
        mKeys[count]=i;
        mValues[count] = dictionary.get(i);
        count++;
    }

}

public static class MyViewHolder extends RecyclerView.ViewHolder{

    public TextView mTextViewTitle;
    public TextView mTextViewData;

    public MyViewHolder(View v){
        super(v);
        mTextViewTitle = v.findViewById(R.id.textViewTitle);
        mTextViewData = v.findViewById(R.id.textViewData);
    }
}

@NonNull
@Override
public MySensorAdapter.MyViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
    View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.my_sensor_item, parent, false);

    MySensorAdapter.MyViewHolder viewHolder = new MySensorAdapter.MyViewHolder(v);
    return viewHolder;
}

@Override
public void onBindViewHolder(@NonNull MySensorAdapter.MyViewHolder holder, int position) {
    String title=mKeys[position];
    String data=mValues[position];

    Log.i("DEBUG POSITION", String.valueOf(position));

    holder.mTextViewTitle.setText(title);
    holder.mTextViewData.setText(data);
}

@Override
public int getItemCount() {
    if(mKeys != null){
        Log.i("DEBUG LENGTH", String.valueOf(mKeys.length));

        return mKeys.length;
    }
    return 0;
}

编辑:也许这也有帮助。我只想在 recyclerview 中显示传感器信息

public class SensorDataActivity extends AppCompatActivity implements SensorEventListener {

private SensorManager mSensormanager;

private RecyclerView mRecyclerView;
private RecyclerView.Adapter mAdapter;
private RecyclerView.LayoutManager mLayoutManager;

private HashMap<String, String> list = new HashMap<>();

private Sensor mSensor;

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

    Intent intent = getIntent();
    int position = intent.getIntExtra("position", 0);

    Log.i("WICHTIG", String.valueOf(position));


    mSensormanager = (SensorManager) getSystemService(SENSOR_SERVICE);
    assert mSensormanager != null;
    List<Sensor> sensors = mSensormanager.getSensorList(Sensor.TYPE_ALL);



    //Debugging to be done!
    int type = sensors.get(position).getType();

    Log.i("WICHTIG", String.valueOf(type));

    mSensor = mSensormanager.getDefaultSensor(type);

    getSensorInformation(mSensor);

    mRecyclerView = findViewById(R.id.my_sensor_recycler_view);
    mRecyclerView.setHasFixedSize(true);

    mLayoutManager = new LinearLayoutManager(this);
    mRecyclerView.setLayoutManager(mLayoutManager);

    mAdapter = new MySensorAdapter(list);
    mRecyclerView.setAdapter(mAdapter);

}

private void getSensorInformation(Sensor sensor){

    list.put("Name", sensor.getName());
    list.put("Type", String.valueOf(sensor.getType()));
    list.put("Version", String.valueOf(sensor.getVersion()));

    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
        list.put("Id", String.valueOf(sensor.getId()));
        list.put("Type(String)", sensor.getStringType());
    }

    list.put("Power", String.valueOf(sensor.getPower()));
    list.put("Vendor",sensor.getVendor());
    list.put("MaximumRange",String.valueOf(sensor.getMaximumRange()));
    list.put("Resolution",String.valueOf(sensor.getResolution()));
    list.put("MinDelay",String.valueOf(sensor.getMinDelay()));


    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
        list.put("MaximumDelay",String.valueOf(sensor.getMaxDelay()));
        list.put("FifoMaxEvent",String.valueOf(sensor.getFifoMaxEventCount()));
        list.put("FifoReservedEvent",String.valueOf(sensor.getFifoReservedEventCount()));
        list.put("ReportingMode",String.valueOf(sensor.getReportingMode()));
    }

    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
        list.put("HighestDirectReportRate",String.valueOf(sensor.getHighestDirectReportRateLevel()));
    }



}

@Override
public void onSensorChanged(SensorEvent event) {

    for(int i = 0; i<event.values.length; i++) {

        String key = "Value"+String.valueOf(i);

        list.put(key, String.valueOf(event.values[i]));
    }

    mAdapter.notifyDataSetChanged();

}

@Override
public void onAccuracyChanged(Sensor sensor, int accuracy) {
    list.put("Accuracy", String.valueOf(accuracy));
    mAdapter.notifyDataSetChanged();
}

@Override
protected void onResume() {
    super.onResume();
    mSensormanager.registerListener(this, mSensor, SensorManager.SENSOR_DELAY_NORMAL);
}

@Override
protected void onPause() {
    super.onPause();
    mSensormanager.unregisterListener(this);
    }

}

Answer 1

计数值在每次重置为0

for(String i : dictionary.keySet()){
    int count = 0;
    mKeys[count]=i;
    mValues[count] = dictionary.get(i);
    count++;
}

因此，用于显示 UI 的数据集每次都只有一个元素。您可以尝试在循环外初始化计数。