安卓：空指针异常 [英] Android: NullPointer Exception
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问题描述
这是我在LogCat中得到错误。
This is the error that I get in Logcat.
04-23 08:00:07.524: E/AndroidRuntime(1384): FATAL EXCEPTION: main
04-23 08:00:07.524: E/AndroidRuntime(1384): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.datumdroid.android.ocr.simple/com.datumdroid.android.ocr.simple.SimpleAndroidOCRActivity}: java.lang.NullPointerException
04-23 08:00:07.524: E/AndroidRuntime(1384): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180)
04-23 08:00:07.524: E/AndroidRuntime(1384): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
04-23 08:00:07.524: E/AndroidRuntime(1384): at android.app.ActivityThread.access$600(ActivityThread.java:141)
04-23 08:00:07.524: E/AndroidRuntime(1384): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
04-23 08:00:07.524: E/AndroidRuntime(1384): at android.os.Handler.dispatchMessage(Handler.java:99)
04-23 08:00:07.524: E/AndroidRuntime(1384): at android.os.Looper.loop(Looper.java:137)
04-23 08:00:07.524: E/AndroidRuntime(1384): at android.app.ActivityThread.main(ActivityThread.java:5039)
04-23 08:00:07.524: E/AndroidRuntime(1384): at java.lang.reflect.Method.invokeNative(Native Method)
04-23 08:00:07.524: E/AndroidRuntime(1384): at java.lang.reflect.Method.invoke(Method.java:511)
04-23 08:00:07.524: E/AndroidRuntime(1384): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
04-23 08:00:07.524: E/AndroidRuntime(1384): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
04-23 08:00:07.524: E/AndroidRuntime(1384): at dalvik.system.NativeStart.main(Native Method)
04-23 08:00:07.524: E/AndroidRuntime(1384): Caused by: java.lang.NullPointerException
04-23 08:00:07.524: E/AndroidRuntime(1384): at com.datumdroid.android.ocr.simple.SimpleAndroidOCRActivity.onCreate(SimpleAndroidOCRActivity.java:68)
04-23 08:00:07.524: E/AndroidRuntime(1384): at android.app.Activity.performCreate(Activity.java:5104)
04-23 08:00:07.524: E/AndroidRuntime(1384): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)
04-23 08:00:07.524: E/AndroidRuntime(1384): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144)
开机画面活动
public class SplashAct extends Activity {
/** Called when the activity is first created. */
private final Handler mHandler = new Handler();
private static final int duration = 1500;
@Override
protected void onCreate(final Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_NO_TITLE);
setContentView(R.layout.splash);
mHandler.postDelayed(mPendingLauncherRunnable,
SplashAct.duration);
}
@Override
protected void onPause() {
super.onPause();
mHandler.removeCallbacks(mPendingLauncherRunnable);
}
private final Runnable mPendingLauncherRunnable = new Runnable() {
public void run() {
final Intent intent = new Intent(SplashAct.this,
SimpleAndroidOCRActivity.class);
startActivity(intent);
finish();
}
};
}
主要活动
public class SimpleAndroidOCRActivity extends Activity implements OnInitListener {
public static final String PACKAGE_NAME = "com.datumdroid.android.ocr.simple";
public static final String DATA_PATH = Environment
.getExternalStorageDirectory().toString() + "/SimpleAndroidOCR/";
// You should have the trained data file in assets folder
// You can get them at:
// http://code.google.com/p/tesseract-ocr/downloads/list
public static final String lang = "eng";
private static final String TAG = "SimpleAndroidOCR.java";
protected Button _button, btnSpeak;
// protected ImageView _image;
protected EditText _field;
protected String _path;
protected boolean _taken;
protected static final String PHOTO_TAKEN = "photo_taken";
//tts
private TextToSpeech tts;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
//tts
tts = new TextToSpeech(this, this);
btnSpeak = (Button) findViewById(R.id.button1);
btnSpeak.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View arg0) {
speakOut();
}
});
//ocr
String[] paths = new String[] { DATA_PATH, DATA_PATH + "tessdata/" };
for (String path : paths) {
File dir = new File(path);
if (!dir.exists()) {
if (!dir.mkdirs()) {
Log.v(TAG, "ERROR: Creation of directory " + path + " on sdcard failed");
return;
} else {
Log.v(TAG, "Created directory " + path + " on sdcard");
}
}
}
// lang.traineddata file with the app (in assets folder)
// You can get them at:
// http://code.google.com/p/tesseract-ocr/downloads/list
// This area needs work and optimization
if (!(new File(DATA_PATH + "tessdata/" + lang + ".traineddata")).exists()) {
try {
AssetManager assetManager = getAssets();
InputStream in = assetManager.open("tessdata/eng.traineddata");
//GZIPInputStream gin = new GZIPInputStream(in);
OutputStream out = new FileOutputStream(DATA_PATH
+ "tessdata/eng.traineddata");
// Transfer bytes from in to out
byte[] buf = new byte[1024];
int len;
//while ((lenf = gin.read(buff)) > 0) {
while ((len = in.read(buf)) > 0) {
out.write(buf, 0, len);
}
in.close();
//gin.close();
out.close();
Log.v(TAG, "Copied " + lang + " traineddata");
} catch (IOException e) {
Log.e(TAG, "Was unable to copy " + lang + " traineddata " + e.toString());
}
}
