写了个demo，一直报错
Caused by: java.lang.IllegalStateException: Required view 'tv1' with ID 2131492943 for field 'textView' was not found. If this view is optional add 'Nullable' annotation.
检查很多遍，原因是因为把b i n d（ t h i s）写到了setContentView前面，，导致无法绑定View