package com.xinda.scada.utils;

import java.util.List;

/**
 * @author fastb
 * @version 1.0
 * @description: 组态集合工具类
 * @date 2024-03-29 15:01
 */
public class ScadaCollectionUtils {

    /**
     * 开始分页
     *
     * @param list  传入的list集合
     * @param pageNum  页码
     * @param pageSize 每页多少条数据
     * @return
     */
    public static List startPage(List list, Integer pageNum,
                                 Integer pageSize) {
        if (list == null) {
            return null;
        }
        if (list.size() == 0) {
            return null;
        }
        Integer count = list.size(); // 记录总数
        Integer pageCount = 0; // 页数
        if (count % pageSize == 0) {
            pageCount = count / pageSize;
        } else {
            pageCount = count / pageSize + 1;
        }
        int fromIndex = 0; // 开始索引
        int toIndex = 0; // 结束索引
        if (!pageNum.equals(pageCount)) {
            fromIndex = (pageNum - 1) * pageSize;
            toIndex = fromIndex + pageSize;
        } else {
            fromIndex = (pageNum - 1) * pageSize;
            toIndex = count;
        }
        List pageList = list.subList(fromIndex, toIndex);
        return pageList;
    }

}
