Ò׽ؽØÍ¼Èí¼þ¡¢µ¥Îļþ¡¢Ãâ°²×°¡¢´¿ÂÌÉ«¡¢½ö160KB

È«Ãæ½âÎöJavaÖеÄStringÊý¾ÝÀàÐÍ

1. Ê×ÏÈString²»ÊôÓÚ8ÖÖ»ù±¾Êý¾ÝÀàÐÍ£¬StringÊÇÒ»¸ö¶ÔÏó¡£
ÒòΪ¶ÔÏóµÄĬÈÏÖµÊÇnull£¬ËùÒÔStringµÄĬÈÏÖµÒ²ÊÇnull£»µ«ËüÓÖÊÇÒ»ÖÖÌØÊâµÄ¶ÔÏó£¬ÓÐÆäËü¶ÔÏóûÓеÄÒ»Ð©ÌØÐÔ¡£
2. new String()ºÍnew String(“”)¶¼ÊÇÉêÃ÷Ò»¸öеĿÕ×Ö·û´®£¬Êǿմ®²»ÊÇnull£»
3. String str=”kvill”£»
String str=new String (“kvill”);µÄÇø±ð£º
ÔÚÕâÀÎÒÃDz»Ì¸¶Ñ£¬Ò²²»Ì¸Õ»£¬Ö»Ïȼòµ¥ÒýÈë³£Á¿³ØÕâ¸ö¼òµ¥µÄ¸ÅÄî¡£
³£Á¿³Ø(constant pool)Ö¸µÄÊÇÔÚ±àÒëÆÚ±»È·¶¨£¬²¢±»±£´æÔÚÒѱàÒëµÄ.classÎļþÖеÄһЩÊý¾Ý¡£Ëü°üÀ¨Á˹ØÓÚÀà¡¢·½·¨¡¢½Ó¿ÚµÈÖеij£Á¿£¬Ò²°üÀ¨×Ö·û´®³£Á¿¡£
¿´Àý1£º
String s0=”kvill”;
String s1=”kvill”;
String s2=”kv” + “ill”;
System.out.println( s0==s1 );
System.out.println( s0==s2 );
½á¹ûΪ£º
true
true
Ê×ÏÈ£¬ÎÒÃÇÒªÖª½á¹ûΪµÀJava»áÈ·±£Ò»¸ö×Ö·û´®³£Á¿Ö»ÓÐÒ»¸ö¿½±´¡£
ÒòΪÀý×ÓÖеÄs0ºÍs1ÖеĔkvill”¶¼ÊÇ×Ö·û´®³£Á¿£¬ËüÃÇÔÚ±àÒëÆÚ¾Í±»È·¶¨ÁË£¬ËùÒÔs0==s1Ϊtrue£»¶ø”kv”ºÍ”ill”Ò²¶¼ÊÇ×Ö·û´®³£Á¿£¬µ±Ò»¸ö×Ö·û´®Óɶà¸ö×Ö·û´®³£Á¿Á¬½Ó¶ø³Éʱ£¬Ëü×Ô¼º¿Ï¶¨Ò²ÊÇ×Ö·û´®³£Á¿£¬ËùÒÔs2ҲͬÑùÔÚ±àÒëÆÚ¾Í±»½âÎöΪһ¸ö×Ö·û´®³£Á¿£¬ËùÒÔs2Ò²Êdz£Á¿³ØÖДkvill”µÄÒ»¸öÒýÓá£
ËùÒÔÎÒÃǵóös0==s1==s2;
ÓÃnew String() ´´½¨µÄ×Ö·û´®²»Êdz£Á¿£¬²»ÄÜÔÚ±àÒëÆÚ¾ÍÈ·¶¨£¬ËùÒÔnew String() ´´½¨µÄ×Ö·û´®²»·ÅÈë³£Á¿³ØÖУ¬ËüÃÇÓÐ×Ô¼ºµÄµØÖ·¿Õ¼ä¡£
¿´Àý2£º
String s0=”kvill”;
String s1=new String(”kvill”);
String s2=”kv” + new String(“ill”);
System.out.println( s0==s1 );
System.out.println( s0==s2 );
System.out.println( s1==s2 );
½á¹ûΪ£º
false
false
false
Àý2ÖÐs0»¹Êdz£Á¿³ØÖДkvill”µÄÓ¦Óã¬s1ÒòΪÎÞ·¨ÔÚ±àÒëÆÚÈ·¶¨£¬ËùÒÔÊÇÔËÐÐʱ´´½¨µÄжÔÏó”kvill”µÄÒýÓã¬s2ÒòΪÓкó°ë²¿·Önew String(“ill”)ËùÒÔÒ²ÎÞ·¨ÔÚ±àÒëÆÚÈ·¶¨£¬ËùÒÔÒ²ÊÇÒ»¸öд´½¨¶ÔÏó”kvill”µÄÓ¦ÓÃ;Ã÷°×ÁËÕâЩҲ¾ÍÖªµÀΪºÎµÃ³ö´Ë½á¹ûÁË¡£
4. String.intern()£º
ÔÙ²¹³ä½éÉÜÒ»µã£º´æÔÚÓÚ.classÎļþÖеij£Á¿³Ø£¬ÔÚÔËÐÐÆÚ±»JVM×°ÔØ£¬²¢ÇÒ¿ÉÒÔÀ©³ä¡£StringµÄintern()·½·¨¾ÍÊÇÀ©³ä³£Á¿³ØµÄÒ»¸


