Generic

By Tiationg Kho |
Tags:

Generic

  • Generics enable types (classes and interfaces) to be parameters when defining classes, interfaces, and methods
  • Pros
    • Stronger type checks at compile time
    • No casting needed
    • Ability to implement generic algorithms
  • Declare Generics
    • Generic class
      • class Name<T1, T2, ...> { /* ... */ }
    • Generic method
      • public <T1, T2, ...> returnType methodName(T1 param) { /* ... */ }
  • Generics Type Parameters
    • They must be defined in the class or method signature
    • Naming convention
      • E for element (used extensively by the Java Collections Framework)
      • K for key, and V for value
      • N for number
      • T for type
  • Bound on Type Parameters
    • eg. <T extends Number> limits the type parameter T to subclasses of Number
  • Wildcards
    • ? for unknown type