我已经看到了与此问题相关的所有其他问题，但似乎没有任何帮助。我想要实现的只是非常非常简单。
我想在OnCreate（）方法中将不确定进度条的可见性更改为不可见。但我只是因为某种原因继续得到NullPointerException。是的，我使用正确的ID来引用进度条。
public class MainActivity extends Activity implements
RecognitionListener {
private static TextView txt;
ProgressBar pb;
/* Named searches allow to quickly reconfigure the decoder */
private static final String KWS_SEARCH = "wakeup";
/* Keyword we are looking for to activate menu */
private static final String KEYPHRASE = "hey iris";
/* Used to handle permission request */
private static final int PERMISSIONS_REQUEST_RECORD_AUDIO = 1;
private SpeechRecognizer recognizer;
private HashMap<String, Integer> captions;
@Override
public void onCreate(Bundle state) {
super.onCreate(state);
setContentView(R.layout.activity_main);
txt = (TextView) findViewById(R.id.result_text);
pb = (ProgressBar) findViewById(R.id.pbar);
pb.setVisibility(View.GONE);
System.out.println(pb.getVisibility());
captions = new HashMap<>();
captions.put(KWS_SEARCH, R.string.kws_caption);
setContentView(R.layout.activity_main);
((TextView) findViewById(R.id.caption_text))
.setText("Preparing the application");
// Check if user has given permission to record audio
int permissionCheck = ContextCompat.checkSelfPermission(getApplicationContext(), Manifest.permission.RECORD_AUDIO);
if (permissionCheck != PackageManager.PERMISSION_GRANTED) {
ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.RECORD_AUDIO}, PERMISSIONS_REQUEST_RECORD_AUDIO);
return;
}
// Recognizer initialization is a time-consuming and it involves IO,
// so we execute it in async task
new SetupTask(this).execute();
}
private static class SetupTask extends AsyncTask<Void, Integer, Exception> {
WeakReference<MainActivity> activityReference;
SetupTask(MainActivity activity) {
this.activityReference = new WeakReference<>(activity);
}
@Override
protected void onPreExecute() {
super.onPreExecute();
}
@Override
protected void onProgressUpdate(Integer... values) {
super.onProgressUpdate(values);
System.out.println(values[0]);
}
@Override
protected Exception doInBackground(Void... params) {
try {
Assets assets = new Assets(activityReference.get());
File assetDir = assets.syncAssets();
activityReference.get().setupRecognizer(assetDir);
} catch (IOException e) {
return e;
}
return null;
}
@Override
protected void onPostExecute(Exception result) {
if (result != null) {
((TextView) activityReference.get().findViewById(R.id.caption_text))
.setText("Failed to init recognizer " + result);
} else {
activityReference.get().switchSearch(KWS_SEARCH);
}
}
}
@Override
public void onRequestPermissionsResult(int requestCode,
@NonNull String[] permissions, @NonNull int[] grantResults) {
super.onRequestPermissionsResult(requestCode, permissions, grantResults);
if (requestCode == PERMISSIONS_REQUEST_RECORD_AUDIO) {
if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
// Recognizer initialization is a time-consuming and it involves IO,
// so we execute it in async task
new SetupTask(this).execute();
} else {
finish();
}
}
}
@Override
public void onDestroy() {
super.onDestroy();
if (recognizer != null) {
recognizer.cancel();
recognizer.shutdown();
}
}
/**
* In partial result we get quick updates about current hypothesis. In
* keyword spotting mode we can react here, in other modes we need to wait
* for final result in onResult.
*/
@Override
public void onPartialResult(Hypothesis hypothesis) {
if (hypothesis == null)
return;
String text = hypothesis.getHypstr();
if (text.equals(KEYPHRASE)) {
recognizer.stop();
Intent intent = new Intent(this, ListenActivity.class);
intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity ( intent );
recognizer.cancel();
recognizer.shutdown();
finish();
}
}
/**
* This callback is called when we stop the recognizer.
*/
@Override
public void onResult(Hypothesis hypothesis) {
((TextView) findViewById(R.id.result_text)).setText("");
if (hypothesis != null) {
}
}
@Override
public void onBeginningOfSpeech() {
}
/**
* We stop recognizer here to get a final result
*/
@Override
public void onEndOfSpeech() {
if (!recognizer.getSearchName().equals(KWS_SEARCH))
switchSearch(KWS_SEARCH);
}
private void switchSearch(String searchName) {
recognizer.stop();
// If we are not spotting, start listening with timeout (10000 ms or 10 seconds).
if (searchName.equals(KWS_SEARCH))
recognizer.startListening(searchName);
else
recognizer.startListening(searchName, 1000);
String caption = getResources().getString(captions.get(searchName));
((TextView) findViewById(R.id.caption_text)).setText(caption);
}
private void setupRecognizer(File assetsDir) throws IOException {
// The recognizer can be configured to perform multiple searches
// of different kind and switch between them
recognizer = SpeechRecognizerSetup.defaultSetup()
.setAcousticModel(new File(assetsDir, "en-us-ptm"))
.setDictionary(new File(assetsDir, "cmudict-en-us.dict"))
.getRecognizer();
recognizer.addListener(this);
/* In your application you might not need to add all those searches.
They are added here for demonstration. You can leave just one.
*/
// Create keyword-activation search.
recognizer.addKeyphraseSearch(KWS_SEARCH, KEYPHRASE);
}
@Override
public void onError(Exception error) {
((TextView) findViewById(R.id.caption_text)).setText(error.getMessage());
}
@Override
public void onTimeout() {
switchSearch(KWS_SEARCH);
}
}
activity_main
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<TextView
android:id="@+id/result_text"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textAppearance="?android:attr/textAppearanceMedium"
android:textColor="@android:color/darker_gray"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toEndOf="@+id/caption_text"
app:layout_constraintTop_toTopOf="parent" />
<TextView
android:id="@+id/caption_text"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_horizontal"
android:layout_marginBottom="481dp"
android:textAppearance="?android:attr/textAppearanceLarge"
android:typeface="sans"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<ProgressBar
android:id="@+id/pbar"
style="?android:attr/progressBarStyle"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
tools:layout_editor_absoluteX="167dp"
tools:layout_editor_absoluteY="258dp" />
</android.support.constraint.ConstraintLayout>
答案 0 :(得分：2)
您忘记在setContentView(R.layout.layoutWithProgressbar)
pb = (ProgressBar) findViewById(R.id.pbar);
public class MainActivity extends Activity implements
RecognitionListener {
ProgressBar pb;
@Override
public void onCreate(Bundle state) {
super.onCreate(state);
setContentView(R.layout.layoutWithProgressbar);
//^^^^^^^^^^^^^^^^^^^
// without this, there is no layout or view hierarchy
// attached with the MainActivity
// or probably setContentView(R.layout.main_activity);
pb = (ProgressBar) findViewById(R.id.pbar);
//pb.setVisibility(View.INVISIBLE);
pb.setVisibility(View.GONE);
}
}
另一个问题是，您正在将布局重新设置为同一个新状态
setContentView(R.layout.activity_main);
txt = (TextView) findViewById(R.id.result_text);
pb = (ProgressBar) findViewById(R.id.pbar);
pb.setVisibility(View.GONE);
System.out.println(pb.getVisibility());
captions = new HashMap<>();
captions.put(KWS_SEARCH, R.string.kws_caption);
//setContentView(R.layout.activity_main); remove this