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.util.streams; import java.util.Objects; import java.util.Optional; import com.google.common.base.Preconditions; public class Offset { public static Offset from(Optional<Integer> offset) { return offset.map(Offset::from).orElse(none()); } public static Offset none() { return new Offset(0); } public static Offset from(int offset) { Preconditions.checkArgument(offset >= 0, "offset should be positive"); return new Offset(offset); } private final int offset; private Offset(int offset) { this.offset = offset; } public int getOffset() { return offset; } @Override public final boolean equals(Object o) { if (o instanceof Offset) { Offset other = (Offset) o; return Objects.equals(this.offset, other.offset); } return false; } @Override public final int hashCode() { return Objects.hash(offset); } }