测试 ListView 的效率 3 [原创]

继续前面的测试,

package cn.powerise.test01;

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

import android.app.ListActivity;
import android.content.Context;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.TextView;

/**
 * 测试 ListView 的效率
 * @author R9(QQ:34351088)
 */
public class List_Efficiency_3 extends ListActivity {

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        List<HashMap<String, Object>> data = null;
        MyAdapter adapter = null;

        data = getData();

        adapter = new MyAdapter(this, data, R.layout.efficiency_item);
        setListAdapter(adapter);
    }

    private List<HashMap<String, Object>> getData() {
        List<HashMap<String, Object>> data = null;
        HashMap<String, Object> item = null;

        data = new ArrayList<HashMap<String, Object>>();
        for (int i = 10; i < 40; i++) {
            item = new HashMap<String, Object>();
            item.put("image", R.drawable.icon);
            item.put("id", i);
            item.put("name", "Name" + i);
            item.put("age", "Age" + i);
            item.put("phone", "139073100" + i);
            data.add(item);
        }

        return data;
    }

    static class ViewHolder {
        ImageView imageView;
        TextView idTextView;
        TextView nameTextView;
        TextView ageTextView;
        TextView phoneTextView;
    }

    class MyAdapter extends BaseAdapter {

        private List<HashMap<String, Object>> mData;
        private LayoutInflater mInflater;
        private int mResource;

        public MyAdapter(Context context, List<HashMap<String, Object>> data, int resource) {
            mData = data;
            mResource = resource;
            mInflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        }

        @Override
        public View getView(int position, View convertView, ViewGroup parent) {

            ViewHolder holder;

            /**
             * 测试效率(改进)
             */
            if (convertView == null) {
                convertView = mInflater.inflate(mResource, null);
                holder = new ViewHolder();
                System.out.println("-->" + position);
                holder.imageView = (ImageView) convertView.findViewById(R.id.iv_image);
                holder.idTextView = (TextView) convertView.findViewById(R.id.txt_id);
                holder.nameTextView = (TextView) convertView.findViewById(R.id.txt_name);
                holder.ageTextView = (TextView) convertView.findViewById(R.id.txt_age);
                holder.phoneTextView = (TextView) convertView.findViewById(R.id.txt_phone);
                convertView.setTag(holder);
            } else {
                holder = (ViewHolder) convertView.getTag();
            }

            HashMap<String, Object> dataSet = mData.get(position);

            holder.imageView.setImageResource(R.drawable.icon);
            holder.idTextView.setText(dataSet.get("id").toString());
            holder.nameTextView.setText(dataSet.get("name").toString());
            holder.ageTextView.setText(dataSet.get("age").toString());
            holder.phoneTextView.setText(dataSet.get("phone").toString());

            return convertView;
        }

        @Override
        public int getCount() {
            return mData.size();
        }

        @Override
        public Object getItem(int position) {
            return mData.get(position);
        }

        @Override
        public long getItemId(int position) {
            return position;
        }

    }
}

布局文件同前. 

本测试, 与前面不同之处在于, 添加了如下代码:

static class ViewHolder {
　　ImageView imageView;
　　TextView idTextView;
　　TextView nameTextView;
　　TextView ageTextView;
　　TextView phoneTextView;
}

修改了 getView 的代码:

@Override
public View getView(int position, View convertView, ViewGroup parent) {

　　ViewHolder holder;

　　/**
　　* 测试效率(改进)
　　*/
　　if (convertView == null) {
　　　　convertView = mInflater.inflate(mResource, null);
　　　　holder = new ViewHolder();
　　　　System.out.println("-->" + position);
　　　　holder.imageView = (ImageView) convertView.findViewById(R.id.iv_image);
　　　　holder.idTextView = (TextView) convertView.findViewById(R.id.txt_id);
　　　　holder.nameTextView = (TextView) convertView.findViewById(R.id.txt_name);
　　　　holder.ageTextView = (TextView) convertView.findViewById(R.id.txt_age);
       holder.phoneTextView = (TextView) convertView.findViewById(R.id.txt_phone);
　　　　convertView.setTag(holder);

　　} else {
　　　　holder = (ViewHolder) convertView.getTag();
　　}

　　HashMap<String, Object> dataSet = mData.get(position);

　　holder.imageView.setImageResource(R.drawable.icon);
　　holder.idTextView.setText(dataSet.get("id").toString());
　　holder.nameTextView.setText(dataSet.get("name").toString());
　　holder.ageTextView.setText(dataSet.get("age").toString());
　　holder.phoneTextView.setText(dataSet.get("phone").toString());

　　return convertView;
}

这样做的目的是更进一步提高效率, 减少 findViewById.

小结: 自定义 Adapter extends BaseAdapter

1. 获取 convertView.

2. 获取 convertView 中的每个组件.

3. 手动对每个组件进行赋值.

至于什么 ListView + CheckBox, ListView + RadioButton, 也是如此, 在此就不再多述了.