一.Cannot find getter for field
我定義的變量爲：private String mWord;但是get方法是這樣的：getmWord()
解決方法就是改成getMWord
二.警告: Schema export directory is not provided to the annotation processor
so we cannot export the schema. You can either provide `room.schemaLocation`
annotation processor argument OR set exportSchema to false.
如圖設置一下就行