import org.apache.commons.collections.CollectionUtils;
import org.apache.commons.lang.StringUtils;
import java.util.ArrayList;
import java.util.List;
/**
* @Desc
**/
public class Test8 {
public static void main(String[] args) {
List<String> list = new ArrayList<String>();
System.out.println(list == null);//false
String s = StringUtils.join(list, ",");//一定要注意,此时字符串s不为空,是""。吃了大亏!
System.out.println(s == null);//false
System.out.println(s.length());//0
s = CollectionUtils.isEmpty(list) ? null : StringUtils.join(list, ",");//先判断原list是否为空
System.out.println(s == null);//true
list.add("a");
s = StringUtils.join(list, ",");
System.out.println(s);/
StringUtils.join,原集合为空,结果不为空
最新推荐文章于 2024-11-19 16:02:33 发布