React Native: Android App stürzt ab, onNewIntent

Question

Das folgende Code-Snippet ist NFC-Modul für react-native. Ich habe damit NFC-Tag-IDs gelesen. Das Problem ist, wenn Sie die App in den Hintergrund stellen, wenn Sie erneut auf das App-Symbol klicken, wird die App abstürzen, aber wenn Sie es aus Aufgabenliste öffnen, funktioniert es gut.

NFC Lesemodul:

//package com.toastexample; 
 
package net.opencampus.android.client; 
 
import android.widget.Toast; 
 
import android.util.Log; 
 

 
import com.facebook.react.bridge.NativeModule; 
 
import com.facebook.react.bridge.ReactApplicationContext; 
 
import com.facebook.react.bridge.ReactContext; 
 
import com.facebook.react.bridge.ReactContextBaseJavaModule; 
 
import com.facebook.react.bridge.ReactMethod; 
 
import com.facebook.react.bridge.ActivityEventListener; 
 
import com.facebook.react.bridge.LifecycleEventListener; 
 

 
import android.app.Activity; 
 
import android.content.Intent; 
 
import android.nfc.NfcAdapter; 
 
import android.nfc.Tag; 
 
import java.nio.ByteBuffer; 
 
import com.facebook.react.bridge.WritableMap; 
 
import com.facebook.react.bridge.Arguments; 
 
import com.facebook.react.bridge.Promise; 
 
import com.facebook.react.modules.core.DeviceEventManagerModule; 
 
import android.support.annotation.Nullable; 
 

 
import java.util.Map; 
 
import java.util.HashMap; 
 

 
public class NfcReadModule extends ReactContextBaseJavaModule implements ActivityEventListener, LifecycleEventListener { 
 
public static final String TAG = "NFCActivity"; 
 
    private static final String DURATION_SHORT_KEY = "SHORT"; 
 
    private static final String DURATION_LONG_KEY = "LONG"; 
 

 
    private ReactApplicationContext reactContext; 
 

 
    private static final char[] HAX_ARRAY = "ABCDEF".toCharArray(); 
 
    String serialNumber; 
 
    String intentText = "Empty"; 
 
    Promise tagPromise; 
 

 
    public NfcReadModule(ReactApplicationContext reactContext) { 
 
    super(reactContext); 
 
    this.reactContext = reactContext; 
 
    this.reactContext.addActivityEventListener(this); 
 
    } 
 

 
    @Override 
 
    public String getName() { 
 
    return "NfcReadModule"; 
 
    } 
 

 
    @Override 
 
    public void onNewIntent(Intent intent) { 
 
    intentText = "onNewIntent"; 
 
    Tag tag = intent.getParcelableExtra(NfcAdapter.EXTRA_TAG); 
 
    serialNumber = bytesToHex(tag.getId()); 
 
    WritableMap params = Arguments.createMap(); 
 
    params.putString("serial", serialNumber); 
 
    sendEvent(this.reactContext, "tagDetected", params); 
 

 
    } 
 

 
    @ReactMethod 
 
    public void getCardId(Promise promise) { 
 
    this.tagPromise = promise; 
 
    } 
 

 
    @Override 
 
    public void onHostResume() { 
 
    
 
    } 
 

 
    @Override 
 
    public void onHostPause() { 
 
    
 
    } 
 

 
    @Override 
 
    public void onHostDestroy() { 
 
    
 
    } 
 

 
    @Override 
 
    public void onActivityResult(
 
     final Activity activity, 
 
     final int requestCode, 
 
     final int resultCode, 
 
     final Intent intent) { 
 

 
    } 
 

 
    @ReactMethod 
 
    public void show() { 
 

 
    } 
 

 
    @Override 
 
    public Map<String, Object> getConstants() { 
 
    final Map<String, Object> constants = new HashMap<>(); 
 
    constants.put(DURATION_SHORT_KEY, Toast.LENGTH_SHORT); 
 
    constants.put(DURATION_LONG_KEY, Toast.LENGTH_LONG); 
 
    return constants; 
 
    } 
 

 
    private static String bytesToHex(byte[] bytes) { 
 
    char[] hexChars = new char[bytes.length * 2]; 
 
    for (int j = 0; j < bytes.length; j++) { 
 
     int v = bytes[bytes.length - j - 1] & 0xFF; 
 
     hexChars[j * 2] = HAX_ARRAY[v >>> 4]; 
 
     hexChars[j * 2 + 1] = HAX_ARRAY[v & 0x0F]; 
 
