coding dojo java

%, 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

%, 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

Java Coding Style:1. Factory method should be stateless.State normally refers to the member variables of class. Stateless, more precisely, it means immutable.Factory was just to create objects, and one call should not affect anothers, if it was mutable, then the method call Mnight The chance to the States.And then it would affect other calls which is not supposed to happen.2.Restrict the access level of any

Recently in a project, the overall project is to deal with the database, take out data to be submitted to an interface through the HTTP protocol. The specific function is not much to say, just talk about the inside of a point--coding problems In the project, it involves taking the MD5 value of all the data. In Java projects, individuals prefer to change the project's default encoding to UTF-8. The develop

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

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

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

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

"); System.out.println (Sunicode);//6, GBK encoded string SGBK = new String (BYTESGBK, "GBK"); System.out.println (SGBK);//If the restore by other encoding, there is garbled//1, UTF-16 encoding decoding UTF8 generated bytes string Sutf16erro = new String (Bytesdefault, "UTF16"); System.out.println (Sutf16erro);//2, decoding UTF8 bytes generated with unicode encoding string sunicodeerror = new String (Bytesdefault, "Unicode"); System.out.println (sunicodeerror);//3, decoding UTF8 generated bytes

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));

subscript of each node of the Huffcode array is filled by the back forward and the prefix of the encoding is guaranteed to be the same as XX ... huffcode[0][6]=1 huffcode[0][5]=0Then Huffcode is 0000 0001 that is small Mark 1 of a Huffman node Huffman slowedFor (Huffmannode c=hn[j],p=c.getparent ();p!=null;c=p,p=p.getparent ()) {if (P.getlchild (). Equals (c)) huffcode[j][start--]=0;else huffcode[j][start--]=1;}//a path to the same node.huffcode[j][start--]=-1;//to the remaining path is padding

meaning of the Description field */Special NOTES:TodoA place that has not been completed but must be completedFixmeWhere the bug must be modifiedIf a method is an implementation of an interface, then the detailed method document comment should be written in the method of the interface class, and the implementing class method should guide the past through the @see.Code optimization:1. Avoiding the "God class"2. Try to separate some logic implementations, especially reusable ones, into different

1, the class name uses the Hump name method, the first letter capitalization.2, the class variable uses the Hump name method, the first letter lowercase.3, the method name is a verb phrase, the first letter lowercase, as far as possible to describe the intent of this method.4, note in the fine not many, a good note to try to describe the code to express the meaning.5, a function of the different operations of the Code section separated by a blank line, convenient for later maintenance.6, the var

Package (packages)Naming conventions for package names: 1, lowercase 2, at least one level of directory 3, domain inversion writingPackage Baidu;Package com.baidu.www;Class (classes)----- Large Hump MethodNaming conventions for class names: capitalize all words in the first letterClass MobileClass TestmobileInterface (interface)Naming conventions for interfaces: Capitalize all words in the first letterInterface Animal;Method (Methods)Naming conventions for methods: first letter lowercase, initia