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1、ListView的一个经典实现动态增加、删除行的例子实现。
2、Listview优化策略?
1)convetView进行判空,为空时加载布局,不为空时直接重新使用 convertView,减少了布局的加载。(效率提高200%)
2)定义ViewHolder,传入ViewHolder对象给convetView设置tag,用于缓存控件。(效率再提高50%) 3)当ListView加载数据量较大时可采用分页加载和图片异步加载方法。3、代码示例
0.data.java
package com.guan.http.model;public class Data { private int id; private ImageView image; private int num; public Data() { super(); } public Student(int id, ImageView image, int num) { super(); this.id = id; this.image = image; this.num = num; } public int getId() { return id; } public void setId(int id) { this.id = id; } public String getImage() { return image; } public void setName(String image) { this.image = image; } public int getNum() { return num; } public void setNum(int num) { this.num = num; }}
①activity_main.xml
②adater_line.xml
③ShowAdapter
package com.example.guan.adapter;import android.content.Context;import android.view.LayoutInflater;import android.view.View;import android.view.ViewGroup;import android.widget.BaseAdapter;import android.widget.ImageView;import android.widget.TextView;import com.example.guan.listview.R;import java.util.List;import butterknife.ButterKnife;import butterknife.InjectView;/** * @author Guan * @file com.example.guan.adapter * @date 2015/8/14 * @Version 1.0 */public class ShowAdapter extends BaseAdapter { private Context mContext; private List mList; public ShowAdapter(Context context, List list) { this.mContext = context; this.mList = list; } @Override public int getCount() { if (mList != null && mList.size() > 0) { return mList.size(); } else { return 0; } } @Override public Object getItem(int position) { if (mList != null && mList.size() > 0) { return mList.get(position); } else { return null; } } @Override public long getItemId(int position) { return position; } @Override public View getView(int position, View convertView, ViewGroup parent) { // 2、使用了ViewHolder作为子布局的缓存,使用View的setTag方法将缓存与每个item绑定, // 则也可以省去了findViewById的事件 ViewHolder holder; if (convertView != null) { // 3、获取ViewHolder holder = (ViewHolder) convertView.getTag(); } else { convertView = LayoutInflater.from(mContext).inflate(R.layout.adater_line, null); holder = new ViewHolder(convertView); convertView.setTag(holder); } // 获取数据对象 Data data = (Data) getItem(position); // 4、绑定数据到holder. holder.textView.setText(data.getNum() + ""); //holder.textView.setText(mList.get(position).toString()); return convertView; } /** * 1、将ViewHolder设置为static的目的是指在初始化Adapter时初始化一次这个内部类, * 否则将会在每次创建Adapter时都要初始化一次,而这是没有必要的。 */ static class ViewHolder { @InjectView(R.id.imageView) ImageView imageView; @InjectView(R.id.textView) TextView textView; ViewHolder(View view) { ButterKnife.inject(this, view); } }}
④MainActivity
package com.example.guan.listview;import android.os.Bundle;import android.support.v7.app.AppCompatActivity;import android.view.View;import android.widget.Button;import android.widget.ListView;import android.widget.Toast;import com.example.guan.adapter.ShowAdapter;import java.util.ArrayList;import java.util.List;import butterknife.ButterKnife;import butterknife.InjectView;import butterknife.OnClick;/** * @author Guan * @file com.example.guan.listviews * @date 2015/8/14 * @Version 1.0 */public class MainActivity extends AppCompatActivity { @InjectView(R.id.btn_add) Button btnAdd; @InjectView(R.id.btn_remove) Button btnRemove; @InjectView(R.id.lv_show) ListView lvShow; private List list; private ShowAdapter showAdapter; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); ButterKnife.inject(this); // 初始化 Init(); } /** * 初始化 */ private void Init() { list = new ArrayList(); for (int i = 0; i < 3; i++) { list.add("123"); } showAdapter = new ShowAdapter(this, list); lvShow.setAdapter(showAdapter); } /** * 监听实现 * @param view */ @OnClick({R.id.btn_add, R.id.btn_remove}) public void pickDoor(View view) { if (view == btnAdd) { list.add("123"); showAdapter.notifyDataSetChanged(); } else { list.remove(0); showAdapter.notifyDataSetChanged(); } }}
⑤图片资源
4、效果图
5、知识补充
1)adapter.notifyDataSetChanged()
①实现对listView列表的刷新; ②新建一个集合时,adapter调用此方法时强制传到getView执行。2)布局
android:divider 边框线条 = “#FFFFFF”/ “@drawable/list” android:dividerHeight 边框线条3)去除分割线
①设置android:divider="@null" ②android:divider="#00000000" #00000000后面两个零表示透明 ③.setDividerHeight(0) 高度设为04)去除滚动棒
android:scrollbars=“none”转载地址:http://mmcub.baihongyu.com/