org.testatoo.config.SingletonProvider Maven / Gradle / Ivy
/**
* Copyright (C) 2008 Ovea
*
* Licensed 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 org.testatoo.config;
/**
* Wrapper for {@link org.testatoo.config.Provider} which returns always the same
* instance, as a singleton
*
* Example:
* {@code Provider singleton = SingletonProvider.from(container);}
*/
public abstract class SingletonProvider implements Provider {
private T instance;
@Override
public final T get() {
if (instance == null) {
instance = create();
}
return instance;
}
protected abstract T create();
/**
* Wrap the given {@link org.testatoo.config.Provider} to return always the same instance all the time. like a singleton.
*
* @param provider The provider to wrap
* @param Type of object returned
* @return A {@link org.testatoo.config.Provider} that will always returns the same instance
*/
public static SingletonProvider from(final Provider provider) {
if (provider == null) {
return null;
}
return new SingletonProvider() {
@Override
protected T create() {
return provider.get();
}
};
}
}