我正在开发一个应用程序，用户输入他/她的声音，应用程序将计算其功能。所以我放置了一个进度对话框，通知用户应用程序正在计算其功能。首先，应用程序运行完美，然后在第三次运行时，进度对话框返回空指针异常。我不知道如何解决。这是logcat：
02-22 20:35:11.776: D/AndroidRuntime(24137): Shutting down VM
02-22 20:35:11.776: W/dalvikvm(24137): threadid=1: thread exiting with uncaught exception (group=0x4186bda0)
02-22 20:35:11.786: E/AndroidRuntime(24137): FATAL EXCEPTION: main
02-22 20:35:11.786: E/AndroidRuntime(24137): Process: com.neu.val.activity, PID: 24137
02-22 20:35:11.786: E/AndroidRuntime(24137): java.lang.NullPointerException
02-22 20:35:11.786: E/AndroidRuntime(24137): at android.app.ProgressDialog.setMessage(ProgressDialog.java:325)
02-22 20:35:11.786: E/AndroidRuntime(24137): at com.neu.val.activity.CreateVoiceSample$MfccTask.onProgressUpdate(CreateVoiceSample.java:341)
02-22 20:35:11.786: E/AndroidRuntime(24137): at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:648)
02-22 20:35:11.786: E/AndroidRuntime(24137): at android.os.Handler.dispatchMessage(Handler.java:102)
02-22 20:35:11.786: E/AndroidRuntime(24137): at android.os.Looper.loop(Looper.java:146)
02-22 20:35:11.786: E/AndroidRuntime(24137): at android.app.ActivityThread.main(ActivityThread.java:5653)
02-22 20:35:11.786: E/AndroidRuntime(24137): at java.lang.reflect.Method.invokeNative(Native Method)
02-22 20:35:11.786: E/AndroidRuntime(24137): at java.lang.reflect.Method.invoke(Method.java:515)
02-22 20:35:11.786: E/AndroidRuntime(24137): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1291)
02-22 20:35:11.786: E/AndroidRuntime(24137): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1107)
02-22 20:35:11.786: E/AndroidRuntime(24137): at dalvik.system.NativeStart.main(Native Method)
这是班级：
public class CreateVoiceSample extends ActionBarActivity {
private Button btSpeak, btCance, btSave;
private WaveRecorder waveRecorder;
private ProgressBar progressBar;
private TextView timerText;
private boolean stopped;
private int MAX_DURATION = 2500, progressTime, seconds;
private Timer timer;
static final String TAG = "VAP";
public String codebookString;
private long userId;
private Uri insertFeatures;
private AppDB appDB = new AppDB(this);
/** The recording output file. */
private static File outputFile = new File(
Environment
.getExternalStoragePublicDirectory(Environment.DIRECTORY_MUSIC),
"recording.wav");
@Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.recordvoice);
userId = getIntent().getLongExtra(Extras.EXTRA_USER_ID, 1);
initializeVar();
enableButtons(true, false, true);
}
public void initializeVar() {
btSpeak = (Button) findViewById(R.id.bSpeak);
btSave = (Button) findViewById(R.id.bSave);
btCancel = (Button) findViewById(R.id.bCancel);
progressBar = (ProgressBar) findViewById(R.id.progressBar1);
timerText = (TextView) findViewById(R.id.textView1);
stopped = true;
progressBar.setMax(MAX_DURATION);
startProgress();
}
public void actionBt(View v) {
if (v.getId() == R.id.bSpeak) {
startRecord();
} else if (v.getId() == R.id.bCancel) {
finish();
} else if (v.getId() == R.id.bSave) {
insertFeature(codebookString);
}
}
private void startRecord() {
// TODO Auto-generated method stub
enableButtons(false, false, false);
seconds = 1000;
progressTime = 0;
progressBar.setProgress(0);
timerText.setText("00:00:00");
if (outputFile.exists())
outputFile.delete();
waveRecorder = new WaveRecorder(8000);
waveRecorder.setOutputFile(outputFile.getAbsolutePath());
