Java tutorial
/**************************************************************** * 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 org.apache.james.quota.search; import java.util.Objects; import java.util.Optional; import com.google.common.base.MoreObjects; import com.google.common.base.Preconditions; public class Limit { public static Limit of(int value) { Preconditions.checkArgument(value >= 0, "A limit need to be positive"); return new Limit(Optional.of(value)); } public static Limit unlimited() { return new Limit(Optional.empty()); } private final Optional<Integer> value; private Limit(Optional<Integer> value) { this.value = value; } public Optional<Integer> getValue() { return value; } @Override public final boolean equals(Object o) { if (o instanceof Limit) { Limit limit = (Limit) o; return Objects.equals(this.value, limit.value); } return false; } @Override public final int hashCode() { return Objects.hash(value); } @Override public String toString() { return MoreObjects.toStringHelper(this).add("value", value).toString(); } }