Merge pull request #578 from AltBeacon/fix-cme-on-start-passive-scan

Fix ConcurrentModificationException starting passive scan on Android 8

CHANGELOG.md

@@ -1,9 +1,13 @@
 ### Development
 
 Bug Fixes:
+ - Fix ConcurrentModificationException crashing app on Android 8 when monitored regions are
+   changed at the same time the app shifts from active scanning to passive scanning. 
+   (#578, David G. Young)
  - Fix ConcurrentModifictionExceptions starting ScanJobs.  (#584, #588, David G. Young)
  - Fix NullPointerException when BluetoothLeScanner cannot be obtained.
    (#583, David G. Young)
+
 ### 2.12.2 / 2017-08-31
 
 [Full Changelog](https://github.com/AltBeacon/android-beacon-library/compare/2.12.1...2.12.2)

src/main/java/org/altbeacon/beacon/service/ScanJob.java

@@ -17,6 +17,8 @@
 import org.altbeacon.beacon.distance.ModelSpecificDistanceCalculator;
 import org.altbeacon.beacon.logging.LogManager;
 import org.altbeacon.beacon.utils.ProcessUtils;
+
+import java.util.ArrayList;
 import java.util.List;
 
 
@@ -103,7 +105,9 @@ public void run() {
     private void startPassiveScanIfNeeded() {
         LogManager.d(TAG, "Checking to see if we need to start a passive scan");
         boolean insideAnyRegion = false;
-        for (Region region : mScanState.getMonitoringStatus().regions()) {
+        // Clone the collection before iterating to prevent ConcurrentModificationException per #577
+        List<Region> regions = new ArrayList<>(mScanState.getMonitoringStatus().regions());
+        for (Region region : regions) {
             RegionMonitoringState state = mScanState.getMonitoringStatus().stateOf(region);
             if (state != null && state.getInside()) {
                 insideAnyRegion = true;