android data binding: how to get useful error messages

Question

In android studio 2.1, the compile time error messages from xml mistakes are entirely non-helpful:

Error:(11, 41) error: package mypackage.databinding does not exist Error:(15, 13) error: cannot find symbol class MyActivityBinding 

The real error would usually be something like "there's no such attribute android:adapter", or "variable foo doesn't contain property bar" or something like that. But instead of actually showing such errors, it shows the above unhelpful ones, which only tell you that the bindings weren't generated because of some unknown error.

Answer 1

The way I use in Android Studio 4.0:

1. Select the top level Build: failed item on the Build Output panel

   

2. On the right part click Run with --stacktrace. When build is finished select the top Build: failed item again on the left panel. You'll get a databinding error description on the right panel:

   In my case it's:

   [databinding] {"msg":"Cannot find a getter for \u003ccom.google.android.material.slider.Slider app:value\u003e that accepts parameter type \u0027java.lang.Float\u0027\n\nIf a binding adapter provides the getter, check that the adapter is annotated correctly and that the parameter type matches.","file":"SliderDatabinding\src\main\res\layout\activity_main.xml","pos":[{"line0":14,"col0":8,"line1":21,"col1":41}]}