com.blazebit.persistence.PagedArrayList Maven / Gradle / Ivy
/*
* Copyright 2014 - 2021 Blazebit.
*
* 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.blazebit.persistence;
import java.util.ArrayList;
import java.util.Collection;
/**
* A simple implementation of {@link PagedList} based on {@link ArrayList}.
*
* @param the type of elements in this list
* @author Christian Beikov
* @author Moritz Becker
* @since 1.2.0
*/
public class PagedArrayList extends ArrayList implements PagedList {
private static final long serialVersionUID = 1L;
private final KeysetPage keyset;
private final long totalSize;
private final int page;
private final int totalPages;
private final int firstResult;
private final int maxResults;
/**
* Constructs a new empty paged array list.
*
* @param keyset The keyset page for this page
* @param totalSize The total size of the result
* @param firstResult The first result index within the overall result
* @param maxResults The maximum result count for a page
*/
public PagedArrayList(KeysetPage keyset, long totalSize, int firstResult, int maxResults) {
this.keyset = keyset;
this.totalSize = totalSize;
this.page = (int) Math.floor((firstResult == -1 ? 0 : firstResult) * 1d / maxResults) + 1;
this.totalPages = totalSize < 1 ? 0 : (int) Math.ceil(totalSize * 1d / maxResults);
this.firstResult = firstResult;
this.maxResults = maxResults;
}
/**
* Constructs a new paged array list from the given collection.
*
* @param collection The collection of elements for this page
* @param keyset The keyset page for this page
* @param totalSize The total size of the result
* @param firstResult The first result index within the overall result
* @param maxResults The maximum result count for a page
*/
public PagedArrayList(Collection collection, KeysetPage keyset, long totalSize, int firstResult, int maxResults) {
super(collection);
this.keyset = keyset;
this.totalSize = totalSize;
this.page = (int) Math.floor((firstResult == -1 ? 0 : firstResult) * 1d / maxResults) + 1;
this.totalPages = totalSize < 1 ? 0 : (int) Math.ceil(totalSize * 1d / maxResults);
this.firstResult = firstResult;
this.maxResults = maxResults;
}
@Override
public int getSize() {
return size();
}
@Override
public long getTotalSize() {
return totalSize;
}
@Override
public int getPage() {
return page;
}
@Override
public int getTotalPages() {
return totalPages;
}
@Override
public int getFirstResult() {
return firstResult;
}
@Override
public int getMaxResults() {
return maxResults;
}
@Override
public KeysetPage getKeysetPage() {
return keyset;
}
}