java coding practice

Java Drp project practice-ServletOrigin Before explaining the Servlet, we need to first introduce a word CGI, that is, the Common GatewayInterface is the meaning of a universal gateway interface, which provides an interface for a computer program with the HTTP protocol or WWW Service, that is, the meaning of the human-computer interaction interface. When a Web application runs on a server and a client req

conversion of binary and decimal.NThe binary can be understood as: numericalxThe power of a base, such as the decimal number we are familiar with123.4=1x10²+2x10+3x (Tenof the0Second Power) +4x (Tenof the-1Second Power)the same is true of other binaries, such as binary numbers11.01=1x2+1x (2of the0Second Power) +0+1x (2of the-2Second Power)=of decimal3.The child's powder forging, the crazy fist -. Doublethe value of the type occupies64bit, i.e. -Binary number, except that the highest bit repres

Java Theory and Practice:Concurrent collection classConcurrenthashmap and copyonwritearraylist provide thread security and improved scalability. Document options Valign = "TOP"> Width = "122">

Java Theory and Practice: Use Weak references to block memory leaks-Linux general technology-Linux programming and kernel information. The following is a detailed description. Although Java™In theory, a program written in a language does not have a "memory leak", but sometimes objects are not garbage collected after they are no longer part of the logic state of t

Java Open Source Practice 1--environment Configuration Wuder The software required for deploy under Window System: The following software is executed under window Jdk5.0 Download Address: http://java.sun.com/j2se/1.5.0/download.jsp Jdk-1_5_0_01-windows-i586-p.exe Jboss4.01 Download Address: http://prdownloads.sourceforge.net/jboss/ Jboss-4.0.1sp11.zip Mysql4.1 Download Address: http://dev.mysql.c

Snap to it and then how to deal with it?Many Java™ language methods, such as Thread.sleep() and Object.wait() , can be thrown InterruptedException . You cannot ignore this exception because it is a check exception (checked exception). But what should be done about it? In Java theory and practice this month, the concurrency expert Brian Goetz will explain Interrup

A+b for Input-output Practice (III)Time limit:2000/1000 MS (java/others) Memory limit:65536/32768 K (java/others)Total submission (s): 113961 Accepted Submission (s): 60127Problem Descriptionyour task is to Calculate A + B.Inputinput contains multiple test cases. Each test case contains a pair of integers a and B, one pair of integers per line. A test case contai

. volatilevariables are not cached in registers or in places that are not visible to other processors, so the volatile most recently written value is always returned when a variable of type is read.volatileYou should use variables only if they simplify the implementation of your code and validate your synchronization policies. If you need to make complex judgments about visibility when validating correctness, do not use volatile variables. volatilethe correct use of variables includes:

consumption only once, the same partition will only bind one consumer information.5, if a consumer hangs, consumer and partition binding information will be reassigned, as far as possible to ensure load balance6, if the number of consumer is greater than the number of partitions, will cause the redundant part of the thread can not get the message, constantly Got ping response for sessionid:0x153413bc26e0082 after 2ms. is a waste of resourcesIf more than one server starts the consumer process, i

Java improvements-understanding the application of String and String. intern () In practice, stringintern 1. First, String does not belong to eight basic data types. String is an object.Because the default value of an object is null, the default value of String is also null, but it is a special object and has some features that other objects do not have.2. Both new String () and new String ("") declare a ne

be recognized by the Computer. In fact, floating-point numbers are not suitable for precise calculations and are suitable for scientific calculations. float and double are used to denote numbers with a decimal point, and these numbers are stored in the form of scientific notation. When a number such as 50.534, converted to scientific notation in the form of 5.053e1, its decimal point moved to a new position (that is, Floating) visible, floating point is used for scientific calculation, for accu

" 0000 system.out.println (integer.tohexstring ( -128)); //ffffff80 //(-128 0xFF) Complement: 1111 1111 1111 1111 1111 1111" 0000 0000 0000 0000 0000 0000 0000 1111 1111 = 0000 0000 0000 0000 0000 0000" 0000 system.out.println (integer.tohexstring ( -128 0xFF)); //00000080 //byte byte_128 = (byte) -128 (---128 complement reserved last 8--0000) //byte_128 complement: 0000 //byte_128:1111 1111 (symbol bit invariant remaining bit reversed) //byte_128

The 1th part of this short series describes how to test effectively, building the FindBugs plug-in to find a simple bug pattern (just call System.GC ()). Bug patterns identify problematic coding practices that are often located in the area where the bug is located. Of course, not all bug patterns are necessarily bugs, but that doesn't negate the huge impact of bug pattern detectors. The main function of a valid bug pattern detector is to discover a hi

Recently made a technical blog site, organized a study of the Java process to do examples and small projects, are placed on the site to provide download, there are examples of beginners, there are Java Web examples, as well as my university during the graduation design source, can be downloaded.Address: micro-Child blog-java Novice

Many Java™ language methods, such as Thread.sleep() and Object.wait() , can be thrown InterruptedException . You cannot ignore this exception because it is a check exception (checked exception). But what should be done about it? In Java theory and practice this month, the concurrency expert Brian Goetz will explain Interruptedexception's meaning, why it throws in

Final keywords are often misused-they are used excessively when declaring classes and methods, but are not used enough when declaring instance fields. This month, Java practitioner Brian Goetz explored some useful final. Like in its cousin-CconstThe same keyword, according to the context,finalIt indicates different things.finalKeywords can be applied to classes, methods, or fields. When applied to a class, it means that the class can no longer genera

The new lock class improves synchronicity--but it can't be abandoned right now. SynchronizedJDK 5.0 provides a number of new and effective options for developers to develop high-performance concurrent applications. For example, a java.util.concurrent.lock class in the ReentrantLock Java language is synchronized replaced with the same memory semantics, the same lock, but with better performance under race conditions, and there are synchronized other fe

, removes the last element from the container in the method body and joins the consumer. Examples of use are: carcontainerIf you have another setThe method Pop (setOur idea is that the pop receives the parameter application is "E of some kind of superclass set", through the "and Super keyword combined use just can achieve this purpose, namely setThird edition public void pop (setAfter the modification, setWith the use of the extends or Super keyword on the method parameters, you get th

(); }/** * * */PublicvoidSendfinish () {sendfinish =True; }/** * * */PublicvoidRelease () {System.Out.println ("release!");if (BW! =Null) {Try{Bw.close ();}Catch(IOException e) {//TODO Print log.} }//In fact, using queue = null is enough.if (Queue! =Null) {queue.clear (); queue =Null; } }/** * * */PublicvoidSendmsg (String text) {if (Text! =Null !Text.isempty ()) {queue.add (text);}}PublicStaticvoidMain (string[] args) {Countdownlatch latch =New Countdownlatch (1); Asynchandler handler =NewAsyn

Apriori condition (precondition): Some methods contain a priori condition based on a state. For example, you cannot remove an element from an empty queue, and the queue must be in a non-empty state before the element is deleted. The operation of a state-based priori condition becomes a dependent state operation. In a single thread, if an operation fails to meet a priori condition, it can only fail, but in a concurrent program a priori condition may become true due to an operation performed b