stopped = false;
try {
waveRecorder.prepare();
waveRecorder.start();
Toast.makeText(getApplicationContext(), "Recording started ... ",
Toast.LENGTH_SHORT).show();
} catch (Exception e) {
e.printStackTrace();
}
}
public void stopRecord() {
stopped = true;
waveRecorder.stop();
waveRecorder.release();
waveRecorder.reset();
timer.cancel();
Toast.makeText(getApplicationContext(), "Recording stopped..", Toast.LENGTH_SHORT).show();
calculateMfccs();
startProgress();
}
public void startProgress() {
enableButtons(true,true,true);
final Handler handler = new Handler();
TimerTask timerTask = new TimerTask() {
@Override
public void run() {
handler.post(new Runnable() {
@Override
public void run() {
try {
progress();
} catch (Exception e) {
// TODO Auto-generated catch block
}
}
});
}
};
timer = new Timer();
timer.schedule(timerTask, 1, 1000);
}
public void enableButtons(boolean startBt, boolean stopBt, boolean saveBt,
boolean cancelBt) {
btSpeak.setEnabled(startBt);
btSave.setEnabled(saveBt);
btCancel.setEnabled(cancelBt);
}
public void progress() {
if (!stopped) // call ui only when the progress is not stopped
{
if (progressTime < MAX_DURATION) {
runOnUiThread(new Runnable() {
@Override
public void run() {
try {
int secondsText = seconds / 1000;
progressTime = progressBar.getProgress() + 1000;
progressBar.setProgress(progressTime);
timerText.setText("00:00:0" + secondsText);
seconds += 1000;
} catch (Exception e) {
}
}
});
} else {
stopRecord();
}
}
}
private void calculateMfccs() {
new MfccTask(this).execute(outputFile.getAbsolutePath());
}
private void insertFeature(String password) {
enableButtons(true,false,true);
long modeId = ((VoiceApplication)getApplication()).getModeId();
ContentValues cv = new ContentValues();
cv.put(Feature.SUBJECT_ID, userId);
cv.put(Feature.MODE_ID, modeId);
cv.put(Feature.REPRESENTATION, password);
insertFeatures = this.getContentResolver().insert(Feature.CONTENT_URI, cv);
appDB.onClose();
finish();
Intent changePassIntent = new Intent(this,MainActivity.class);
changePassIntent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK|IntentCompat.FLAG_ACTIVITY_CLEAR_TASK);
this.startActivity(changePassIntent);
}
class MfccTask extends AsyncTask<String, Object, String> {
private ProgressDialog progressDialog;
private final Activity parentActivity;
public MfccTask(Activity parentActivity) {
this.parentActivity = parentActivity;
}
@Override
protected String doInBackground(String... params) {
String filename = params[0];
WavReader wavReader = new WavReader(filename);
Log.i(TAG, "Starting to read from file " + filename);
double[] samples = readSamples(wavReader);
Log.i(TAG, "Starting to calculate MFCC");
double[][] mfcc = calculateMfcc(samples);
FeatureVector pl = createFeatureVector(mfcc);
KMeans kmeans = doClustering(pl);
Codebook cb = createCodebook(kmeans);
Gson gson = new Gson();
String codebookJsonString = gson.toJson(cb, Codebook.class);
Log.i(TAG, codebookJsonString);
return codebookJsonString;
}
private Codebook createCodebook(KMeans kmeans) {
int numberClusters = kmeans.getNumberClusters();
Matrix[] centers = new Matrix[numberClusters];
for (int i = 0; i < numberClusters; i++) {
centers[i] = kmeans.getCluster(i).getCenter();
}
Codebook cb = new Codebook();
cb.setLength(numberClusters);
cb.setCentroids(centers);
return cb;
}
private KMeans doClustering(FeatureVector pl) {
long start;
