Android如何在自定义baseadapter中找到视图？

Question

我有一个几乎完成的自定义适配器，除了我想找到一个Tablelayout并以编程方式将每个子节点转换为单击侦听器。

    package com.mhsquire.adapter;

import android.app.Activity;
import android.content.Context;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.TableLayout;
import android.widget.TableRow;
import android.widget.TextView;
import android.widget.Toast;

import com.mhsquire.R;
import com.mhsquire.data.Constants;
import com.mhsquire.data.Product;

import java.util.ArrayList;
import java.util.List;

import butterknife.ButterKnife;
import butterknife.InjectViews;

//import butterknife.Views;

/**
 * Created by owner on 3/27/2015.
 */
public class FlippableProductAdapter extends BaseAdapter {

    private Activity activity;
    private String[] data;
    private LayoutInflater inflater = null;
    private ArrayList dataList = new ArrayList();
    private View targetView;
    private int repeatCount = 1;
    private static String TAG = "Product Adapter";
    private int mMaxIndex = 8;
    private int mIndexSize = 4;
    private static int mIndex = 0;

    @InjectViews({R.id.imgtxtProduct, R.id.imgtxtProductDescription})
    List<TextView> titleTexts;

    public FlippableProductAdapter(Activity a, String[] d) {
        activity = a;
        data = d;
        inflater = (LayoutInflater) activity.getSystemService(Context.LAYOUT_INFLATER_SERVICE);

        //imageLoader=new ImageLoader(activity.getApplicationContext());
    }

    public FlippableProductAdapter(Activity a) {
        activity = a;
        inflater = (LayoutInflater) activity.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    }

    public FlippableProductAdapter(Activity a, ArrayList target) {
        activity = a;
        inflater = (LayoutInflater) activity.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        dataList = target;

        inflater = LayoutInflater.from(a.getBaseContext());
    }


    private void initializeProductList(ViewHolder holder) {
        for (int i = 0; i < mMaxIndex; i = i + 2) {
            if (mIndex + i / 2 < Constants.ALLPRODUCTS.size() && !Constants.ALLPRODUCTS.isEmpty()) {
                holder.textViews.get(i).setText(Constants.ALLPRODUCTS.get(mIndex + i / 2).getProductname());
                holder.textViews.get(i + 1).setText(Constants.ALLPRODUCTS.get(mIndex + i / 2).getProductDescription());
            } else {
                holder.textViews.get(i).setText("");
                holder.textViews.get(i + 1).setText("");
            }
        }
    }

    View.OnClickListener onClick(final TableRow row, final int col) {
        return new View.OnClickListener() {
            public void onClick(View v) {
                int position = v.getId();
                Log.i(TAG, "Clicked Item " + Constants.PRODUCTINDEX);
                if (Constants.INDEX + position < Constants.ALLPRODUCTS.size()) {
                    titleTexts.get(0).setText(Constants.ALLPRODUCTS.get(Constants.INDEX + position).getProductname());
                    titleTexts.get(1).setText(Constants.ALLPRODUCTS.get(Constants.INDEX + position).getProductDescription());
                }

            }
        };
    }

    public static class ViewHolder {

        public ViewHolder(View view) {
            ButterKnife.inject(this, view);
        }
    }

    public View getView(int position, View convertView, ViewGroup parent) {
        View vi = convertView;
        ViewHolder holder;
        final int toofar = 2;


            Constants.FUTUREPOSITION = position;

        mIndex = Constants.FUTUREPOSITION * mIndexSize;

        if (convertView == null) {
            vi = inflater.inflate(R.layout.activity_main_flippable, null);
            holder = new ViewHolder(vi);
            vi.setTag(holder);
        } else holder = (ViewHolder) vi.getTag();

        Product target = (Product) dataList.get(position);

        initializeProductList(holder);

        TableRow row;
        TableLayout group = (TableLayout) activity.findViewById(R.id.TableLayout); // NullPointerException Here
        for (int i = 0; i < group.getChildCount(); i++)
        {
            row = (TableRow) group.getChildAt(i);
            activity.registerForContextMenu(row);
            row.setId(i);
            row.setOnClickListener(onClick(row, i));
        }


        return vi;
    }

}

现在我的问题是我在上面的行收到NullPointerException。识别TableLayout的正确方法是什么？

Answer 1

尝试用group视图替换parent：

TableRow row;

for (int i = 0; i < parent.getChildCount(); i++)
{
    row = (TableRow) parent.getChildAt(i);
    activity.registerForContextMenu(row);
    row.setId(i);
    row.setOnClickListener(onClick(row, i));
}

Answer 2

创建一个名为ViewHolder的类，将代码和OnClck（）放在这样：

    public static class ViewHolder {

        public ViewHolder(View view) {
            ButterKnife.inject(this, view);

            TableRow row;
            TableLayout group = (TableLayout)  
            view.findViewById(R.id.TableLayout); // NullPointerException Here
            for (int i = 0; i < group.getChildCount(); i++)
            {
                row = (TableRow) group.getChildAt(i);
                activity.registerForContextMenu(row);
                row.setId(i);
                row.setOnClickListener(onClick(row, i));
            }
        }

        View.OnClickListener onClick(final TableRow row, final int col) {
            return new View.OnClickListener() {
                public void onClick(View v) {
                    int position = v.getId();
                    Log.i(TAG, "Clicked Item " + Constants.PRODUCTINDEX);
                    if (Constants.INDEX + position < Constants.ALLPRODUCTS.size()) {
                    titleTexts.get(0).setText(Constants.ALLPRODUCTS.get(Constants.INDEX + position).getProductname());
                    titleTexts.get(1).setText(Constants.ALLPRODUCTS.get(Constants.INDEX + position).getProductDescription());
                }

            }
        };
    }
    }

GetView将视图传递给ViewHolder，后者可以操纵子视图。

    public View getView(int position, View convertView, ViewGroup parent) {
        View vi = convertView;
        ViewHolder holder;
        final int toofar = 2;


            Constants.FUTUREPOSITION = position;

        mIndex = Constants.FUTUREPOSITION * mIndexSize;

        if (convertView == null) {
            vi = inflater.inflate(R.layout.activity_main_flippable, null);
            holder = new ViewHolder(vi);
            vi.setTag(holder);
        } else holder = (ViewHolder) vi.getTag();

        Product target = (Product) dataList.get(position);

        initializeProductList(holder);




        return vi;
    }

}