反复时采纳前面的value 笼罩后面的value
Map<String, String> map = list.stream().collect(Collectors.toMap(Student :: getClassName, Student :: getStudentName, (value1, value2 )->{ return value2; }));
反复时采纳前面的value 笼罩后面的value
Map<String, String> map = list.stream().collect(Collectors.toMap(Student :: getClassName, Student :: getStudentName, (value1, value2 )->{ return value2; }));