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
// _image = (ImageView) findViewById(R.id.image);
_field = (EditText) findViewById(R.id.field);
_button = (Button) findViewById(R.id.button);
_button.setOnClickListener(new ButtonClickHandler());
_path = DATA_PATH + "/ocr.jpg";
}
public class ButtonClickHandler implements View.OnClickListener {
public void onClick(View view) {
Log.v(TAG, "Starting Camera app");
startCameraActivity();
}
}
// Simple android photo capture:
// http://labs.makemachine.net/2010/03/simple-android-photo-capture/
protected void startCameraActivity() {
File file = new File(_path);
Uri outputFileUri = Uri.fromFile(file);
final Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
intent.putExtra(MediaStore.EXTRA_OUTPUT, outputFileUri);
startActivityForResult(intent, 0);
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
Log.i(TAG, "resultCode: " + resultCode);
if (resultCode == -1) {
onPhotoTaken();
} else {
Log.v(TAG, "User cancelled");
}
}
@Override
protected void onSaveInstanceState(Bundle outState) {
outState.putBoolean(SimpleAndroidOCRActivity.PHOTO_TAKEN, _taken);
}
@Override
protected void onRestoreInstanceState(Bundle savedInstanceState) {
Log.i(TAG, "onRestoreInstanceState()");
if (savedInstanceState.getBoolean(SimpleAndroidOCRActivity.PHOTO_TAKEN)) {
onPhotoTaken();
}
}
protected void onPhotoTaken() {
_taken = true;
BitmapFactory.Options options = new BitmapFactory.Options();
options.inSampleSize = 4;
Bitmap bitmap = BitmapFactory.decodeFile(_path, options);
try {
ExifInterface exif = new ExifInterface(_path);
int exifOrientation = exif.getAttributeInt(
ExifInterface.TAG_ORIENTATION,
ExifInterface.ORIENTATION_NORMAL);
Log.v(TAG, "Orient: " + exifOrientation);
int rotate = 0;
switch (exifOrientation) {
case ExifInterface.ORIENTATION_ROTATE_90:
rotate = 90;
break;
case ExifInterface.ORIENTATION_ROTATE_180:
rotate = 180;
break;
case ExifInterface.ORIENTATION_ROTATE_270:
rotate = 270;
break;
}
Log.v(TAG, "Rotation: " + rotate);
if (rotate != 0) {
// Getting width & height of the given image.
int w = bitmap.getWidth();
int h = bitmap.getHeight();
// Setting pre rotate
Matrix mtx = new Matrix();
mtx.preRotate(rotate);
// Rotating Bitmap
bitmap = Bitmap.createBitmap(bitmap, 0, 0, w, h, mtx, false);
}
// Convert to ARGB_8888, required by tess
bitmap = bitmap.copy(Bitmap.Config.ARGB_8888, true);
} catch (IOException e) {
Log.e(TAG, "Couldn't correct orientation: " + e.toString());
}
// _image.setImageBitmap( bitmap );
Log.v(TAG, "Before baseApi");
TessBaseAPI baseApi = new TessBaseAPI();
baseApi.setDebug(true);
baseApi.init(DATA_PATH, lang);
baseApi.setImage(bitmap);
String recognizedText = baseApi.getUTF8Text();
baseApi.end();
// You now have the text in recognizedText var, you can do anything with it.
// We will display a stripped out trimmed alpha-numeric version of it (if lang is eng)
// so that garbage doesn't make it to the display.
Log.v(TAG, "OCRED TEXT: " + recognizedText);
if ( lang.equalsIgnoreCase("eng") ) {
recognizedText = recognizedText.replaceAll("[^a-zA-Z0-9]+", " ");
}
recognizedText = recognizedText.trim();
if ( recognizedText.length() != 0 ) {
_field.setText(_field.getText().toString().length() == 0 ? recognizedText : _field.getText() + " " + recognizedText);
_field.setSelection(_field.getText().toString().length());
}
// Cycle done.
}
//tts
@Override
public void onDestroy() {
// Don't forget to shutdown tts!
if (tts != null) {
tts.stop();
tts.shutdown();
}
super.onDestroy();
}
@Override
public void onInit(int status) {
if (status == TextToSpeech.SUCCESS) {
int result = tts.setLanguage(Locale.US);
if (result == TextToSpeech.LANG_MISSING_DATA
|| result == TextToSpeech.LANG_NOT_SUPPORTED) {
Log.e("TTS", "This Language is not supported");
} else {
btnSpeak.setEnabled(true);
speakOut();
}
} else {
Log.e("TTS", "Initilization Failed!");
}
}
private void speakOut() {
String text = _field.getText().toString();
tts.speak(text, TextToSpeech.QUEUE_FLUSH, null);
}
}
这是我的类文件，在技术上，该文件的OCR部分是从样品code，我要去哪里错了？我让过去的闪屏的活动没有任何问题。我得到空指针例外，如果我赞扬btnSpeak线View.OnClickListener，我得到superOnCreate错误，增加super.onCreate也没有帮助。
This is my class file, technically, the OCR part of the file is from a sample code, where am I going wrong? I get past the splash screen activity without any problem. I get NullPointer exception, if I commend the btnSpeak lines for View.OnClickListener, I get superOnCreate error, adding super.onCreate doesn't help either.
我无能。
顺便说一句，按钮，按钮1和场均钮，分别与一个EditText的ID。
btw, button, button1 and field are id of Button, Button and an EditText respectively.
推荐答案
尤尔都缺少一套关于的onCreate 布局 SimpleAndroidOCRActivity
Yor are missing to set layout on onCreate of SimpleAndroidOCRActivity
为异常说：对 SimpleAndroidOCRActivity.onCreate（SimpleAndroidOCRActivity.java:68）
所以做到这一点。
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
//tts//<<<<<-----------set a layout here first like setContentView(R.layout.main);
tts = new TextToSpeech(this, this);
btnSpeak = (Button) findViewById(R.id.button1); //then get button or text id
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