After the dex file is mapped to memory, it will call function
dexFileParse to parse this memory, and the parse result is
stored into a data structure named DexFile. The baseAddr of
DexFile points to the start address of the mapped memory,
pClassDefs points to the start address of ClassDefs which is the
index of classes. System will use the class name to get the
location of classes. In order to speed up the locating process, a
hash table will be created. While loading classes, compute the
hash value of the class name and using it to get the location of
this class while running. Though it will spend more time in
loading it will save a lot of time in running. In Dalvik,
ClassObject will store the loaded class information.