android通讯录右侧字母导航的简单实现

接着上一篇文章,在已经分组排序好了的expandableListView界面加上导航的功能,因为刚学安卓不久,一开始还挺怕这玩意儿的,后来看了网上的几篇文章,再加上自己的思路,做好了之后一想,其实也没有多复杂,而且还挺简单的.先上完成后的效果图：

关于字母导航的在网上大概有两种实现方法：

1,使用button或image控件

2,画图

其实原理都差不多,本文在这里用的是画图的方式.

首先,自定义一个类继承android.view.View类

/** * 本类用来画出右侧的字母实现导航 * @author orathee */public class MyLetterView extends View {public SlideLetter mSlideLetter;private Paint paint ;private String[] sortKey = { "#", "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" };public MyLetterView(Context context) {super(context);}public MyLetterView(Context context, AttributeSet attrs, int defStyle) {super(context, attrs, defStyle);}public MyLetterView(Context context, AttributeSet attrs) {super(context, attrs);}@Overrideprotected void onDraw(Canvas canvas) {if(paint == null){paint = new Paint();}paint.setColor(Color.GRAY);paint.setTextSize(15);for (int i = 0; i < sortKey.length; i++) {canvas.drawText(sortKey[i], 8, 20 * (i + 1) + 100, paint);}super.onDraw(canvas);}@Overridepublic boolean onTouchEvent(MotionEvent event) {if(mSlideLetter == null){//获取contactsLayout的实例mSlideLetter = MainActivity.getmContactsLayout();}// 触发事件时获取当前坐标int y = (int) event.getY();//当前使用的是绝对坐标，对不不同机型待改进if (y >= 100 && y <= 640) {// 监听按下时的事件if (event.getAction() == MotionEvent.ACTION_DOWN) {mSlideLetter.showLetter();// 监听抬起的事件} else if (event.getAction() == MotionEvent.ACTION_UP) {mSlideLetter.hideLetter();}// 监听move的事件，text随着手势移动else if (event.getAction() == MotionEvent.ACTION_MOVE) {mSlideLetter.showLetter();}int number = (y - 105) / 20;String letter = sortKey[number];mSlideLetter.showToast(letter);invalidate();} else {mSlideLetter.hideLetter();}return true;}public interface SlideLetter {/** * 子母可见 */void showLetter();/** * 字母隐藏 */void hideLetter();/** * 显示子母 */void showToast(String letter);}}

本类主要是画出字母列和实现它的onTouch方法,另外SlideLetter接口需要实现它的三个方法

xml中view的配置：

<RelativeLayout        android:id="@+id/sort_layout"        android:layout_width="20dip"        android:layout_height="700dip"        android:layout_alignRight="@+id/expandableListView1" >        <com.out.view.MyLetterView            android:id="@+id/myView"            android:layout_width="fill_parent"            android:layout_height="fill_parent"            android:layout_alignParentLeft="true"            android:layout_alignParentTop="true" />    </RelativeLayout>

接口中三个方法的实现：

@Overridepublic void showLetter() {sectionToastLayout.setVisibility(View.VISIBLE);}@Overridepublic void hideLetter() {sectionToastLayout.setVisibility(View.GONE);}@Overridepublic void showToast(String letter) {sectionToastText.setText(letter);int position = adapter.getGroupPosition(letter);//获取需要显示字母的groupPositionif (position != -1) {exListView.setSelectedGroup(position);}}

这样就基本能够实现导航功能了,当然代码中还有很多的不足,比如：不能根据分辨率的大小适当的设置导航条的位置,还有待改进.