ListView之getView易错点

最新推荐文章于 2021-05-28 15:39:16 发布

原创最新推荐文章于 2021-05-28 15:39:16 发布 · 671 阅读

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本文介绍了一个具体的Android应用案例，展示了如何使用ListView展示大量数据，并通过ViewHolder模式减少内存消耗，提高滚动性能。文章详细解释了自定义BaseAdapter的过程，包括getView方法中对convertView的复用，以确保在滚动列表时不会频繁创建新的视图。

直接上代码：

package com.antest;

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

import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ListView;
import android.widget.TextView;

public class MainActivity extends Activity {
	private List<String> list;

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

		list = new ArrayList<String>();
		for (int i = 0; i < 100; i++) {
			list.add(i + "");
		}

		ListView list = (ListView) findViewById(R.id.list);
		list.setAdapter(adapter);
	}

	BaseAdapter adapter = new BaseAdapter() {

		@Override
		public int getCount() {
			return 100;
		}

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

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

		@Override
		public View getView(int position, View convertView, ViewGroup parent) {
			Holder holder;
			if (convertView == null) {
				holder = new Holder();
				convertView = LayoutInflater.from(getApplicationContext()).inflate(R.layout.list_item, null);
				holder.tv = (TextView) convertView.findViewById(R.id.tv);
				convertView.setTag(holder);
				Log.i("lk", position + "");
			} else {
				holder = (Holder) convertView.getTag();
			}
			holder.tv.setText(getItem(position).toString());
			return convertView;
		}

	};

	class Holder {
		TextView tv;
	}

}

手机屏幕显示：

输出：

05-13 16:28:18.563: I/lk(21641): 0
05-13 16:28:18.563: I/lk(21641): 1
05-13 16:28:18.563: I/lk(21641): 2
05-13 16:28:18.563: I/lk(21641): 3
05-13 16:28:18.563: I/lk(21641): 4
05-13 16:28:18.563: I/lk(21641): 5
05-13 16:28:18.573: I/lk(21641): 6
05-13 16:28:18.573: I/lk(21641): 7
05-13 16:28:18.573: I/lk(21641): 8
05-13 16:28:18.573: I/lk(21641): 9
05-13 16:28:18.573: I/lk(21641): 10
05-13 16:28:18.573: I/lk(21641): 11
05-13 16:28:18.573: I/lk(21641): 12
05-13 16:28:18.573: I/lk(21641): 13
05-13 16:28:18.573: I/lk(21641): 14
05-13 16:28:18.573: I/lk(21641): 15
05-13 16:28:18.573: I/lk(21641): 16
05-13 16:28:18.573: I/lk(21641): 17
05-13 16:28:18.583: I/lk(21641): 18
05-13 16:28:18.583: I/lk(21641): 19
05-13 16:28:18.583: I/lk(21641): 20
05-13 16:28:18.583: I/lk(21641): 21
05-13 16:28:18.583: I/lk(21641): 22
05-13 16:28:18.583: I/lk(21641): 23