Java之工具类：判断对象是否为空或null

import java.lang.reflect.Array;
import java.util.Collection;
import java.util.Map;

/**
 * 判断对象是否为空或null
 */
public class ObjectUtils {

    public static boolean isNull(Object obj) {
        return obj == null;
    }

    public static boolean isNotNull(Object obj) {
        return !isNull(obj);
    }

    public static boolean isEmpty(Object obj) {
        if (obj == null) return true;
        else if (obj instanceof CharSequence) return ((CharSequence) obj).length() == 0;
        else if (obj instanceof Collection) return ((Collection) obj).isEmpty();
        else if (obj instanceof Map) return ((Map) obj).isEmpty();
        else if (obj.getClass().isArray()) return Array.getLength(obj) == 0;

        return false;
    }

    public static boolean isNotEmpty(Object obj) {
        return !isEmpty(obj);
    }
}