ProgressBar进度条.doc

ProgressBar进度条 extends View java.lang.Object ? android.view.View ? android.widget.ProgressBar Known Direct Subclasses AbsSeekBar, ContentLoadingProgressBar Known Indirect Subclasses AppCompatRatingBar, RatingBar, SeekBar Class Overview Visual indicator of progress in some operation. Displays a bar to the user representing how far the operation has progressed; the application can change the amount of progress (modifying the length of the bar) as it moves forward. There is also a secondary progress displayable on a progress bar which is useful for displaying intermediate progress, such as the buffer level during a streaming playback progress bar. A progress bar can also be made indeterminate. In indeterminate mode, the progress bar shows a cyclic animation without an indication of progress. This mode is used by applications when the length of the task is unknown. The indeterminate progress bar can be either a spinning wheel or a horizontal bar. The following code example shows how a progress bar can be used from a worker thread to update the user interface to notify the user of progress: public class MyActivity extends Activity { private static final int PROGRESS = 0x1; private ProgressBar mProgress; private int mProgressStatus = 0; private Handler mHandler = new Handler(); protected void onCreate(Bundle icicle) { super.onCreate(icicle); setContentView(R.gressbar_activity); mProgress = (ProgressBar) findViewById(R.gress_bar); // Start lengthy operation in a background thread new Thread(new Runnable() { public void run() { while (mProgressStatus 100) { mProgressStatus = doWork(); // Update the progress bar mHandler.post(new Runnable() { public void run() { mProgress.setProgress(mProgressStatus); } });