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;

	@Override

	protected 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() {



		@Override

		public boolean onTouch(View v, MotionEvent event) {

			switch (event.getAction()) {

			case MotionEvent.ACTION_DOWN:// 0

				myChar.setPressed(true);

				showChar.setVisibility(View.VISIBLE);

				mathScrollerPosition(event.getY());

				break;

			case MotionEvent.ACTION_UP:// 1

				myChar.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{



		@Override

		public int getCount() {

			return iList.size();

		}



		@Override

		public Object getItem(int position) {

			return iList.get(position);

		}



		@Override

		public long getItemId(int position) {

			return position;

		}



		@Override

		public 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：

 

拖动后的显示效果：

里面使用的那两张图片也发出来