import com.hiapk.market.R;import android.content.Context;import android.graphics.PixelFormat;import android.os.Handler;import android.view.LayoutInflater;import android.view.View;import android.view.WindowManager;import android.view.WindowManager.LayoutParams;import android.widget.TextView;/** * 窗口中間顯示半透明提示框的小組件 * 用法：1. new 2. showPrevLetter(String prevLetter) * @author LL * */public class PrevLetterDialog {  //窗體消失的延時時間  private static final int DELAYED_HIDEN = 500;  // 實現Runnable接口的類  private RemoveWindow mRemoveWindow = new RemoveWindow();  //在Handler里能實現對UI線程的修改  private Handler mHandler;  //窗體管理器  private WindowManager mWindowManager;  //顯示在窗體中間半透明的字體框  private TextView mDialogText;  //是否正在顯示中  private boolean mShowing;  //是否準備好顯示了  private boolean mReady;  //顯示在窗體中的字符  private char mPrevLetter = Character.MIN_VALUE;  /**   * 注明：context一定要在可見UI中通過getContext()獲得，否則會拋異常。   * @param context   */  public PrevLetterDialog(Context context) {    //得到窗體管理器    mWindowManager = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);    //得到布部創建者    LayoutInflater inflate = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);    //得到TextView    mDialogText = (TextView) inflate.inflate(R.layout.list_position, null);    //設TextView為可見    mDialogText.setVisibility(View.INVISIBLE);    //通過handler把mDialogText展示出來    mHandler = new Handler();    //要用post可實現在多線程里調用UI線程并改變    mHandler.post(new Runnable() {      public void run() {        mReady = true;        //窗體的布局參數        WindowManager.LayoutParams lp = new WindowManager.LayoutParams(LayoutParams.WRAP_CONTENT,            LayoutParams.WRAP_CONTENT, WindowManager.LayoutParams.TYPE_APPLICATION,            WindowManager.LayoutParams.FLAG_NOT_TOUCHABLE | WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE,            PixelFormat.TRANSLUCENT);        //把TextView添加到窗體中去        mWindowManager.addView(mDialogText, lp);      }    });  }  //設置可見性  public void setmReady(boolean mReady) {    this.mReady = mReady;  }  /**   * 一般用在onScroll方法中,參數是字符串，不能為空，會取第一個字符顯示   * @param prevLetter   */  public void showPrevLetter(String prevLetter) {    if (!mReady) {      return;    }    char firstLetter = prevLetter.charAt(0);    if (!mShowing && firstLetter != mPrevLetter) {      mShowing = true;      mDialogText.setVisibility(View.VISIBLE);    }    //設TextView顯示的字體    mDialogText.setText(((Character) firstLetter).toString());    //移除mRemoveWindow實現的Runnable接口類    mHandler.removeCallbacks(mRemoveWindow);    //添加mRemoveWindow實現的Runnable接口類，并設延時    mHandler.postDelayed(mRemoveWindow, DELAYED_HIDEN);    mPrevLetter = firstLetter;  }  /**   * 實現Runnable接口的類   */  private final class RemoveWindow implements Runnable {    public void run() {      removeWindow();    }  }  private void removeWindow() {    if (mShowing) {      mShowing = false;      mDialogText.setVisibility(View.INVISIBLE);    }  }}

<?xml version="1.0" encoding="utf-8"?><TextView xmlns:android="http://schemas.android.com/apk/res/android"  android:textSize="50sp"  android:textColor="@color/band_common_content"  android:background="@drawable/common_list_title"  android:minWidth="70dip"  android:layout_height="wrap_content"  android:padding="5dip"  android:gravity="center"/>