Ïà¹ØÎĵµ£º

Java NIO APIÏê½â

 
Java NIO APIÏê½â
ÔÚJDK
1.4ÒÔǰ£¬JavaµÄIO²Ù×÷¼¯ÖÐÔÚjava.ioÕâ¸ö°üÖУ¬ÊÇ»ùÓÚÁ÷µÄ×èÈû£¨blocking£©API¡£¶ÔÓÚ´ó¶àÊýÓ¦ÓÃÀ´Ëµ£¬ÕâÑùµÄAPIʹÓúܷ½
±ã£¬È»¶ø£¬Ò»Ð©¶ÔÐÔÄÜÒªÇó½Ï¸ßµÄÓ¦Óã¬ÓÈÆäÊÇ·þÎñ¶ËÓ¦Óã¬ÍùÍùÐèÒªÒ»¸ö¸üΪÓÐЧµÄ·½Ê½À´´¦ÀíIO¡£´ÓJDK 1.4Æð£¬NIO
API×÷Ϊһ¸ö»ùÓÚ»º³åÇø£¬²¢ÄÜÌṩ·Ç×èÈû(non-blo ......

java±ÊÊÔ

1.MVCµÄ¸÷¸ö²¿·Ö¶¼ÓÐÄÇЩ¼¼ÊõÀ´ÊµÏÖ?ÈçºÎʵÏÖ?
´ð£ºMVCÊÇModel£­View£­ControllerµÄ¼òд¡£"Model" ´ú±íµÄÊÇÓ¦ÓõÄÒµÎñÂß¼­£¨Í¨¹ýJavaBean£¬EJB×é¼þʵÏÖ£©£¬ "View" ÊÇÓ¦ÓõıíÊ¾Ãæ£¨ÓÉJSPÒ³Ãæ²úÉú£©£¬"Controller" ÊÇÌṩӦÓõĴ¦Àí¹ý³Ì¿ØÖÆ£¨Ò»°ãÊÇÒ»¸öServlet£©£¬Í¨¹ýÕâÖÖÉè¼ÆÄ£ÐͰÑÓ¦ÓÃÂß¼­£¬´¦Àí¹ý³ÌºÍÏÔʾÂß¼­·Ö³É²» ......

Java µ÷Óà Windows API ¿ÉÄÜÐÔµÄʵÏÖ

ÔÚ Google ÊäÈë java call win32api µÄµÚÒ»¸ö½á¹û
http://www.jinvoke.com/calling-the-win32-api-from-java
¾ÍÊÇÎÒÐèÒªµÄ´ð°¸¡£ºÇºÇ
¿´¿´Õâ¸ö°É
java°æÈÎÎñ¹ÜÀíÆ÷
java°æ×¢²á±í±à¼­Æ÷
Calling the Win32 API from Java
Ê×ÏÈ´Ó http://www.jinvoke.com/calling-the-win32-api-from-java ½« jinvokeÏÂÔØ»ØÀ´
½« ......

Java SE Static Inner

/*ÄÚ²¿ÀàʹÓÃʾÀý*/
package demo;
class Outer{
 int outer_i=100;
 static int outer_j=200;
 final int outer_k=300;
 void test(){
  Inner in = new Inner();
  in.display();
 }
 static class Inner{
  void display(){
    ......

javaÈÕÆÚת»»

/**
  * ´¦Àíʱ¼äÒì³£ Date to String
  * Èç¹ûת»»³öÏÖÒì³£»á¸øÄ¬ÈÏÖµ00:00
  * @param time
  * @param sdf
  * @return
  */
 public static  String handleDateParseException(Object time){
  String tempTime = "00:00";
  try{
   ......
© 2009 ej38.com All Rights Reserved. ¹ØÓÚE½¡ÍøÁªÏµÎÒÃÇ | Õ¾µãµØÍ¼ | ¸ÓICP±¸09004571ºÅ