Java tutorial
/* * Copyright (C) 2000 - 2018 Silverpeas * * This program is free software: you can redistribute it and/or modify * it under the terms of the GNU Affero General Public License as * published by the Free Software Foundation, either version 3 of the * License, or (at your option) any later version. * * As a special exception to the terms and conditions of version 3.0 of * the GPL, you may redistribute this Program in connection with Free/Libre * Open Source Software ("FLOSS") applications as described in Silverpeas's * FLOSS exception. You should have received a copy of the text describing * the FLOSS exception, and it is also available here: * "https://www.silverpeas.org/legal/floss_exception.html" * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU Affero General Public License for more details. * * You should have received a copy of the GNU Affero General Public License * along with this program. If not, see <http://www.gnu.org/licenses/>. */ package org.silverpeas.core.util; import org.apache.commons.lang3.builder.HashCodeBuilder; import java.util.ArrayList; import java.util.Collection; import java.util.List; /** * This list represents a slice of a more complete lists and as such contains only the items that * are part of this slice. * @author mmoquillon */ public class ListSlice<T> extends ArrayList<T> implements SilverpeasList<T> { private static final long serialVersionUID = 679667310008767706L; private int start; private int end; private long maxsize = -1; /** * Constructs a new slice for a given list. * @param sliceBeginIndex the index in the original list at which this slice starts. * @param sliceEndIndex the index in the original list at which this slice should end in the list. * The value must be equal or greater than the slice beginning index; a value equal to the * beginning index means the last item index in this slice isn't yet known. * If the index of the last item in the original list is lesser than the specified index, then * this slice ends up at the index of this last item. */ public ListSlice(int sliceBeginIndex, int sliceEndIndex) { super(sliceEndIndex - sliceBeginIndex + 1); this.start = sliceBeginIndex; this.end = sliceEndIndex; } /** * Constructs a new slice for a given list. * @param sliceBeginIndex the index in the original list at which this slice starts. * @param sliceEndIndex the index in the original list at which this slice should end in the list. * The value must be equal or greater than the slice beginning index; a value equal to the * beginning index means the last item index in this slice isn't yet known. * If the index of the last item in the original list is lesser than the specified index, then * this slice ends up at the index of this last item. * @param originalListSize the size of the original list this slice comes from. It must be greater * than 0. */ public ListSlice(int sliceBeginIndex, int sliceEndIndex, long originalListSize) { this(sliceBeginIndex, sliceEndIndex); if (originalListSize <= 0) { throw new AssertionError(); } this.maxsize = originalListSize; } /** * Constructs a new slice for a given list. * @param sliceBeginIndex the index in the original list at which this slice starts. * @param sliceEndIndex the index in the original list at which this slice should end in the list. * If the index of the last item in the original list is lesser than the specified index, then * this slice ends up at the index of this last item. If this index is the same than the beginning * index then the slice is empty. * @param originalList the original list from which this slice comes from. */ public ListSlice(int sliceBeginIndex, int sliceEndIndex, List<? extends T> originalList) { super(originalList.subList(sliceBeginIndex, sliceEndIndex)); this.start = sliceBeginIndex; this.end = sliceEndIndex; this.maxsize = originalList.size(); } /** * Constructs a new list slice with all the items of the specified collection. This slice will * contain the items of the whole specified collection and as such the original list size is equal * to its real size. * @param collection a collection of items of type T */ public ListSlice(Collection<? extends T> collection) { super(collection); this.start = 0; this.end = collection.isEmpty() ? 0 : collection.size() - 1; this.maxsize = collection.size(); } @Override public <U> SilverpeasList<U> newEmptyListWithSameProperties() { final ListSlice<U> newEmptyList = new ListSlice<>(this.start, this.end); newEmptyList.setOriginalListSize(this.maxsize); return newEmptyList; } /** * Gets the first index of this slice in the original list from which it comes. It is the * inclusive index at which this slice begins in the original list. * @return the index at which this slice begins in the original list. */ public int getFirstIndex() { return start; } /** * Gets the last index of this slice in the original list from which it comes. It is the * inclusive index at which this slice ends in the original list. * @return the index at which this slice ends in the original list. */ public int getLastIndex() { if (end > start && end < size()) { return end; } return isEmpty() ? 0 : size() - 1; } /** * Gets the size of the original list this slice comes from. If this slice covers all the original * list then {@code originalListSize() == size()}. The size of the original list can be * unknown at the time the slice is built, in this case -1 is returned. * @return the size of the original list or -1 if such a size isn't known. */ @Override public long originalListSize() { return maxsize; } /** * Sets the size of the original list this slice comes from. * @param size the size of the original list */ public void setOriginalListSize(long size) { this.maxsize = size; } @Override public boolean equals(final Object o) { if (this == o) { return true; } if (!(o instanceof ListSlice)) { return false; } if (!super.equals(o)) { return false; } final ListSlice<?> listSlice = (ListSlice<?>) o; if (start != listSlice.start) { return false; } if (end != listSlice.end) { return false; } if (maxsize != listSlice.maxsize) { return false; } return super.equals(listSlice); } @Override public int hashCode() { return new HashCodeBuilder().append(start).append(end).append(maxsize).append(super.hashCode()) .toHashCode(); } }