Types

Methods and classes for handling types in Java.

The types of types that are handled by the classes in this library are

• Class
• ParameterizedType
• WildcardType
• TypeVariable
• GenericArrayType

and primitive types.

Most of the functionality is offered via utility methods in the Types class. This class allows creating complex types using a fluent interface:

// Build the type "List<? extends Number>" type
 Type listWithSubtypeOfNumber = Types
     .create(List.class)
     .withSubtypeOf(Number.class)
     .build();

It also offers a functionality to parse complex types from strings:

 Type listWithIntegers = 
     Types.parse("java.util.List<java.lang.Integer>");
 Type listWithStrings = 
     Types.parse("java.util.List<java.lang.String>");

And finally, it offers a method to test whether such types are assignable:

System.out.println(Types.isAssignable(
    listWithSubtypeOfNumber, listWithIntegers)); // true
System.out.println(Types.isAssignable(
    listWithSubtypeOfNumber, listWithStrings));  // false

Additionally, the PrimitiveTypes class offers methods to handle primitive types like int or float, and their reference type counterparts like Integer or Float. For example, it also contains a method that checks whether primitive types are assignable via widening primitive conversion, according to the Java Language Specification:

System.out.println(PrimitiveTypes.isPrimitiveAssignableWithAutoboxing(
    double.class, float.class)); // true
System.out.println(PrimitiveTypes.isPrimitiveAssignableWithAutoboxing(
    float.class, Float.class));  // true
System.out.println(PrimitiveTypes.isPrimitiveAssignableWithAutoboxing(
    double.class, Float.class)); // false
System.out.println(PrimitiveTypes.isPrimitiveAssignableWithAutoboxing(
    short.class, int.class));    // false