android 按字母搜索

在看Oplayer的时候看见滑动字母来实现listView的内容搜索，所以就把里面的核心的函数扣除来做了一个demo,分为两部分一个是布局，另一个就是代码了，具体的如下：

布局：

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="fill_parent"    android:layout_height="fill_parent"    android:layout_weight="1.0"    android:orientation="horizontal" >    <FrameLayout        android:layout_width="0dip"        android:layout_height="fill_parent"        android:layout_weight="1.0"        android:orientation="vertical" >        <ListView            android:id="@+id/list"            android:layout_width="fill_parent"            android:layout_height="fill_parent"            android:cacheColorHint="@android:color/transparent"            android:divider="@drawable/ic_line"            android:drawSelectorOnTop="false"            android:fadingEdge="none"            android:listSelector="@android:color/transparent"            android:scrollbars="none" />        <TextView            android:id="@+id/first_letter_overlay"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:layout_gravity="right"            android:layout_marginRight="50.0dip"            android:layout_marginTop="49.0dip"            android:background="@drawable/fast_scroller_overlay"            android:gravity="center"            android:paddingBottom="5.0dip"            android:scaleType="center"            android:textSize="43.0dip"            android:visibility="gone" />    </FrameLayout>    <ImageView        android:id="@+id/alphabet_scroller"        android:layout_width="wrap_content"        android:layout_height="match_parent"        android:layout_gravity="center"        android:paddingRight="0dip"        android:scaleType="fitXY"        android:src="@drawable/alphabet_scroller_bg" /></LinearLayout>

里面涉及到了一个ImageView的图片

<?xml version="1.0" encoding="UTF-8"?><selector  xmlns:android="http://schemas.android.com/apk/res/android">    <item android:state_pressed="true" android:drawable="@drawable/contact_list_scroll_pressed" />    <item android:drawable="@drawable/contact_list_scroll_normal" /></selector>

具体的代码如下:

package com.example.test;import java.util.ArrayList;import java.util.List;import android.app.Activity;import android.os.Bundle;import android.util.Log;import android.view.MotionEvent;import android.view.View;import android.view.ViewGroup;import android.view.View.OnTouchListener;import android.widget.BaseAdapter;import android.widget.ImageView;import android.widget.ListView;import android.widget.TextView;public class Main6 extends Activity{ListView iListView;TextView showChar;ImageView myChar;List<String> iList;MAdapter mAdapter;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.main5);iListView = (ListView)findViewById(R.id.list);showChar = (TextView)findViewById(R.id.first_letter_overlay);myChar = (ImageView)findViewById(R.id.alphabet_scroller);iList = initChar();Log.e("t", " "+iList.size());mAdapter = new MAdapter();iListView.setAdapter(mAdapter);myChar.setClickable(true);myChar.setOnTouchListener(asOnTouch);}/** * A-Z */private OnTouchListener asOnTouch = new OnTouchListener() {@Overridepublic boolean onTouch(View v, MotionEvent event) {switch (event.getAction()) {case MotionEvent.ACTION_DOWN:// 0myChar.setPressed(true);showChar.setVisibility(View.VISIBLE);mathScrollerPosition(event.getY());break;case MotionEvent.ACTION_UP:// 1myChar.setPressed(false);showChar.setVisibility(View.GONE);break;case MotionEvent.ACTION_MOVE:mathScrollerPosition(event.getY());break;}return false;}};/** * 显示字符 *  * @param y */private void mathScrollerPosition(float y) {int height = myChar.getHeight();float charHeight = height / 28.0f;char c = 'A';if (y < 0)y = 0;else if (y > height)y = height;int index = (int) (y / charHeight) - 1;if (index < 0)index = 0;else if (index > 25)index = 25;String key = String.valueOf((char) (c + index));showChar.setText(key);int position = 0;if (index == 0)iListView.setSelection(0);else if (index == 25)iListView.setSelection(mAdapter.getCount() - 1);else {if (mAdapter != null) {for (int i = 0; i < iList.size(); i++) {if (iList.get(i).startsWith(key)) {iListView.setSelection(position);break;}position++;}}}}/** * ListView的数据 * @return */public List<String> initChar(){List<String> list = new ArrayList<String>();char c = 'A';for (int i = 0; i < 26; i++) {list.add(String.valueOf((char) (c + i)));list.add(String.valueOf((char) (c + i)));list.add(String.valueOf((char) (c + i)));}return list;}class MAdapter extends BaseAdapter{@Overridepublic int getCount() {return iList.size();}@Overridepublic Object getItem(int position) {return iList.get(position);}@Overridepublic long getItemId(int position) {return position;}@Overridepublic View getView(int position, View convertView, ViewGroup parent) {TextView text = new TextView(getApplicationContext());text.setText(iList.get(position));return text;}}}

为了方便我就用了字母来填充listView，其实原理是很简单的。具体的显示如下：

android 按字母搜索

拖动后的显示效果：

android 按字母搜索

里面使用的那两张图片也发出来

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