com.hazelcast.jet.accumulator.MutableReference Maven / Gradle / Ivy
/*
* Copyright (c) 2008-2018, Hazelcast, Inc. All Rights Reserved.
*
* 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 com.hazelcast.jet.accumulator;
import java.util.Objects;
/**
* Mutable container of an object reference.
*
* @param referenced object type
*/
public class MutableReference {
private T value;
/**
* Creates a new instance with a {@code null} value.
*/
public MutableReference() {
}
/**
* Creates a new instance with the specified value.
*/
public MutableReference(T value) {
this.value = value;
}
/**
* Returns the current value.
*/
public T get() {
return value;
}
/**
* Returns {@code true} if the current value is not null, {@code false}
* otherwise.
*/
public boolean isPresent() {
return value != null;
}
/**
* Sets the value as given.
*/
public MutableReference set(T value) {
this.value = value;
return this;
}
@Override
public boolean equals(Object o) {
return this == o ||
o != null
&& this.getClass() == o.getClass()
&& Objects.equals(this.value, ((MutableReference) o).value);
}
@Override
public int hashCode() {
return value != null ? value.hashCode() : 0;
}
@Override
public String toString() {
return "MutableReference(" + value + ')';
}
}