Android-several methods for updating the UI by threads

Android-several methods for updating the UI by threads

To update the UI, a new thread on Android needs to jump to the main thread to perform operations. The following are some solutions provided by foreigners. <喎?http: www.bkjia.com kf ware vc " target="_blank" class="keylink"> VcD4KPHA + PGJyPgo8L3A + CjxwPjHNqLn9VUm/2Lz + placement = "brush: java;"> private void loadIcon () {new Thread (new Runnable () {@ Overridepublic void run () {try {Thread. sleep (mDelay);} catch (InterruptedException e) {e. printStackTrace ();} mBitmap = BitmapFactory. decodeResource (getResources (), R. drawable. painter); mImageView. post (new Runnable () {@ Overridepublic void run () {mImageView. setImageBitmap (mBitmap );}});}}). start ();}
2. Call the main thread runOnUiThread to execute the modification.

new Thread(new Runnable() {@Overridepublic void run() {try {Thread.sleep(mDelay);} catch (InterruptedException e) {e.printStackTrace();}mBitmap = BitmapFactory.decodeResource(getResources(),R.drawable.painter);SimpleThreadingExample.this.runOnUiThread(new Runnable() {@Overridepublic void run() {mImageView.setImageBitmap(mBitmap);}});}}).start();

3. Use Handler to continuously post a runnable on another thread to execute the modification:

private class LoadIconTask implements Runnable {int resId;LoadIconTask(int resId) {this.resId = resId;}public void run() {handler.post(new Runnable() {@Overridepublic void run() {mProgressBar.setVisibility(ProgressBar.VISIBLE);}});mBitmap = BitmapFactory.decodeResource(getResources(), resId);// Simulating long-running operationfor (int i = 1; i < 11; i++) {sleep();final int step = i;handler.post(new Runnable() {@Overridepublic void run() {mProgressBar.setProgress(step * 10);}});}handler.post(new Runnable() {@Overridepublic void run() {mImageView.setImageBitmap(mBitmap);}});handler.post(new Runnable() {@Overridepublic void run() {mProgressBar.setVisibility(ProgressBar.INVISIBLE);}});}}

4. the following example uses Handlemessage to perform operations. It is interesting to use soft references. (Refer to the weak keyword in IOS). When handler sends a message, the obtainMessage adopts the pool recycle mechanism.

static class UIHandler extends Handler {WeakReference
 
   mParent;public UIHandler(WeakReference
  
    parent) {mParent = parent;}@Overridepublic void handleMessage(Message msg) {HandlerMessagesActivity parent = mParent.get();if (null != parent) {switch (msg.what) {case SET_PROGRESS_BAR_VISIBILITY: {parent.getProgressBar().setVisibility((Integer) msg.obj);break;}case PROGRESS_UPDATE: {parent.getProgressBar().setProgress((Integer) msg.obj);break;}case SET_BITMAP: {parent.getImageView().setImageBitmap((Bitmap) msg.obj);break;}}}}}Handler handler = new UIHandler(new WeakReference
   
    (this));private class LoadIconTask implements Runnable {private final int resId;private final Handler handler;LoadIconTask(int resId, Handler handler) {this.resId = resId;this.handler = handler;}public void run() {Message msg = handler.obtainMessage(SET_PROGRESS_BAR_VISIBILITY,ProgressBar.VISIBLE);handler.sendMessage(msg);final Bitmap tmp = BitmapFactory.decodeResource(getResources(),resId);for (int i = 1; i < 11; i++) {sleep();msg = handler.obtainMessage(PROGRESS_UPDATE, i * 10);handler.sendMessage(msg);}msg = handler.obtainMessage(SET_BITMAP, tmp);handler.sendMessage(msg);msg = handler.obtainMessage(SET_PROGRESS_BAR_VISIBILITY,ProgressBar.INVISIBLE);handler.sendMessage(msg);}private void sleep() {try {Thread.sleep(mDelay);} catch (InterruptedException e) {e.printStackTrace();}}}
   
  
 

5. AyncTask is also a common method.

class LoadIconTask extends AsyncTask
 
   {@Overrideprotected void onPreExecute() {mProgressBar.setVisibility(ProgressBar.VISIBLE);}@Overrideprotected Bitmap doInBackground(Integer... resId) {Bitmap tmp = BitmapFactory.decodeResource(getResources(), resId[0]);// simulating long-running operation for (int i = 1; i < 11; i++) {sleep();publishProgress(i * 10);}return tmp;}@Overrideprotected void onProgressUpdate(Integer... values) {mProgressBar.setProgress(values[0]);}@Overrideprotected void onPostExecute(Bitmap result) {mProgressBar.setVisibility(ProgressBar.INVISIBLE);mImageView.setImageBitmap(result);}private void sleep() {try {Thread.sleep(mDelay);} catch (InterruptedException e) {Log.e(TAG, e.toString());}}}
 

In any case, I just want to express that foreigners are sometimes quite interesting.