com.davidbracewell.conversion.Cast Maven / Gradle / Ivy
Go to download
Show more of this group Show more artifacts with this name
Show all versions of mango Show documentation
Show all versions of mango Show documentation
A set of utilities and tools to speed up and ease programming in Java.
/*
* (c) 2005 David B. Bracewell
*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
package com.davidbracewell.conversion;
import com.davidbracewell.function.SerializableFunction;
import com.google.common.base.Preconditions;
import lombok.NonNull;
import java.io.Serializable;
import java.util.*;
/**
* A collection of static methods making casting from one type to another a bit easier. Note that the standard use
* case for the collection based conversions are for use in for loops or method calls where the collection is read
* only.
* Note that these methods only cast and do not convert, i.e. an Integer object cannot be cast to a Double object.
* If conversion is needed then transformations should be done using Guava or the Converter class.
*
* @author David B. Bracewell
*/
public final class Cast {
private Cast() {
}
/**
* Casts an object in an unchecked manner.
*
* @param the type parameter
* @param o the object
* @return the casted object or null if the object was null
*/
@SuppressWarnings("unchecked")
public static T as(Object o) {
return o == null ? null : (T) o;
}
/**
* Casts an object in a checked manner.
*
* @param the type parameter
* @param o the object
* @param clazz The class to cast to
* @return the casted object or null if the object was null or the object was not of the desired type
*/
public static T as(Object o, Class clazz) {
Preconditions.checkNotNull(clazz);
try {
return o == null ? null : clazz.cast(o);
} catch (Exception e) {
return null;
}
}
/**
* Creates a casting function that casts objects from one type to another using {@link #as(Object)}.
*
* @param the type parameter
* @param the type parameter
* @return A Function for casting objects to other types
*/
public static SerializableFunction castingFunction() {
return input -> Cast.as(input);
}
/**
* Creates a casting function that casts objects from one type to another using {@link #as(Object, Class)}.
*
* @param the type parameter
* @param the type parameter
* @param clazz The class to cast to
* @return A Function for casting objects to other types
*/
public static SerializableFunction castingFunction(@NonNull final Class clazz) {
return input -> Cast.as(input, clazz);
}
/**
* Casts the elements in an iterable in a lazy fashion. Calls to remove on the iterator will be reflected in
* iterable
*
* @param the type parameter
* @param iterable the iterable
* @return the casted iterable or null if the given iterable is null
*/
public static Iterable cast(Iterable iterable) {
return iterable == null ? null : new CastingIterable(iterable);
}
/**
* Casts the elements in a set in a lazy fashion. Changes to the returned set are reflected in the the given
* set.
*
* @param the type parameter
* @param set the set
* @return the casted set or null if the given set is null
*/
public static Set cast(Set set) {
return set == null ? null : new CastingSet(set);
}
/**
* Casts the elements in a list in a lazy fashion. Changes to the returned list are reflected in the the given
* list.
*
* @param the type parameter
* @param list the list to cast
* @return the casted list or null if the given list is null
*/
public static List cast(List list) {
return list == null ? null : new CastingList(list);
}
/**
* Casts the elements in an iterator in a lazy fashion. Changes to the returned iterator are reflected in the the
* given iterator.
*
* @param the type parameter
* @param iterator the iterator to cast
* @return the casted iterator or null if the given iterator was null
*/
public static Iterator cast(Iterator iterator) {
return iterator == null ? null : new CastingIterator(iterator);
}
/**
* Casts the elements in a collection in a lazy fashion. Changes to the returned collection are reflected in the
* the given collection.
*
* @param the type parameter
* @param collection the collection to cast
* @return the casted collection or null if the collection is null
*/
public static Collection cast(Collection collection) {
return collection == null ? null : new CastingCollection(collection);
}
/**
* Casts a map in a lazy fashion. Changes to the returned map are reflected in the
* the given map.
*
* @param the type parameter
* @param the type parameter
* @param map the map to cast
* @return the casted map or null if the map is null
*/
public static Map cast(Map map) {
return map == null ? null : new CastingMap(map);
}
private static class CastingMap extends AbstractMap implements Serializable {
private static final long serialVersionUID = -2611216527976365947L;
private final Map map;
private CastingMap(Map map) {
this.map = map;
}
@Override
public Set> entrySet() {
return new CastingSet<>(map.entrySet());
}
}//END OF Cast$CastingMap
private static class CastingCollection extends AbstractCollection implements Serializable {
private static final long serialVersionUID = 7649013713070530029L;
private final Collection wrap;
private CastingCollection(Collection wrap) {
this.wrap = wrap;
}
@Override
public Iterator iterator() {
return new CastingIterator<>(wrap.iterator());
}
@Override
public int size() {
return wrap.size();
}
}//END OF Cast$CastingCollection
private static class CastingList extends AbstractList implements Serializable {
private static final long serialVersionUID = -5983768563529915927L;
private final List wrap;
private CastingList(List wrap) {
this.wrap = wrap;
}
@Override
public V get(int index) {
return Cast.as(wrap.get(index));
}
@Override
public int size() {
return wrap.size();
}
}//END OF Cast$CastingList
private static class CastingIterable implements Iterable, Serializable {
private static final long serialVersionUID = 4904704966440313023L;
private final Iterable wrap;
private CastingIterable(Iterable wrap) {
this.wrap = wrap;
}
@Override
public Iterator iterator() {
return new CastingIterator<>(wrap.iterator());
}
}//END OF Cast$CastingIterable
private static class CastingIterator implements Iterator, Serializable {
private static final long serialVersionUID = -6524171187233137692L;
private final Iterator wrap;
private CastingIterator(Iterator wrap) {
this.wrap = wrap;
}
@Override
public boolean hasNext() {
return wrap.hasNext();
}
@Override
public V next() {
return as(wrap.next());
}
@Override
public void remove() {
wrap.remove();
}
}//END OF Cast$CastingIterator
private static class CastingSet extends AbstractSet implements Serializable {
private static final long serialVersionUID = 8015953484790512598L;
private final Set wrap;
private CastingSet(Set wrap) {
this.wrap = wrap;
}
@Override
public Iterator iterator() {
return new CastingIterator<>(wrap.iterator());
}
@Override
public int size() {
return wrap.size();
}
}//END OF Cast$CastingSet
}//END OF Cast
© 2015 - 2025 Weber Informatics LLC | Privacy Policy