preemptive and nonpreemptive data types code example

Example: non primitive data types in java

Non-Primitive Data Types: These data types are not actually defined by 
the programming language but are created by the programmer. They are 
also called “reference variables” or “object references” since they 
refer to a memory location which stores the data.
  
All classes are non-primitive data types.
Example : Object, String, Integer, Boolean, etc...