KMeans kmeans = new KMeans(Constants.CLUSTER_COUNT, pl,
Constants.CLUSTER_MAX_ITERATIONS);
Log.i(TAG, "Prepared k means clustering");
start = System.currentTimeMillis();
progressDialog.setProgressStyle(ProgressDialog.STYLE_SPINNER);
kmeans.run();
Log.i(TAG,
"Clustering finished, total time = "
+ (System.currentTimeMillis() - start) + "ms");
return kmeans;
}
private FeatureVector createFeatureVector(double[][] mfcc) {
int vectorSize = mfcc[0].length;
int vectorCount = mfcc.length;
Log.i(TAG, "Creating pointlist with dimension=" + vectorSize
+ ", count=" + vectorCount);
FeatureVector pl = new FeatureVector(vectorSize, vectorCount);
for (int i = 0; i < vectorCount; i++) {
pl.add(mfcc[i]);
}
Log.d(TAG, "Added all MFCC vectors to pointlist");
return pl;
}
private short createSample(byte[] buffer) {
short sample = 0;
// hardcoded two bytes here
short b1 = buffer[0];
short b2 = buffer[1];
b2 <<= 8;
sample = (short) (b1 | b2);
return sample;
}
private double[][] calculateMfcc(double[] samples) {
MFCC mfccCalculator = new MFCC(Constants.SAMPLERATE,
Constants.WINDOWSIZE, Constants.COEFFICIENTS, false,
Constants.MINFREQ + 1, Constants.MAXFREQ, Constants.FILTERS);
int hopSize = Constants.WINDOWSIZE / 2;
int mfccCount = (samples.length / hopSize) - 1;
double[][] mfcc = new double[mfccCount][Constants.COEFFICIENTS];
long start = System.currentTimeMillis();
for (int i = 0, pos = 0; pos < samples.length - hopSize; i++, pos += hopSize) {
mfcc[i] = mfccCalculator.processWindow(samples, pos);
if (i % 20 == 0) {
publishProgress("Calculating features...", i, mfccCount);
}
}
publishProgress("Calculating features...", mfccCount, mfccCount);
Log.i(TAG, "Calculated " + mfcc.length + " vectors of MFCCs in "
+ (System.currentTimeMillis() - start) + "ms");
return mfcc;
}
private double[] readSamples(WavReader wavReader) {
int sampleSize = wavReader.getFrameSize();
int sampleCount = wavReader.getPayloadLength() / sampleSize;
int windowCount = (int) Math.floor(sampleCount
/ Constants.WINDOWSIZE);
byte[] buffer = new byte[sampleSize];
double[] samples = new double[windowCount * Constants.WINDOWSIZE];
try {
for (int i = 0; i < samples.length; i++) {
wavReader.read(buffer, 0, sampleSize);
samples[i] = createSample(buffer);
if (i % 1000 == 0) {
publishProgress("Reading samples...", i, samples.length);
}
}
} catch (IOException e) {
Log.e(TAG, "Exception in reading samples", e);
}
return samples;
}
@Override
protected void onPostExecute(String result) {
codebookString = result;
progressDialog.dismiss();
}
@Override
protected void onPreExecute() {
progressDialog = new ProgressDialog(parentActivity);
progressDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
progressDialog.setTitle("Working...");
progressDialog.setMessage("Working...");
progressDialog.setProgress(0);
progressDialog.setMax(10000);
progressDialog.show();
progressDialog.setCancelable(false);
progressDialog.setCanceledOnTouchOutside(false);
}
@Override
protected void onProgressUpdate(Object... values) {
String msg = (String) values[0];
Integer current = (Integer) values[1];
Integer max = (Integer) values[2];
progressDialog.setMessage(msg);
progressDialog.setProgress(current);
progressDialog.setMax(max);
}
}
}
，这是发生错误的行（341行）：
progressDialog.setMessage(msg);
答案 0 :(得分：0)
我认为问题出在actionBt，其中函数startRecord（）被调用，而行 progressBar.setProgress（0）; ，如果progressBar尚未初始化，则为will raise.its不是在不同的行中多次初始化全局变量的好方法。