    } 
 
    return new String(hexChars); 
 
    } 
 

 
    private void sendEvent(ReactContext reactContext, String eventName, @Nullable WritableMap params) { 
 
    if (reactContext.hasActiveCatalystInstance()) { 
 
     reactContext 
 
     .getJSModule(DeviceEventManagerModule.RCTDeviceEventEmitter.class) 
 
     .emit(eventName, params); 
 
    } 
 
    } 
 
}

Logs von logcat während Absturz:

05-09 10:34:03.457 22282 22282 E AndroidRuntime: FATAL EXCEPTION: main 
 
05-09 10:34:03.457 22282 22282 E AndroidRuntime: Process: net.xxxx.android.client, PID: 22282 
 
05-09 10:34:03.457 22282 22282 E AndroidRuntime: java.lang.NullPointerException: Attempt to invoke virtual method 'byte[] android.nfc.Tag.getId()' on a null object reference 
 
05-09 10:34:03.457 22282 22282 E AndroidRuntime: \t at net.xxxx.android.client.NfcReadModule.onNewIntent(NfcReadModule.java:61) 
 
05-09 10:34:03.457 22282 22282 E AndroidRuntime: \t at com.facebook.react.bridge.ReactContext.onNewIntent(ReactContext.java:208) 
 
05-09 10:34:03.457 22282 22282 E AndroidRuntime: \t at com.facebook.react.ReactInstanceManager.onNewIntent(ReactInstanceManager.java:503) 
 
05-09 10:34:03.457 22282 22282 E AndroidRuntime: \t at com.facebook.react.ReactActivityDelegate.onNewIntent(ReactActivityDelegate.java:189) 
 
05-09 10:34:03.457 22282 22282 E AndroidRuntime: \t at com.facebook.react.ReactActivity.onNewIntent(ReactActivity.java:99) 
 
05-09 10:34:03.457 22282 22282 E AndroidRuntime: \t at android.app.Instrumentation.callActivityOnNewIntent(Instrumentation.java:1223) 
 
05-09 10:34:03.457 22282 22282 E AndroidRuntime: \t at android.app.Instrumentation.callActivityOnNewIntent(Instrumentation.java:1235) 
 
05-09 10:34:03.457 22282 22282 E AndroidRuntime: \t at android.app.ActivityThread.deliverNewIntents(ActivityThread.java:2802) 
 
05-09 10:34:03.457 22282 22282 E AndroidRuntime: \t at android.app.ActivityThread.performNewIntents(ActivityThread.java:2817) 
 
05-09 10:34:03.457 22282 22282 E AndroidRuntime: \t at android.app.ActivityThread.handleNewIntent(ActivityThread.java:2833) 
 
05-09 10:34:03.457 22282 22282 E AndroidRuntime: \t at android.app.ActivityThread.-wrap15(ActivityThread.java) 
 
05-09 10:34:03.457 22282 22282 E AndroidRuntime: \t at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1556) 
 
05-09 10:34:03.457 22282 22282 E AndroidRuntime: \t at android.os.Handler.dispatchMessage(Handler.java:102) 
 
05-09 10:34:03.457 22282 22282 E AndroidRuntime: \t at android.os.Looper.loop(Looper.java:154) 
 
05-09 10:34:03.457 22282 22282 E AndroidRuntime: \t at android.app.ActivityThread.main(ActivityThread.java:6119) 
 
05-09 10:34:03.457 22282 22282 E AndroidRuntime: \t at java.lang.reflect.Method.invoke(Native Method) 
 
05-09 10:34:03.457 22282 22282 E AndroidRuntime: \t at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886) 
 
05-09 10:34:03.457 22282 22282 E AndroidRuntime: \t at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776) 
 
05-09 10:34:03.467 607 2381 W ActivityManager: Force finishing activity net.xxxx.android.client/.MainActivity

Was mache ich falsch? Danke im Voraus.

Answer 1

Fest durch einen Scheck hinzufügen, wenn der Tag nicht null ist:

@Override 
 
    public void onNewIntent(Intent intent) { 
 
    intentText = "onNewIntent"; 
 
    Tag tag = intent.getParcelableExtra(NfcAdapter.EXTRA_TAG); 
 
    if (tag != null) { 
 
     serialNumber = bytesToHex(tag.getId()); 
 
     WritableMap params = Arguments.createMap(); 
 
     params.putString("serial", serialNumber); 
 
     sendEvent(this.reactContext, "tagDetected", params); 
 
    } 
 
    }