Necessity to compile for VERSION_1_8

It might be worth adding to the instructions to use this, the need for adding

+    compileOptions {
+        targetCompatibility JavaVersion.VERSION_1_8
+        sourceCompatibility JavaVersion.VERSION_1_8
+    }

to the gradle files for all the modules that include this. I was getting a fairly cryptic error code com.android.dx.cf.code.SimException: invalid opcode ba (invokedynamic requires --min-sdk-version >= 26) that I eventually tracked down to this. Alternatively, I’m not sure how necessary the lambda expression in BleManager is since without that this restriction might not be required.

[philips77]

Whaaaaat? No one reads readme?! I’ll rename it to Pleasereadme or Youdbetterreadme 😉

PS. Ok, I’ll put it higher in the TL;DR section.

[stanleyguevara]

I think it’s still worth mentioning somewhere in the readme.

I’ve bumped into it on latest Android Studio (3.5.2 on Win10) with fresh project straight from the wizard (though AS install is pretty old, maybe it has default somewhere to not use 1.8, IDK).

Simply adding the library to gradle.build was causing quite cryptic crash: ClassNotFoundException: Didn't find class "com.test.MainActivity" on path: DexPathList

Took a while to discover it was the lib in first place, as it wasn’t crashing on API 28, only few commits later when running on API 26 it started crashing…

Edit: Now I see it’s a last point in readme under Changes in version 2.0, super easy to miss. It’d really be better if it would be more like “Remember to add”:

    compileOptions {
        sourceCompatibility JavaVersion.VERSION_1_8
        targetCompatibility JavaVersion.VERSION_1_8
    }

placed directly under implementation 'no.nordicsemi.android:ble:2.1.1', as I’m pretty sure no one reads the whole readme 😃