com.electronwill.nightconfig.core.serde

Class TypeConstraint

java.lang.Object

com.electronwill.nightconfig.core.serde.TypeConstraint

public final class TypeConstraint
extends java.lang.Object

Represents a type constraint that must be satisfied by the serialization/deserialization process.

Constructor Summary

Constructors

Constructor and Description
TypeConstraint(java.lang.reflect.Type fullType) Creates a new TypeConstraint from a Type.

Method Summary

Modifier and Type	Method and Description
java.lang.reflect.Type	getFullType() Returns a Type that represents the full type constraint.
java.util.Optional<java.lang.Class<?>>	getSatisfyingRawType() Returns a Class that can satisfy the type constraint, if it can be found.
java.util.Optional<TypeConstraint[]>	resolveTypeArgumentsFor(java.lang.Class<?> classToFind) Inspects this type constraint and attempts to resolve the type arguments that have been applied to the given class, inside of the constraint.
java.lang.String	toString()

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

TypeConstraint

public TypeConstraint(java.lang.reflect.Type fullType)

Creates a new TypeConstraint from a Type.

Parameters:

fullType - the type to match

Method Detail

getFullType

public java.lang.reflect.Type getFullType()

Returns a Type that represents the full type constraint.

For instance, it can return a WildcardType with lower and/or upper bounds, like ? extends Bound, or a parameterized type with generic type arguments like Map<String, ? extends Iterable<Object>>.

Returns:

the full type constraint

getSatisfyingRawType

public java.util.Optional<java.lang.Class<?>> getSatisfyingRawType()

Returns a Class that can satisfy the type constraint, if it can be found. If no such class can be found, an empty optional is returned.

An empty optional can be returned if the type constraint is a wildcard type or a type variable with multiple bounds, such as ? super B1 extends B2 or T extends B1 & B2, in which case it's not enough to select a bound, one must find a satisfying intersection. It would be difficult to know every possible class, and there could be multiple solutions anyway.

Returns:

a class that can satisfy the type constraint, if it can be found

resolveTypeArgumentsFor

public java.util.Optional<TypeConstraint[]> resolveTypeArgumentsFor(java.lang.Class<?> classToFind)

Inspects this type constraint and attempts to resolve the type arguments that have been applied to the given class, inside of the constraint. Returns an empty optional if not found.

For instance, given a class like this:

 
 class Cls extends  MyCollection<String> {}
 class MyCollection implements  Collection<String> {}
 
 

You can expect the following result:

 
 TypeConstraint t = new TypeConstraint(Cls.class);
  Optional<TypeConstraint[]> args = t.resolveTypeArgumentsFor(Collection.class);
 Type collectionValueType = args.get()[0].getFullType();
 assertEquals(String.class, collectionValueType);
 
 

It can also resolve type variables used in field declarations.

 
 class  Cls<T extends Collection<String> & OtherBound> {
     T field;
 }
 
 

 
 Field f = Cls.class.getDeclaredField("field");
 TypeConstraint t = new TypeConstraint(f.getGenericType());
  Optional<TypeConstraint[]> args = t.resolveTypeArgumentsFor(Collection.class);
 Type collectionValueType = args.get()[0].getFullType();
 assertEquals(String.class, collectionValueType);
 
 

Parameters:

classToFind - the class to find

Returns:

the actual type arguments provided to the given class, if found

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object