java coding best practices

Coding and decoding of two-dimensional code qrcode in Java Related to some of the main class library, convenient for everyone to download: Code Lib:Qrcode_swetake.jar (Website introduction-- http://www.swetake.com/qr/index-e.html) Decoding Lib:qrcode.jar (Website introduction-- http://sourceforge.jp/projects/qrcode/) "One", Code: Java Code Qrcodeencoderhandl

, int[] R3, int[] R4) throws illegalargumentexception{Ensure the arrays is of equal size......}9) ToString methodIn general, each class should define a ToString method:Public String toString () {...}) Main methodGeneral class, consider placing a main () method that contains the code used to test the class, and if it contains the main () method, it should be written at the bottom of the class.4. Java Coding

public key, the public key and the private key belong to the message passing parties, carries on the encrypted message passing.Consider a scenario.A machine module needs to export the data to a file, send the file to the B machine, and import the data by B.In this scenario, a is equivalent to the server, which needs to give the certificate to B, encrypt the data with the private key, generate the signature, and export to the file.b corresponds to the client, using the received digital certifica

recycled by GC because they are circular references to each other.2. Root Search algorithmA series of objects named "GC Roots" are used as starting points from which to search down, and when you reach objects that are not on the GC Roots reference chain, even if they are related to each other, they are still considered recyclable objects.Using the theory of graph theory, can be expressed as GC roots to the object unreachable .3. Better understanding of "references"In

Below are some of the practices circulating on the Internet to improve performance. I have made some comments on some of them: 1. Use the singleton whenever possibleThe use of Singleton can reduce the load burden, shorten the loading time, and improve the loading efficiency, but not all of them are applicable to singleton. Simply put, the Singleton is applicable to the following three scenarios:First, control resource usage and control concurrent

we call the second position, the encoding in the page encoding declaration should be the same as the encoding used when the Web page file was saved. and the browser's coding settings are actually not strict, as we said in the third section, in the browser choose to use GB2312 to view, it will actually still use GBK. And the browser also has the good habit, that it will try to guess what to use the code to see the most appropriate. I would like to r

. Since I have set the operation as a high-level concept, more work can be done freely at the underlying runtime. For imperative objects, developers often consider using reusable classes because their language encourages classes as building blocks. Function programming languages tend to reuse functions. Functional Languages construct complex general functions (suchfilter(),map()Andreduce()) And can be customized by functions provided as parameters. In functional languages, it is common to conver

The first part walks into Java one, into Java1. OverviewJava is widely used in embedded systems, mobile terminals, enterprise servers, mainframe and other occasions, to get rid of the constraints of the hardware platform, to achieve the "write once, run everywhere" ideal2. Java Technology Architecture　　According to the function to divideIncludes the following components:

member variable: Need to use GET, set method read, setting9.2. Important or repetitive expressions or methods should be extracted.9.2. Exception handling: Do not ignore any exception information. If you want to track more advanced exceptions, do not ignore the lower level exception information.9.3. Release resources: If you need to release resources, you need to put them in a finally block.Other references:Http://www.oracle.com/technetwork/java/codec

The norm needs to be noticed in the regular coding process, which is a good habit to develop slowly.1. Basic PrinciplesMandatory principle:1. The StringBuilder of the string must be used;The use of 2.try...catchTry {}catch{Exception e e.printstacktrace ();} finally {}// can be used in the outermost action, all other places are forbidden to use;Try { // program code }catch(Exception e) { // is empty, nothing is written } // prohibit use in any

directly allocated NIO buffer to read sensitive data from a file. After the data has been used. It can be cleared immediately, and sensitive data is not slow to exist in multiple locations, only in system memory.void ReadData () {Bytebuffer BB = bytebuffer.allocatedirect (16*1024); try (filechannel rdr = (new FileInputStream ("file")) . Getchannel ()) {while (Rdr.read (BB) > 0) {//does something with the Bufferbb.clear ();}} catch (Throwable e) {//Handle err or}}It is important to note that the

), which uses other encryption modes other than the ECB, needs to pass in an initial vector, which is equal to the block size and the AES block size is 128bit, so the length of the IV is 16 bytes and the initial vector can enhance the algorithm strength. Encryption Mode (Cipher mode) has CBC, ECB, CTR, ofb, CFB five species. The Padding method (Padding) determines the content that the last block needs to be populated, filled with pkcs5padding, pkcs7padding, nopadding three, but the JDK only prov

,sqlexception,timeoutexception, TooManyListenersException,TransformerException,TransformException, unmodifiableclassexception,unsupportedaudiofileexception,unsupportedcallbackexception, Unsupportedflavorexception,unsupportedlookandfeelexception,urireferenceexception,urisyntaxexception,userexception,xaexception,xmlparseexception, Xmlsignatureexception,xmlstreamexception,xpathexception 13. ReferencesAnders Hejlsberg on why not introduce Java -l

In fact, work so long has not been clear how to deal with the exception, by chance to see a foreign language feeling is good, then translated it down, the original link is located at the end of this article.Handling Exceptions in Java is not an easy thing to do, and not only do beginners find it difficult to understand that even experienced developers spend hours discussing whether an exception should be thrown or disposed of.That's why most developme

I. Coding and decoding involved in the Java Web We all know that for Chinese, where I/O is involved in coding, I have already mentioned I/O operations can cause coding, and most I/O generated garbled is network I/O, since almost all applications now involve network operations, and data is transmitted over the network i

before the question, let's take a look at what is Url,uri and QueryString, as shown in 1:Figure 1:url-uri-querystringURL: is the acronym for the Global Resource Locator, as above localhost: refers to domain (IP or hostname), 8080: is the port Web service is generally 80,8080 is the use of its own test, to avoid and browser port conflicts.ROOT: Is the Contentpath, which is the virtual path, if the Tomcat server object is the Servlet: Is the Servletpath message, which corresponds to the Getspecial

Java inside the built-in strings are all UTF-16 encoding, detailed coding way to see hereimport Java.nio.charset.charset;import java.util.arrays;import java.util.Map; Public classString2bytes { Public Static voidMain (string[] args) {String str="\u005bab Me"; Mapcharset.availablecharsets (); for(String charsetName:charsetMap.keySet ()) {System. out. println (CharsetName +":"+ Charsetmap.Get(CharsetName));

Whether you're a novice or a senior programmer, it's always a good thing to review the practice of exception handling, because it ensures that you and your team can handle it when you're having problems. Handling Exceptions in Java is not an easy thing to do. Beginners find handling anomalies difficult to understand, and even senior developers spend hours discussing whether throwing exceptions or exceptions should be thrown.That's why most development

Java multi-thread programming practices-general Linux technology-Linux programming and kernel information. The following is a detailed description. Java 5 adds a new class library concurrency set Java. util. concurrent, which provides a wide range of API multi-threaded programming for concurrent programs, making

%, the former is 100 times the latter, but it does use the same number of digits in the binary. Can do better, the method is variable length coding, the guiding principle is high frequency with a shorter number of digits encoded, low frequency with a longer digit code. Huffman coding algorithm is to deal with such problems. Huffman coded Java implementation The d