今天我们用ListView+自定义组件SlideBar来实现城市的快速索引(当然其他相似的功能也是一样的)，虽然网上已经有很多大神做出来了，也更加的丰富，但我还是做一个小demo来练习巩固一下，毕竟多动动手总没坏处是吧，哈哈，先看效果图吧
看了效果图后我们就开始实现吧，其实也是很简单的(卧槽，图怎么这么大 =。=)
先是我们的布局文件，整体非常简单的布局：
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"android:orientation="vertical"android:layout_width="match_parent"android:layout_height="match_parent"><FrameLayoutandroid:id="@+id/city_loacal"android:layout_width="match_parent"android:layout_height="wrap_content"><ListViewandroid:id="@+id/city_rv"android:layout_width="match_parent"android:layout_height="wrap_content"/><TextViewandroid:id="@+id/float_letter"android:layout_width="80dp"android:layout_height="80dp"android:layout_gravity="center"android:background="#dcdcdc"android:gravity="center"android:textSize="40sp"android:visibility="gone" /><com.cn.listviewsliderbar.SlideBarandroid:id="@+id/slidebar"android:layout_width="23dp"android:background="#dcdcdc"android:layout_height="wrap_content"android:layout_gravity="right|bottom" /></FrameLayout>
</LinearLayout>
布局就是这么简单，然后是我们的Activity的代码:
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.ListView;
import android.widget.TextView;/***/
public class CityActivty extends Activity implements SlideBar.OnTouchLetterChangeListenner{CityListAdapter mAdapter;TextView float_letter;ListView cityList;SlideBar slideBar;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_city);mAdapter = new CityListAdapter(this);cityList= (ListView) findViewById(R.id.city_rv);float_letter = (TextView) findViewById(R.id.float_letter);slideBar= (SlideBar) findViewById(R.id.slidebar);
// cityRv.addHeaderView(v);cityList.setAdapter(mAdapter);slideBar.setOnTouchLetterChangeListenner(this);}@Overridepublic void onTouchLetterChange(boolean isTouched, String s) {float_letter.setText(s);if (isTouched) {float_letter.setVisibility(View.VISIBLE);} else {float_letter.postDelayed(new Runnable() {@Overridepublic void run() {float_letter.setVisibility(View.GONE);}}, 100);}int moveToPosition = mAdapter.getPositionForSection(s.charAt(0));if (moveToPosition >= 0) {cityList.setSelectionFromTop(moveToPosition, 0);}}
}OnTouchLetterChangeListener是我们SlideBar里面定义的接口，是SlideBar的滑动与listView相关联的监听方法，我们通过实现它的方法onTouchLetterChange来调用ListView的setSelectionFromTop来完成索引功能。
下面是Adapter的代码：
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.SectionIndexer;
import android.widget.TextView;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
import java.util.Locale;public class CityListAdapter extends BaseAdapter implements SectionIndexer{Context context;List<CityEntity> data=getCityList();public CityListAdapter(Context context) {this.context = context;}@Overridepublic int getCount() {return data.size();}@Overridepublic View getView(int position, View convertView, ViewGroup parent) {CityViewHolder_2 holder_2 = null;if (convertView == null){holder_2=new CityViewHolder_2();convertView= LayoutInflater.from(context).inflate(R.layout.item_listview_city,null);holder_2.word_tv= (TextView) convertView.findViewById(R.id.city_word_tv);holder_2.city_tv= (TextView) convertView.findViewById(R.id.city_list_tv);convertView.setTag(holder_2);}else{holder_2= (CityViewHolder_2) convertView.getTag();}holder_2.city_tv.setText(getCityList().get(position).getCityname());holder_2.word_tv.setText(getFirstChar(getCityList().get(position).getWord()));int section = getSectionForPosition(position);int sectionPos = getPositionForSection(section);if(position == sectionPos) {holder_2.word_tv.setVisibility(View.VISIBLE);} else {holder_2.word_tv.setVisibility(View.GONE);}return convertView;}private String getFirstChar(String sortKey) {return sortKey.substring(0, 1).toUpperCase(Locale.CHINA);}@Overridepublic Object[] getSections() {return new Object[0];}@Overridepublic int getPositionForSection(int sectionIndex) {int position = -1;for (int i = 0; i < data.size(); i++) {int currentChar = getSectionForPosition(i);if(currentChar == sectionIndex) {position = i;break;}}return position;}@Overridepublic int getSectionForPosition(int position) {return data.get(position).getWord().toUpperCase(Locale.CHINA).charAt(0);}class CityViewHolder_2{TextView word_tv,city_tv;}@Overridepublic Object getItem(int position) {return null;}@Overridepublic long getItemId(int position) {return position;}public List<CityEntity> getCityList(){List<CityEntity> data=new ArrayList<CityEntity>();data.add(new CityEntity("成都","chengdu"));data.add(new CityEntity("成都","chengdu"));data.add(new CityEntity("成都","chengdu"));data.add(new CityEntity("成都","chengdu"));data.add(new CityEntity("成都","chengdu"));data.add(new CityEntity("郑州","zhengzhou"));data.add(new CityEntity("郑州","zhengzhou"));data.add(new CityEntity("郑州","zhengzhou"));data.add(new CityEntity("金华","jinhua"));data.add(new CityEntity("金华","jinhua"));data.add(new CityEntity("成都","chengdu"));data.add(new CityEntity("成都","chengdu"));data.add(new CityEntity("金华","jinhua"));data.add(new CityEntity("金华","jinhua"));data.add(new CityEntity("金华","jinhua"));data.add(new CityEntity("郑州","zhengzhou"));data.add(new CityEntity("郑州","zhengzhou"));data.add(new CityEntity("郑州","zhengzhou"));data.add(new CityEntity("郑州","zhengzhou"));data.add(new CityEntity("郑州","zhengzhou"));data.add(new CityEntity("金华","jinhua"));data.add(new CityEntity("金华","jinhua"));data.add(new CityEntity("成都","chengdu"));data.add(new CityEntity("成都","chengdu"));data.add(new CityEntity("成都","chengdu"));data.add(new CityEntity("郑州","zhengzhou"));data.add(new CityEntity("郑州","zhengzhou"));data.add(new CityEntity("金华","jinhua"));data.add(new CityEntity("金华","jinhua"));data.add(new CityEntity("金华","jinhua"));Collections.sort(data, new Comparator<CityEntity>() {@Overridepublic int compare(CityEntity lhs, CityEntity rhs) {return lhs.getWord().compareTo(rhs.getWord());}});return data;}
}这个里面的重点是SectionIndexer这个接口，我们一般的索引都会用到这个接口，这个接口它主要实现了两个方法是：
getSectionForPosition()和getPositionForSection() ，前者是根据位置找索引号，后者是根据索引号找位置，具体的不同大家可以参考一下博客：http://blog.csdn.net/jack_l1/article/details/14165291
到这里我们这个功能的具体实现就这么多了，因为功能还是比较单一的，所以代码量也不是很多，SlideBar的代码会和源码一起给大家o(^▽^)o
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源码下载地址：http://download.csdn.net/detail/tobestrong_csdn/9594317