java: diamond operator is not supported in -source 1.5

Error:(43, 20) java: diamond operator is not supported in -source 1.5
  (use -source 7 or higher to enable diamond operator)

总共要检查4个地方,

Project Structure->Project(设置图中两处Project SDK与Project language level)

Project Structure->Modules(设置图中1处Language Level)

Java Compiler设置为8