package com.qs.cost.common.utils; import java.util.*; /** * 常用数据工具类 * * @Author JcYen * @Date 2019/5/23 * @Version 1.0 */ public class CollectionUtil { private CollectionUtil() { super(); } /** * 判断一个集合是否为空 */ public static boolean isEmpty(Collection col) { if (col == null || col.isEmpty()) { return true; } return false; } public static List setToList(Set colSet){ if (colSet == null || colSet.isEmpty()){ return new ArrayList<>(); } List rs = new ArrayList<>(colSet); return rs; } /** * 判断一个集合是否不为空 */ public static boolean isNotEmpty(Collection col) { return !isEmpty(col); } /** * 判断Map是否为空 */ public static boolean isEmpty(Map map) { if (map == null || map.isEmpty()) { return true; } return false; } /** * 判断Map是否不为空为空 */ public static boolean isNotEmpty(Map map) { return !isEmpty(map); } /** * 去除list中的重复数据 */ public static List removeRepeat(List list) { if (isEmpty(list)) { return list; } List result = new ArrayList(); for (T e : list) { if (!result.contains(e)) { result.add(e); } } return result; } public static boolean hasNull(Object... objects){ for (int i = 0; i < objects.length; i++) { if(objects[i]==null){return true;} } return false; } public static boolean hasNotNull(Object... objects){ for (int i = 0; i < objects.length; i++) { if(objects[i]!=null){return true;} } return false; } /** * 将集合转换为String数组 */ public static String[] toArray(List list) { if (isEmpty(list)) { return null; } String[] result = new String[list.size()]; for (int i = 0; i < list.size(); i++) { result[i] = String.valueOf(list.get(i)); } return result; } /** * 将list拆分成多给指定的大小的list */ public static List> createList(List target, int size) { List> listArr = new ArrayList<>(); //获取被拆分的数组个数 int arrSize = target.size()%size==0?target.size()/size:target.size()/size+1; for(int i=0;i sub = new ArrayList(); //把指定索引数据放入到list中 for(int j=i*size;j<=size*(i+1)-1;j++) { if(j<=target.size()-1) { sub.add(target.get(j)); } } listArr.add(sub); } return listArr; } public static T selectFirst(List list){ if(isNotEmpty(list)){ return list.get(0); } return null; } }