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Ich arbeite an einem Barcode-Scanner-App, wo auf die Schaltfläche klicken Sie in der ersten Aktivität, ich bin auf dem Barcode Scanner Aktivität, wo ich Zxing-Bibliothek Funktionalitäten importieren. Sobald der Scan abgeschlossen ist, gehe ich zu einer dritten Aktivität, wo ich die gescannten Ergebnisse zeige. Beim Klicken auf eine Schaltfläche in der 3. Aktivität komme ich zurück zur ersten Aktivität. Bei Geräten mit Marshmallow läuft der Code einwandfrei. Aber das Problem tritt bei Geräten auf, die Versionen unterhalb von Marshmallow haben. Nach dem Zurückgehen zur ersten Aktivität von der dritten Aktivität, wenn ich die Taste erneut drücke, wird die Scanneraktivität angezeigt, aber die Kamera startet nicht. Es zeigt nur eine leere Seite. Bitte helfen Sie. Im Folgenden poste ich meine Codes für alle 3 Aktivitäten.Zxing Barcode-Scanner Problem in Android
First Activity:
public class FirstActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_first);
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
getWindow().addFlags(WindowManager.LayoutParams.FLAG_DRAWS_SYSTEM_BAR_BACKGROUNDS);
getWindow().setStatusBarColor(Color.parseColor("#FDB50A"));
}
ImageView Scan= (ImageView) findViewById(R.id.scanButton);
Scan.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
FirstActivity.this.finish();
Intent nextPage= new Intent(FirstActivity.this,MainActivity.class);
startActivity(nextPage);
}
});
ScannerActivity:
public class MainActivity extends AppCompatActivity implements ZXingScannerView.ResultHandler{
Integer response = 0 ;
int currentIndex=0;
Boolean flash=false;
DataBaseHelper dataBaseHelper;
private ZXingScannerView mScannerView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Log.e("onCreate", "onCreate");
checkPermissions();
mScannerView = new ZXingScannerView(this);
mScannerView.setResultHandler(this);
boolean cam= isCameraUsebyApp();
Log.d("cameraBar",cam+"");
if(cam)
{
mScannerView.stopCamera();
}
cam= isCameraUsebyApp();
Log.d("cameraBar",cam+"");
mScannerView.startCamera();
// FrameLayout frameLayout= new FrameLayout(this);
// FrameLayout.LayoutParams mainParam= new FrameLayout.LayoutParams(LayoutParams.MATCH_PARENT,LayoutParams.MATCH_PARENT);
// frameLayout.setLayoutParams(mainParam);
// Button scanButton= new Button(this);
dataBaseHelper= new DataBaseHelper(this);
if(dataBaseHelper.checkDataBase()==false)
{
try {
dataBaseHelper.createDataBase();
} catch (IOException e)
{
e.printStackTrace();
}
}
else{
}
Log.d("AnimeshSQL","copy");
dataBaseHelper.openDataBase();
// List<String> data=dataBaseHelper.getQuotes("n",1);
// Log.d("AnimeshSQL",data.get(0).toString());
LayoutParams params =
new LinearLayout.LayoutParams(
LayoutParams.WRAP_CONTENT,
LayoutParams.WRAP_CONTENT);
// scanButton.setBackground(getResources().getDrawable(R.drawable.round_button));
// scanButton.setText("Flash");
// scanButton.setOnClickListener(new View.OnClickListener() {
// @Override
// public void onClick(View v) {
// if(flash==false)
// {
// flash=true;
//
//
// }
// else
// {
// flash=false;
// }
// mScannerView.setFlash(flash);
// }
// });
// scanButton.setLayoutParams(params);
// frameLayout.addView(mScannerView);
// frameLayout.addView(scanButton);
// setContentView(mScannerView);
checkPermissions();
if(response == 1) {
mScannerView = null;
mScannerView = new ZXingScannerView(this);
setContentView(mScannerView);
response = 0;
}
}
public boolean isCameraUsebyApp() {
Camera camera = null;
try {
camera = Camera.open();
} catch (RuntimeException e) {
return true;
} finally {
if (camera != null) camera.release();
}
return false;
}
private void checkPermissions() {
try {
for (int i = currentIndex; i < permissions.length; i++) {
currentIndex = currentIndex + 1;
int result = ContextCompat.checkSelfPermission(context, permissions[i]);
if (result == PackageManager.PERMISSION_GRANTED) {
} else {
requestPermission(permissions[i]);
return;
}
}
} catch (Exception e) {
e.printStackTrace();
}
}
Activity activity = this;
Context context = this;
String[] permissions = new String[]{Manifest.permission.CAMERA, Manifest.permission.WRITE_EXTERNAL_STORAGE};
private void requestPermission(String permission) {
//
ActivityCompat.requestPermissions(activity, new String[]{permission}, 101);
//
}
@Override
public void onRequestPermissionsResult(int requestCode, String permissions[], int[] grantResults) {
switch (requestCode) {
case 101:
if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
//
checkPermissions();
} else {
try {
// FuncUtils.showToast(context, permissions[0] + " Denied!!!");
} catch (Exception e) {
e.printStackTrace();
}
//
///
}
break;
}
}
@Override
public void onResume() {
super.onResume();
if(response == 1) {
mScannerView = null;
mScannerView = new ZXingScannerView(this);
setContentView(mScannerView);
response = 0;
}
mScannerView.setResultHandler(this);
mScannerView.startCamera();
}
@Override
public void onDestroy() {
super.onDestroy();
mScannerView.stopCamera();
}
@Override
protected void onRestart() {
super.onRestart();
Log.d("ani","onrestart");
}
@Override
public void handleResult(Result rawResult)
{
//Some codes to handle the result
Intent intent= new Intent(this,ScanResultActivity.class);
startActivity(intent);
//vbn
mScannerView.stopCamera();
MainActivity.this.finish();
}
}
Final Activity:
public class ScanResultActivity extends AppCompatActivity {
SharedPreferences prefs;
Button ok;
ImageView Hubbell,CI;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_scan_result);
prefs = getSharedPreferences("ScanPref", MODE_PRIVATE);
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
getWindow().addFlags(WindowManager.LayoutParams.FLAG_DRAWS_SYSTEM_BAR_BACKGROUNDS);
getWindow().setStatusBarColor(Color.parseColor("#FDB50A"));
}
//Codes to show the data
ok.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
ScanResultActivity.this.finish();
Intent nextPage= new Intent(ScanResultActivity.this,FirstActivity.class);
startActivity(nextPage);
}
});