No,we cannot access private data outside of class in java.
There is only compile time checking and no runtime check in 
java because Java supports concepts like Polymorphism and 
reflection where on runtime certain decisions are taken

This is a compile time activities, the scopes and the access
issues are handled at the compile time and this exception is
not the subclas of the runtime exception class and doesnt go
unchecked during compile time, they are checked at compile
time and the compile time exceptions are checked exceptions
which are checked by the compiler before hand and the
example of runtime exception is say bad logic like array
having -ve size and division by zero where actual excecution
occurs in JRE of the byte code.