com.google.common.collect

Interface MapConstraint<K,V>

@GwtCompatible
@Beta
public interface MapConstraint<K,V>

A constraint on the keys and values that may be added to a Map or Multimap. For example, MapConstraints.notNull(), which prevents a map from including any null keys or values, could be implemented like this:

   public void checkKeyValue(Object key, Object value) {
     if (key == null || value == null) {
       throw new NullPointerException();
     }
   }

In order to be effective, constraints should be deterministic; that is, they should not depend on state that can change (such as external state, random variables, and time) and should only depend on the value of the passed-in key and value. A non-deterministic constraint cannot reliably enforce that all the collection's elements meet the constraint, since the constraint is only enforced when elements are added.

Since:

3.0

Author:

Mike Bostock

See Also:

MapConstraints, Constraint

Method Summary

Methods

Modifier and Type	Method and Description
void	checkKeyValue(K key, V value) Throws a suitable RuntimeException if the specified key or value is illegal.
String	toString() Returns a brief human readable description of this constraint, such as "Not null".

Method Detail

checkKeyValue

void checkKeyValue(@Nullable
                 K key,
                 @Nullable
                 V value)

Throws a suitable RuntimeException if the specified key or value is illegal. Typically this is either a NullPointerException, an IllegalArgumentException, or a ClassCastException, though an application-specific exception class may be used if appropriate.

toString

String toString()

Returns a brief human readable description of this constraint, such as "Not null".

Overrides:

toString in class Object

Returns:

a string representation of the object.