Android开发之自定义view实现通讯录列表A~Z字母提示效果【附demo源码下载】

public class MyLetterListView extends View {  OnTouchingLetterChangedListener onTouchingLetterChangedListener;  String[] b = {"#","A","B","C","D","E","F","G","H","I","J","K","L"      ,"M","N","O","P","Q","R","S","T","U","V","W","X","Y","Z"};  int choose = -1;  Paint paint = new Paint();  boolean showBkg = false;  public MyLetterListView(Context context, AttributeSet attrs, int defStyle) {    super(context, attrs, defStyle);  }  public MyLetterListView(Context context, AttributeSet attrs) {    super(context, attrs);  }  public MyLetterListView(Context context) {    super(context);  }  @Override  protected void onDraw(Canvas canvas) {    super.onDraw(canvas);    if(showBkg){      canvas.drawColor(Color.parseColor("#40000000"));    }    int height = getHeight();    int width = getWidth();    int singleHeight = height / b.length;    for(int i=0;i<b.length;i++){      paint.setColor(Color.WHITE);      paint.setTypeface(Typeface.DEFAULT_BOLD);      paint.setAntiAlias(true);      if(i == choose){        paint.setColor(Color.parseColor("#3399ff"));        paint.setFakeBoldText(true);      }      float xPos = width/2 - paint.measureText(b[i])/2;      float yPos = singleHeight * i + singleHeight;      canvas.drawText(b[i], xPos, yPos, paint);      paint.reset();    }  }  @Override  public boolean dispatchTouchEvent(MotionEvent event) {    final int action = event.getAction();    final float y = event.getY();    final int oldChoose = choose;    final OnTouchingLetterChangedListener listener = onTouchingLetterChangedListener;    final int c = (int) (y/getHeight()*b.length);    switch (action) {      case MotionEvent.ACTION_DOWN:        showBkg = true;        if(oldChoose != c && listener != null){          if(c > 0 && c< b.length){            listener.onTouchingLetterChanged(b[c]);            choose = c;            invalidate();          }        }        break;      case MotionEvent.ACTION_MOVE:        if(oldChoose != c && listener != null){          if(c > 0 && c< b.length){            listener.onTouchingLetterChanged(b[c]);            choose = c;            invalidate();          }        }        break;      case MotionEvent.ACTION_UP:        showBkg = false;        choose = -1;        invalidate();        break;    }    return true;  }  @Override  public boolean onTouchEvent(MotionEvent event) {    return super.onTouchEvent(event);  }  public void setOnTouchingLetterChangedListener(      OnTouchingLetterChangedListener onTouchingLetterChangedListener) {    this.onTouchingLetterChangedListener = onTouchingLetterChangedListener;  }  public interface OnTouchingLetterChangedListener{    public void onTouchingLetterChanged(String s);  }}

private class LetterListViewListener implements OnTouchingLetterChangedListener{    @Override    public void onTouchingLetterChanged(final String s) {      if(alphaIndexer.get(s) != null) {        int position = alphaIndexer.get(s);        personList.setSelection(position);        overlay.setText(sections[position]);        overlay.setVisibility(View.VISIBLE);        handler.removeCallbacks(overlayThread);        //延迟一点五秒后执行，让overlay为不可见        handler.postDelayed(overlayThread, 1500);      }    }}

//设置overlay不可见private class OverlayThread implements Runnable {    @Override    public void run() {      overlay.setVisibility(View.GONE);    }}

//获得汉语拼音首字母private String getAlpha(String str) {    if (str == null) {      return "#";    }    if (str.trim().length() == 0) {      return "#";    }    char c = str.trim().substring(0, 1).charAt(0);    // 正则表达式，判断首字母是否是英文字母    Pattern pattern = Pattern.compile("^[A-Za-z]+{1}quot;);    if (pattern.matcher(c + "").matches()) {      return (c + "").toUpperCase();    } else {      return "#";    }}