Java之工具类：判断对象是否为空或null

 1 import java.lang.reflect.Array;
 2 import java.util.Collection;
 3 import java.util.Map;
 4 
 5 /**
 6  * 判断对象是否为空或null
 7  */
 8 public class ObjectUtils {
 9 
10     public static boolean isNull(Object obj) {
11         return obj == null;
12     }
13 
14     public static boolean isNotNull(Object obj) {
15         return !isNull(obj);
16     }
17 
18     public static boolean isEmpty(Object obj) {
19         if (obj == null) return true;
20         else if (obj instanceof CharSequence) return ((CharSequence) obj).length() == 0;
21         else if (obj instanceof Collection) return ((Collection) obj).isEmpty();
22         else if (obj instanceof Map) return ((Map) obj).isEmpty();
23         else if (obj.getClass().isArray()) return Array.getLength(obj) == 0;
24 
25         return false;
26     }
27 
28     public static boolean isNotEmpty(Object obj) {
29         return !isEmpty(obj);
30     }
31 }