Java中判断list为空(CollectionUtils.isEmpty)

Java中判断list为空(CollectionUtils.isEmpty)

https://blog.csdn.net/zhuoya_/article/details/104621126

1. @Test
2. public void testStr() {
3. /*----------------【Start】isEmpty方法检查-----------------*/
4. List strList1 = Lists.newArrayList();
5. System.out.println(CollectionUtils.isEmpty(strList1));//true
6. System.out.println(CollectionUtils.isEmpty(new ArrayList()));//true
7. System.out.println(strList1 == null);//false
8. System.out.println(strList1.size());//0
10. List strList2 = new ArrayList<>();
11. System.out.println(strList2 == null);//false
12. strList2=null;
13. System.out.println(strList2 == null);//true
14. System.out.println(CollectionUtils.isEmpty(strList2));//true
15. /*----------------【END】isEmpty方法检查-----------------*/
16. }

import org.springframework.util.CollectionUtils;


总结：

1：刚创建出来的List长度为0，但不为null

2：CollectionUtils.isEmpty()方法可以检查null和长度为0的list