CollectionIterator.java

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/*
 * Turró i Cutiller Foundation. License notice.
 * Copyright (C) 2018 Lluis Turró Cutiller <http://www.turro.org/>
 *
 * 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.
 *
 * 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.turro.collections;
 
import java.util.List;
 
public abstract class CollectionIterator<E, ID> {
 
  protected List<E> items, collection;
  protected int _total = -1;
 
  private int _page = 10, _curr = -1;
  private boolean end;
  
  public CollectionIterator(List<E> collection) {
    this.collection = collection;
  }
 
  public int getPage() {
    return _page;
  }
 
  public void setPage(int page) {
    this._page = page;
  }
  
  public void initClauses() {
    _curr = -1;
    end = false;
    _total = -1;
    getTotalCount();
  }
  
  public List<E> getItems() {
    return items;
  }
  
  public int getTotalCount() {
    if(_total == -1) {
      _total = collection.size();
    }
    return _total;
  }
  
  public List<E> getTotalItems() {
    return collection;
  }
 
  public int item() {
    return _curr;
  }
  
  public void current(int value) {
    value = (value * _page) - _page;
    if(value >= _total) {
      value = _total - _page;
      end = true;
    }
    if(value < 0) {
      _curr = 0;
    } else {
      _curr = value;
    }
    loadItems();
  }
  
  public int current() {
    if(_curr > -1) {
      return (int) Math.ceil((_curr) / (_page + 0.0d));
    }
    return -1;
  }
  
  public int pages() {
    if(_total > -1) {
      return (int) Math.ceil((_total + 0.0d) / (_page + 0.0d));
    }
    return -1;
  }
  
  public boolean beginning() {
    return _curr <= 0;
  }
  
  public boolean end() {
    return end;
  }
  
  public void next() {
    current(current() + 1);
  }
 
  public void previous() {
    current(current() - 1);
  }
 
  public boolean isEmpty() {
    return items == null || items.isEmpty();
  }
  
  private void loadItems() {
    items = collection.subList(_curr, Math.min(_curr + _page, _total));
  }
  
}