从主要活动访问CardView中的视图

Question

所以我制作了一个多个不同的CardView Layout并将其放入RecyclerView，每个cardview都有自己的类来处理视图。然后我在MainActivity中有一个浮动操作按钮，我想用它作为我的程序的启动器，但我无法访问其中一个cardview中的计时器。那么我如何在MainActivity的一个CardView中访问一个视图（Chrono）？

我已经尝试过使用来自mainactivity的findviewbyid，但它总是以null结果，因为它可能创建了recyclerview。

感谢您的帮助。

由于

CustomAdapter.java

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

private int[] mCardTypes;

public static final int TIME = 0;
public static final int MAP = 1;
public static final int COST = 2;

public static class ViewHolder extends RecyclerView.ViewHolder {
    public ViewHolder(View itemView) {
        super(itemView);
    }
}

public CustomAdapter(MainActivity main, int[] cardTypes) {
    this.main = main;
    mCardTypes = cardTypes;
}

public class ParkTimeViewHolder extends ViewHolder {
    Chronometer mTotalTime;
    Chronometer mRemainingTime;

    public ParkTimeViewHolder(View itemView) {
        super(itemView);
        this.mTotalTime = (Chronometer) itemView.findViewById(R.id.chrono_total);
        this.mRemainingTime = (Chronometer) itemView.findViewById(R.id.chrono_remaining);
      // i can only run choro.start() here
    }
}

public class MapViewHolder extends ViewHolder {
    //MapView

    public MapViewHolder(View itemView) {
        super(itemView);
        // TODO: 24-Dec-15 add map view
    }
}

public class CostViewHolder extends ViewHolder {
    TextView mCost;

    public CostViewHolder(View itemView) {
        super(itemView);
        this.mCost = (TextView) itemView.findViewById(R.id.text_view_cost);
        mCost.setText("20000");
    }
}


@Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    View v;
    if (viewType == TIME) {
        v = LayoutInflater.from(parent.getContext())
                .inflate(R.layout.card_view_time, parent, false);
        return new ParkTimeViewHolder(v);
    } else if (viewType == MAP) {
        v = LayoutInflater.from(parent.getContext())
                .inflate(R.layout.card_view_map, parent, false);
        return new MapViewHolder(v);
    } else {
        v = LayoutInflater.from(parent.getContext())
                .inflate(R.layout.card_view_cost, parent, false);
        return new CostViewHolder(v);
    }
}

@Override
public void onBindViewHolder(ViewHolder holder, int position) {
    if(holder.getItemViewType() == TIME) {
        ParkTimeViewHolder myHolder = (ParkTimeViewHolder) holder;
    } else
    if(holder.getItemViewType() == MAP) {
        MapViewHolder myHolder = (MapViewHolder) holder;
    } else
    if(holder.getItemViewType() == COST) {
        CostViewHolder myHolder = (CostViewHolder) holder;
    }
}

@Override
public int getItemCount() {
    return mCardTypes.length;
}

@Override
public int getItemViewType(int position) {
    return mCardTypes[position];
}

MainActivity.java

public class MainActivity extends AppCompatActivity implements View.OnClickListener {

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

private Chronometer mTotalChrono;

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

    mRecyclerView = (RecyclerView) findViewById(R.id.recycle_view_main_activity);
    mLayoutManager = new LinearLayoutManager(MainActivity.this);
    mRecyclerView.setLayoutManager(mLayoutManager);
    mAdapter = new CustomAdapter(this, new int[]{CustomAdapter.TIME, CustomAdapter.COST});
    mRecyclerView.setAdapter(mAdapter);

    FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
    fab.setOnClickListener(this);

}

@Override
public void onClick(View v) {
    if (v.getId() == R.id.fab) {
        Snackbar.make(v, "Started", Snackbar.LENGTH_LONG)
                .setAction("Action", null).show();
     // i need to run chrono.start(); from here
    }
}

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

Answer 1

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

private int[] mCardTypes;

public static final int TIME = 0;
public static final int MAP = 1;
public static final int COST = 2;
// create this variable
private static ParkTimeViewHolder parkTimeViewholder;

//call this function in mainactivity
public static void startChrono(){
    if(parkTimeViewholder!=null){
    // start chrono here using parkTimeViewholder variable
    }
}

public static class ViewHolder extends RecyclerView.ViewHolder {
    public ViewHolder(View itemView) {
        super(itemView);
    }
}

public CustomAdapter(MainActivity main, int[] cardTypes) {
    this.main = main;
    mCardTypes = cardTypes;
}

public class ParkTimeViewHolder extends ViewHolder {
    Chronometer mTotalTime;
    Chronometer mRemainingTime;

    public ParkTimeViewHolder(View itemView) {
        super(itemView);
        this.mTotalTime = (Chronometer) itemView.findViewById(R.id.chrono_total);
        this.mRemainingTime = (Chronometer) itemView.findViewById(R.id.chrono_remaining);
      // i can only run choro.start() here
    }
}

public class MapViewHolder extends ViewHolder {
    //MapView

    public MapViewHolder(View itemView) {
        super(itemView);
        // TODO: 24-Dec-15 add map view
    }
}

public class CostViewHolder extends ViewHolder {
    TextView mCost;

    public CostViewHolder(View itemView) {
        super(itemView);
        this.mCost = (TextView) itemView.findViewById(R.id.text_view_cost);
        mCost.setText("20000");
    }
}


@Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    View v;
    if (viewType == TIME) {
        v = LayoutInflater.from(parent.getContext())
                .inflate(R.layout.card_view_time, parent, false);
        return new ParkTimeViewHolder(v);
    } else if (viewType == MAP) {
        v = LayoutInflater.from(parent.getContext())
                .inflate(R.layout.card_view_map, parent, false);
        return new MapViewHolder(v);
    } else {
        v = LayoutInflater.from(parent.getContext())
                .inflate(R.layout.card_view_cost, parent, false);
        return new CostViewHolder(v);
    }
}

@Override
public void onBindViewHolder(ViewHolder holder, int position) {
    if(holder.getItemViewType() == TIME) {
        ParkTimeViewHolder myHolder = (ParkTimeViewHolder) holder;
        //initiate parkTimeViewholder variable
        this.parkTimeViewholder = myHolder;
    } else
    if(holder.getItemViewType() == MAP) {
        MapViewHolder myHolder = (MapViewHolder) holder;
    } else
    if(holder.getItemViewType() == COST) {
        CostViewHolder myHolder = (CostViewHolder) holder;
    }
}

@Override
public int getItemCount() {
    return mCardTypes.length;
}

@Override
public int getItemViewType(int position) {
    return mCardTypes[position];
}