Java 从主活动访问CardView中的视图

所以我制作了多个不同的CardView布局并将其放入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，我想用它作为我程序的启动程序，但我无法访问其中一个cardview中的chrono。那么如何从MainActivity访问其中一个CardView中的视图（Chrono）

我已经尝试从mainactivity使用findviewbyid，但它的结果始终为null，因为可能recyclerview尚未创建

谢谢你的帮助

谢谢

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];
}

公共类CustomAdapter扩展了RecyclerView.Adapter{ 私有int[]mCardTypes； 公共静态最终整数时间=0； 公共静态最终整数映射=1； 公共静态最终成本=2； //创建此变量 专用静态驻车时间视窗持有人驻车时间视窗持有人； //在mainactivity中调用此函数 公共静态void startChrono（）{ if（驻车时间视图持有人！=null）{ //使用parkTimeViewholder变量在此处开始计时 } } 公共静态类ViewHolder扩展了RecyclerView.ViewHolder{ 公共视图持有者（视图项视图）{ 超级（项目视图）； } } 公共CustomAdapter（MainActivity main，int[]cardTypes）{ this.main=main； mCardTypes=cardTypes； } 公共类驻车时间视窗持有者扩展了视窗持有者{ 天文钟MTO时间； 天文钟磁共振成像时间； 公共停车时间视图持有人（查看项目视图）{ 超级（项目视图）； this.mTotalTime=（Chronometer）itemView.findViewById（R.id.chrono_总计）； this.mRemainingTime=（Chronometer）itemView.findViewById（R.id.chrono_剩余）； //我只能在这里运行choro.start（） } } 公共类MapViewHolder扩展了ViewHolder{ //地图视图 公共地图视图持有者（查看项目视图）{ 超级（项目视图）； //待办事项：2015年12月24日添加地图视图 } } 公共类CostViewHolder扩展了ViewHolder{ 文本视图mCost； 公共成本视图持有人（查看项目视图）{ 超级（项目视图）； this.mCost=（TextView）itemView.findViewById（R.id.text\u view\u cost）； mCost.setText（“20000”）； } } @凌驾 public ViewHolder onCreateViewHolder（视图组父级，int-viewType）{ 观点五； 如果（viewType==时间）{ v=LayoutInflater.from（parent.getContext（）） .充气（R.layout.card\u view\u time，parent，false）； 返回新的驻车时间视图保持架（v）； }else if（viewType==MAP）{ v=LayoutInflater.from（parent.getContext（）） .充气（R.layout.card\u view\u map，父级，假）； 返回新的MapViewHolder（v）； }否则{ v=LayoutInflater.from（parent.getContext（）） .充气（R.layout.card\u view\u cost，parent，false）； 返回新的CostViewHolder（v）； } } @凌驾 公共无效onBindViewHolder（ViewHolder，int位置）{ if（holder.getItemViewType（）=时间）{ 停车时间视图持有人myHolder=（停车时间视图持有人）持有人； //启动parkTimeViewholder变量 this.parkTimeViewholder=myHolder； }否则 if（holder.getItemViewType（）==MAP）{ MapViewHolder myHolder=（MapViewHolder）holder； }否则 if（holder.getItemViewType（）=成本）{ CostViewHolder myHolder=（CostViewHolder）holder； } } @凌驾 public int getItemCount（）{ 返回mCardTypes.length； } @凌驾 public int getItemViewType（int位置）{ 返回mCardTypes[position]； }

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();
}

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];
}