"jmethodID was NULL" error when calling DeviceManager.initialiseWithDefaultDevices()

[fr810]

You may have forgotten to call Threads::initialiseJUCE before using any JUCE code. Have a look at this post which is probably helpful:

Breaking Changes in JUCE’s low-level Android code

With commit 9a4548a (on develop), we have completely re-structured JUCE’s low-level Android code. Although no public JUCE APIs (any APIs listed on docs.juce.com) have changed, this commit will likely introduce breaking changes if you used any of JUCE’s internal JNI helper macros (modules/juce_core/juce_android_JNIHelpers.h), invoked native android code directly or relied on JUCE’s auto-generated java code. Before any JUCE API function is called, you must now invoke the Threads::initialiseJUCE …