安卓学习37
今天学习了安卓的一些知识其中主要的是：
Android数组排序常见方法
122.
Android的数组排序方式基本上使用了Sun原生的Java API实现，常用的有Comparator接口实现compare方法和
Comparable接口的compareTo方法，我们对于一个数组列表比如
ArrayList可以通过这两个接口进行排序和比较，这里Android123给大家一个例子
123.
124.
private final Comparator cwjComp arator = new Comparator() { private final Collator collator = Colla tor.getInstance();
125. public final int compare(Object a, Object b) {
126. CharSequence a = ((Item) a).sName;
127. CharSequence b = ((Item) b).sID;
128. return http://www.doczj.com/doc/ca10c5fc6037ee06eff9aef8941ea76e58fa4a08.htmlpare(a, b);
129. }
130. };
Android系统的进度条控件默认的设计的不是很周全，比如没有包含文字的显示，那么如何在Android进度条控件上显示文字呢? 来自Google内部的代码来了解下，主要使用的addView这样的方法通过覆盖一层Chronometer秒表控件来实现，整个代码如下
135.
public class TextProgressBar ext ends RelativeLayout implements OnChronometerTickListener {
136. public static final String TAG = "TextProgressBar";
137. static final int CHRONOMETER_ID = android.R.id.text1; 138. static final int PROGRESSBAR_ID = android.R.id.progress; 139. Chronometer mChronometer = null;
140. ProgressBar mProgressBar = null;
141. long mDurationBase = -1;
142. int mDuration = -1; boolean mChronometerFollow = false; 143. int mChronometerGravity = Gravity.NO_GRAVITY;
144. public TextProgressBar(Context context, AttributeSet attrs, int d efStyle) {
145. super(context, attrs, defStyle);
146. } public TextProgressBar(Context context, AttributeSet attrs) {
147. super(context, attrs);
148. } public TextProgressBar(Context context) {
149. super(context);
150. } //Android开发网提示关键部分在这里 @Override
151. public void addView(View child, int index, http://www.doczj.com/doc/ca10c5fc6037ee06eff9aef8941ea76e58fa4a08.htmlyoutPar ams params) {
152. super.addView(child, index, params);
153. int childId = child.getId();
154. if (childId == CHRONOMETER_ID && child instanceof Chron ometer) {
155. mChronometer = (Chronometer) child;
156. mChronometer.setOnChronometerTickListener(this); 157. // Check if Chronometer should move with with ProgressBa r
158. mChronometerFollow = (params.width == http://www.doczj.com/doc/ca10c5fc6037ee06eff9aef8941ea76e58fa4a08.htmlyo utParams.WRAP_CONTENT);
159. mChronometerGravity = (mChronometer.getGravity() & Gr avity.HORIZONTAL_GRAVITY_MASK);
160. } else if (childId == PROGRESSBAR_ID && child instanceof ProgressBar) {
161. mProgressBar = (ProgressBar) child;
162. }
163. } @android.view.RemotableViewMethod
164. public void setDurationBase(long durationBase) {
165. mDurationBase = durationBase;
166. if (mProgressBar == null || mChronometer == null) {
167. throw new RuntimeException("Expecting child ProgressBar with id " +
168. "'android.R.id.progress' and Chronometer id 'android.
R.id.text1'");
169. }
170. // Update the ProgressBar maximum relative to Chronometer base
171. mDuration = (int) (durationBase - mChronometer.getBase()); 172. if (mDuration <= 0) {
173. mDuration = 1;
174. }
175. mProgressBar.setMax(mDuration);
176. }
177. public void onChronometerTick(Chronometer chronometer) { 178. if (mProgressBar == null) {
179. throw new RuntimeException(
180. "Expecting child ProgressBar with id 'android.R.id.progre ss'");
181. }
182. // Stop Chronometer if we're past duration
183. long now = SystemClock.elapsedRealtime();
184. if (now >= mDurationBase) {
185. mChronometer.stop();
186. } int remaining = (int) (mDurationBase - now);
187. mProgressBar.setProgress(mDuration - remaining);
188. if (mChronometerFollow) {
189. http://www.doczj.com/doc/ca10c5fc6037ee06eff9aef8941ea76e58fa4a08.htmlyoutParams params;
190. params = (http://www.doczj.com/doc/ca10c5fc6037ee06eff9aef8941ea76e58fa4a08.htmlyoutParams) mProgressBar.g etLayoutParams();
191. int contentWidth = mProgressBar.getWidth() - (params.left Margin + params.rightMargin);
192. int leadingEdge = ((contentWidth * mProgressBar.getProgr ess()) /
193. mProgressBar.getMax()) + params.leftMargin; 194. int adjustLeft = 0;
195. int textWidth = mChronometer.getWidth();
196. if (mChronometerGravity == Gravity.RIGHT) {
197. adjustLeft = -textWidth;
198. } else if (mChronometerGravity == Gravity.CENTER_HORI ZONTAL) {
199. adjustLeft = -(textWidth / 2);
200. }
201. leadingEdge += adjustLeft;
202. int rightLimit = contentWidth - params.rightMargin - textWid th;
203. if (leadingEdge < params.leftMargin) {
204. leadingEdge = params.leftMargin;
205. } else if (leadingEdge > rightLimit) {
206. leadingEdge = rightLimit;
207. }
208. params = (http://www.doczj.com/doc/ca10c5fc6037ee06eff9aef8941ea76e58fa4a08.htmlyoutParams) mChronometer.
getLayoutParams();
209. params.leftMargin = leadingEdge;
210. mChronometer.requestLayout();
211. }
212. }
213. }
214.
