head first core java

Source of information: Software talent net Author: bristling super2002 I wrote an article on the Java implementation of the mail sent, when I wrote the message to send the function is very simple, can not bring attachments, can not have template. Later, a lot of friends asked me, there is no more perfect version, the existing mail sent me to write the design idea is convenient to send the attachment, you can send HTML pages including built-in pictures

Lambda An expressionform: parameter, arrow (-), expressionParameter type to write, if you can deduce it can not writeOnly one argument can omit parenthesesNo arguments to write empty brackets ()* If the branch returns a value, then all branches will return a value, otherwise it is illegalfunction interface: interface with only one abstract method (can be marked with @functionalinterface annotations)For example, you can do this in Javax.swing.Timer.　　　　　　Timer T = new timer (+, event-{...});The s

For this code, a lot of netizens are full of questions, first there are many, not careful, did not write the pair class, to compile.Certainly compiled, the pair class is on the first two pages of the other code.And here, the features of generics are written. By several constructors, and the change of parameters, the generic type is explained.Package pair1;public class pairPrivate T first;Private T second;Public Pair () {first = null;second = null;}Public Pair (t first, t second) {This.first = Fi

Why is the use of volatile lower than the cost of synchronization? The cost of synchronization is mainly determined by its coverage, and if you can reduce the coverage of synchronization, you can significantly improve program performance. And volatile's coverage is variable-level only. Therefore, its synchronization cost is very low. What is the volatile principle? Volatile's semantics, in fact, is to tell the processor, do not put me into working memory, please directly in main memory opera

schematic, the inside of the compiler is certainly not outer An implicit reference to an external class is set in the constructor. The compiler modifies all constructors for the inner class, adding a parameter that references the external class. Even if you do not define a constructor for an inner class, the compiler generates a default constructor for the inner class. such as:Publictimeprinter (talkingclock clock) {outer = clock;}When an inner class object is created in the Start method, th

1. ExceptionsThe user wants the program to take some sensible action in the event of an error. If some operations cannot be completed due to an error, the program should: return to a security state and be able to make some other commands, or allow the results of all operations to be saved and terminate the program in an appropriate manner.Exception handling tasks: Transfer control from where the error occurred to an error handler that can handle the situation.Exception Categories: Throwable:erro

The book is generally finished, but the seventh chapter is not in a hurry to end.But fortunately it is finished, barely count it.Recall this year, quite feeling, the heart has been seeking progress, but it is very difficult to act up.Think about it indeed ah, want to always progress must sacrifice their spare time, although not to exclude learning, but you have to admit that the feeling of paralysis is very good.Man, there's really nothing to stop, and once you get down, you're probably going to

JSTL Core Tag Library has a total of 13 tags, functionally divided into 4 categories: 1. Expression control Tags: out, set, remove, catch 2. Process Control Tag: If, choose, when, otherwise 3. Cyclic Tags: forEach, fortokens 4.URL operation tag: import, URL, redirect When using labels, be sure to include the following code in the header of the JSP file: These labels are described in the following sections: 1.

; } Private Statictarget) {T ret= (T) proxy.newproxyinstance (qrpcfactory.class. getClassLoader (),NewClass[] {target, irpccontext.class},NewInvocationhandler () {Qmodel Modelanno= Target.getannotation (Qmodel.class); Private ShortModel =Modelanno.value (); PrivateRpccontext CTX; @Override PublicObject Invoke (Object proxy, Method method, object[] args)throwsThrowable {if(Method.getname (). Equals ("SetContext")) { This. CTX = (rpccontext) args[0]; System.out.println ("SetContext

It can be mixed, without conflict. Ehcacheall the Cache interfaces are implemented. Ehcache . Each cache has a name and attributes, and contains Element. Ehcache in the Cache equivalent to a piece of cache area in another cache system. ElementElement is stored in Cache the atomic units in the. It has a key, a value , and a record of access. Element is either placed in the cache or removed from the cache . They may also be removed due to expiration, which relies on configuration. References:Sou

The core of the future model is the removal of the wait time for the main function and the time period that would otherwise have to wait for processing other business logic (according to Java Program Performance optimization).The future mode is somewhat similar to a commodity order. When you shop online, after you submit your order, you don't have to wait at home at the time of receipt to do something else.

