added in API level 21



Int64Ref A signed 64bit integer reference suitable for passing to lower-level system calls. 
Os Access to low-level system functionality. 
OsConstants Constants and helper functions for use with Os
StructPollfd Used as an in/out parameter to poll(StructPollfd[], int)
StructStat File information returned by fstat(FileDescriptor), lstat(String), and stat(String)
StructStatVfs File information returned by fstatvfs(FileDescriptor) and statvfs(String)
StructTimespec Corresponds to C's struct timespec from <time.h>
StructUtsname Information returned by uname()


ErrnoException A checked exception thrown when Os methods fail.