java¶ÔÊý¾Ý¿âÖÐNULLµÄ´¦Àí
javaÖÐnullµÄ¸ÅÄî:javaÖУ¬null±íʾÀà»ò±äÁ¿Êǿգ¬²»´ú±íÈκζÔÏó»òʵÀý£¬¿ÉÒÔ½«null¸³¸øÒýÓÃÀàÐͱäÁ¿£¬µ«²»¿ÉÒÔ½«null¸³¸ø»ù±¾ÀàÐͱäÁ¿¡£Êý¾Ý¿âÖÐNULLµÄ¸ÅÄî:Êý¾Ý¿âÖУ¬null±íʾδÌîд¡¢Î´Öª¡¢²»¿ÉÓõĸÅÄºÍjava²»Í¬µÄÊÇÊý¾Ý¿âÖпÉÒÔ½«null¸³¸øÈκÎÊý¾ÝÀàÐÍ¡£ÕâÑùÒ»À´£¬ÎÒÃÇ´ÓÊý¾Ý¿âÖжÁÈ¡×ֶεÄÖµºó£¬ÔÚjava³ÌÐòÖÐÈçºÎÅж϶ÁÈ¡µÄÖµÊÇ·ñΪnullÄØ£¿ÓÃx==null·½·¨Âð£¿ÏÔÈ»²»ÐУ¬³ý·ÇÕâ¸öXÊÇStringÀàÐ͵ġ£ResultSetÖеÄwasNull()·½·¨¿ÉÒÔ½â¾öÕâ¸öÎÊÌâ:
wasNull():±¨¸æ×îºóÒ»¸ö¶ÁÈ¡µÄÁÐÊÇ·ñ¾ßÓÐÖµ SQL NULL¡£×¢Ò⣬±ØÐëÊ×ÏȶÔÁе÷ÓÃÒ»¸ö»ñÈ¡·½·¨³¢ÊÔ¶ÁÈ¡ÆäÖµ£¬È»ºóµ÷Óà wasNull ·½·¨²é¿´¶ÁÈ¡µÄÖµÊÇ·ñΪ SQL NULL¡£
È磺String value="";
int n;
while(rs.next()){
value=rs.getString("name");
if(rs.wasNull()){
System.out.println("null");
}else{
System.out.println(value);
}
n=rs.getInt("number");
if(rs.wasNull()){
System.out.println("null");
}else{
System.out.println(n);
}
}
Ïà¹ØÎĵµ£º
HTTP(Hyper-Text Transfer Protocol)Êǵ±Ç°ÒòÌØÍøÉÏʹÓÃ×î¶àµÄÐÒé¡£ÍøÂç·þÎñ£¬ÍøÂçÉ豸ÒÔ¼°ÍøÂç¼ÆËãµÄÔö³¤²»½öÔö¼ÓÁËÐèÒªHTTPÖ§³ÖµÄµÄÓ¦ÓóÌÐò£¬»¹À©Õ¹ÁËHTTPµÄ½ÇÉ«£¬Ê¹Æä²»½ö½öÓ¦ÓÃÓÚÓû§Çý¶¯µÄwebä¯ÀÀÆ÷¡£ java.net°üÌṩͨ¹ýHTTP·ÃÎÊ×ÊÔ´µÄ»ù±¾¹¦ÄÜ¡£HttpClientÉ跨ͨ¹ýʵÏÖÒ»¸ö¸ßЧµÄ£¬×îÐµģ¬¹¦ÄܷḻµÄHttp¿Í»§¶ËÀ ......
²éÁ˺ܶà×ÊÁÏ£¬×ÜËã¶Ô½Ó¿ÚµÄ¸ÅÄîÂÔ¶®ÁËÒ»µã£¬°´ÎÒ×Ô¼ºµÄÀí½â°Ñ×ÊÁÏÕûÀíÁËһϡ£
JavaÖеĽӿÚÊÇһϵÁз½·¨µÄÉùÃ÷£¬ÊÇһЩ·½·¨ÌØÕ÷µÄ¼¯ºÏ£¬Ò»¸ö½Ó¿ÚÖ»Óз½·¨µÄÌØÕ÷ûÓз½·¨µÄʵÏÖ£¬Òò´ËÕâЩ·½·¨¿ÉÒÔÔÚ²»Í¬µÄµØ·½±»²»Í¬µÄÀàʵÏÖ£¬¶øÕâЩʵÏÖ¿ÉÒÔ¾ßÓв» ......
java exception ½â¾ö·½°¸ - ÎÒµÄÒì³£Íø|Òì³£|exception|myexception 831 - ActionMessages 832 - could not instantiate id generator 833 - javax.servlet.jsp.JspException 834 - javax.naming.NoInitialContextException 835 - net.sf.hibernate.HibernateException 836 - org.hibernate.exception.GenericJDBCExceptio ......
//ÕâÊÇÎҵĶ¨Ê±Æ÷À࣬ÓÃÀ´¶¨Ê±Ö´ÐÐij¶ÎÈÎÎñ£»
package com.my.time;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Timer;
public
class
BugXmlTimer {
public
......