This paper briefly introduces the core application of JCE framework. Javax.crypto.Cipher This class provides password functionality for encryption and decryption. It forms the core of the Java cryptographic Extension (JCE) framework. To create the Cipher object, the application invokes the Cipher getInstance method and passes the name of the requested transformat

when serializing.5) class used for serialization of objects: ObjectOutputStreamWriteObject (Object obj): ① serializes the given object. ② then writes.6) The class used by the deserialization of the object: ObjectInputStreamObject ReadObject (): Restores the read sequence of bytes to an object Case Study:650) this.width=650; "title=" Clipboard-28.png "src=" http://s3.51cto.com/wyfs02/M02/71/1C/ Wkiom1xfz9tyhdsfaanxrtvuejw190.jpg "alt=" Wkiom1xfz9tyhdsfaanxrtvuejw190.jpg "/>650) this.width=

List 13.1 Linklist/linkedlisttest.javaLinklist of Java ContainersPackage Linklist;import Java.util.linkedlist;import Java.util.list;import Java.util.listiterator;public class Linklisttest{public static void Main (String args[]) {list Copyright NOTICE: This article for Bo Master original article, without Bo Master permission not reproduced. Java Core Technology Vo

routine to review the concepts that we have described earlierPackage pair3; Public classpairtest3{ Public Static void Main(string[] args) {Manager CEO =NewManager ("Gus greedy.",800000,2003, A, the); Manager CFO =NewManager ("Sid Sneaky",600000,2003, A, the); PairNewPair1000000); Cfo.setbonus (500000); Manager[] Managers = {CEO, CFO}; pairNewPair out. println ("First:"+ Result.getfirst (). GetName () +", Second:"+ Result.getsecond (). GetName ()); Maxminbonus (managers, result); Syste

Next how to ImplementFirst step: First, the service class, call method to convert to digital, easy to transferThe second step: Extract meta-information, extraction and three ways, three kinds have advantages, the best way is the first1. Processing when compiling Java2. Program start-up processing, preprocessing3. Call processing, lazy processingStep Three: Encoding interpretationFourth Step: Request methodFifth Step: Distributed supportThe first step:@Target (Elementtype.type) @Retention (retent

=str.tostring ();8 System.out.println ("After insertion:" +STR2);Output Result: 12Hello world!After insertion: Hello world!!Note : StringBuffer and StringBuilder function the same, but StringBuffer is thread-safe, and StringBuilder does not implement thread-safe functionality, so performance is slightly higher. Therefore, in general, if you need to create a variable-content string object, you should consider using the StringBuilder class as a priority.Second,"= =" and equals () What is the diffe

constructor with reflection----> Create ObjectPackage classinstance;//uses reflection to call the constructor--Create object import java.lang.reflect.constructor;class Peson {public Peson () { System.out.println ("parameterless constructor");} Public Peson (String name) {System.out.println ("parameterized constructor" + name);} Private Peson (String name, int age) {System.out.println ("parameterized constructor" + name + "," + Age);}} public class Cteateobject {public static void main (string[]

);7 });8 }9 Ten @Test One Public voidTestFilter1 () { APackagescanner.scan ((CLZ) { - System.out.println (CLZ); -}, "Com.eyu.onequeue"); the } - - @Test - Public voidTestfilter () { +setNewHashset(); -Packagescanner.scan ((CLZ) { +Qmodel Modelanno = Reflectutil.getanno (CLZ, Qmodel.class); A if(Modelanno = =NULL) { at return; - } - Values.add (CLZ); -}, "Com.eyu.onequeue"); - for(classclz:values) { - if(Clz.i

File action Filter (FilenameFilter):Listfiles (FilenameFilter filter) Method:The actual equivalent is://File filter (FilenameFilter)Public class FileDemo1 {Public static void Main (string[] args) {file dir = new file ("C:/users/37335/desktop/java application Framework");file[] fs = Dir.listfiles (new FilenameFilter () {//File filter interface, dir file path, name of file@OverridePublic Boolean Accept (File dir, String name) {//If the file exists and t