Interface Type

  • All Superinterfaces:
    AnnotationTarget
    All Known Subinterfaces:
    ArrayType, ClassType, ParameterizedType, PrimitiveType, TypeVariable, VoidType, WildcardType

    public interface Type
    extends AnnotationTarget
    A type is used in a program source code, but does not have to be declared anywhere.

    For example, the int type exists even if it is not declared in any Java source file, while the java.lang.String type is declared by the class of the same name. Array types, such as int[] or String[][], are not declared anywhere either, but their element types may be. A generic class, such as java.util.List, declares a raw type of the same name, but it does not declare the parameterized types, such as List<String>. Parameterized types are created by applying type arguments to generic classes. For example, the List<String> type is created by applying String to List<T>.

    Types occur on many places. A field has a type, a method has a return type, a method parameter has a type, even the extends clause in a class declaration contains a type. Occurences of types may be annotated.

    Types are:

    • the void pseudo-type
    • a primitive type, such as int
    • a class type, such as String
    • an array type, such as int[] or String[][]
    • a parameterized type, such as List<String>
    • a type variable, such as T when used in a class that declares a type parameter T
    • a wildcard type, such as the type argument in List<? extends Number>
    Class types and parameterized types allow obtaining their class declarations.
    • Method Detail

      • isType

        default boolean isType()
        Description copied from interface: AnnotationTarget
        Returns whether this annotation target is a type.
        Specified by:
        isType in interface AnnotationTarget
        Returns:
        true if this is a type, false otherwise
      • kind

        Type.Kind kind()
        Returns the kind of this type.
        Returns:
        the kind of this type
      • isVoid

        default boolean isVoid()
        Returns whether this type is the void pseudo-type.
        Returns:
        true if this is void, false otherwise
      • isPrimitive

        default boolean isPrimitive()
        Returns whether this type is a primitive type.
        Returns:
        true if this is a primitive type, false otherwise
      • isClass

        default boolean isClass()
        Returns whether this type is a class type.
        Returns:
        true if this is a class type, false otherwise
      • isArray

        default boolean isArray()
        Returns whether this type is an array type.
        Returns:
        true if this is an array type, false otherwise
      • isParameterizedType

        default boolean isParameterizedType()
        Returns whether this type is a parameterized type.
        Returns:
        true if this is a parameterized type, false otherwise
      • isTypeVariable

        default boolean isTypeVariable()
        Returns whether this type is a type variable. Type variables are also used to represent type parameters in declarations of parameterized types.
        Returns:
        true if this is a primitive type, false otherwise
      • isWildcardType

        default boolean isWildcardType()
        Returns whether this type is a wildcard type.
        Returns:
        true if this is a wildcard type, false otherwise