The import statements must follow the package statement. import
statements should be sorted with the most fundamental packages first,
and grouped with associated packages together and one blank line
between groups.

….. …..

The import statement location is enforced by the Java
language. The sorting makes it simple to browse the list when there
are many imports,and it makes it easy to determine the dependiencies
of the present package The grouping reduce complexity by collapsing
related information into a common unit.

参考Java Tutorial链接了解更多信息.