[Java] JAVA List和Map切割工具详解

import org.springframework.util.CollectionUtils;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;
/**
 * @author lanfangyi
 * @version 1.0
 * @since 2019/2/28 20:39
 */
public class CollectionUtil {
  private CollectionUtil(){
  }
  /**
   * 将map切成段，作用与PHP的array_chunk函数相当
   *
   * @param chunkMap 被切段的map
   * @param chunkNum 每段的大小
   * @param <k>   map的key类型
   * @param <v>   map的value类型 如果是自定义类型，则必须实现equals和hashCode方法
   * @return
   */
  public static <k, v> List<Map<k, v>> mapChunk(Map<k, v> chunkMap, int chunkNum) {
  if (chunkMap == null || chunkNum <= 0) {
    List<Map<k, v>> list = new ArrayList<>();
    list.add(chunkMap);
    return list;
  }
  Set<k> keySet = chunkMap.keySet();
  Iterator<k> iterator = keySet.iterator();
  int i = 1;
  List<Map<k, v>> total = new ArrayList<>();
  Map<k, v> tem = new HashMap<>();
  while (iterator.hasNext()) {
    k next = iterator.next();
    tem.put(next, chunkMap.get(next));
    if (i == chunkNum) {
    total.add(tem);
    tem = new HashMap<>();
    i = 0;
    }
    i++;
  }
  if(!CollectionUtils.isEmpty(tem)){
    total.add(tem);
  }
  return total;
  }
  /**
   * 将list切割
   *
   * @param chunkList 被分隔的数组
   * @param chunkNum 每段的大小
   * @param <T>  List中的类型
   * @return
   */
  public static <T> List<List<T>> listChunk(List<T> chunkList, int chunkNum) {
  if (chunkList == null || chunkNum <= 0) {
    List<List<T>> t = new ArrayList<>();
    t.add(chunkList);
    return t;
  }
  Iterator<T> iterator = chunkList.iterator();
  int i = 1;
  List<List<T>> total = new ArrayList<>();
  List<T> tem = new ArrayList<>();
  while (iterator.hasNext()) {
    T next = iterator.next();
    tem.add(next);
    if (i == chunkNum) {
    total.add(tem);
    tem = new ArrayList<>();
    i = 0;
    }
    i++;
  }
  if(!CollectionUtils.isEmpty(tem)){
    total.add(tem);
  }
  return total;
  }
}

List<Map<String,Object>> listMap = new ArrayList<>();
Map<String,Object> map = new HashMap<String,Object>();
List<Entity> list = new ArrayList<>();
map.put("list",list);
listMap.add(map);