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;
public class 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;
}
}
标签:Map,JAVA,tem,iterator,List,chunkNum,new,total From: https://blog.51cto.com/chengzheng183/6350525