core java volume

If you want to know a general knowledge of multithreading, you can look at this article first.Changes in each state of the thread.Look at wait.Import java.util.concurrent.arrayblockingqueue;/** * Producer-Consumer * * @author Zzs. * @since 2018/3/24 */public class Blockingqueuetest {private int size = 20; Private arrayblockingqueue　　Java Core Technology point of multi-threading 2

Well known in. NET, the key generated by the RSA class is in XML format, while other languages such as Java generally use the PKCS8 format key, JavaScript generally uses the PKCS1 format. We in the development process is likely to encounter the need to interface with other languages developed API, if we encounter RSA encryption and decryption, we must ensure that key is the same, in order to ensure the correct processing of data, we definitely need to

Java naming convention: The first letter lowercase, the first letter of the following word, the camel's name.Be aware of the label:typealiases> in the label properties> below.Four, mapper mapper :1) Resource way:1 "account.xml" />2) class mode:1 class="jd.com.proxydao.AccMapper" />Specification Requirements:1:mapper files and interfaces need to be under the same package.The name of the 2:mapper mapping file needs to be the same as the name of the int

API for the JDBC interface core@author IxenosJava.sql.* and Javax.sql.*|-Driver Interface: Represents the Java driver interface. All of the specific database vendors are going to implement this interface.|-Connect (URL, properties): A way to connect to a database. URL: The URL of the connection database URL syntax: JDBC Protocol: Database Sub-protocol://HOST: Port/Database User: Username fo

asvalues = Size.values();Returns an array containing the element size.small,size.medium,,size.extra_large.(4) The Ordinal method but the position of the enum constant in the enum declaration, where the position is counted from zero, for example Size.MEDIUM.ordinal () returns 1.7. Techniques for succession design(1) Placing public operations and domains in super-class(2) do not use protected domainsThis is because, first, the collection of subclasses is unrestricted, and any one can derive a sub

, the algorithm converts each character using 1-4-byte encoding.Code point/code unit (JDK 5.0) A code point is a code value (Unicode encoding) that corresponds to a character in an encoded table.In Java, the char type describes a code unit with UTF-16 encoding.UTF-16 uses a different length of encoding to represent all Unicode code points . In the basic multilingual plane, each character is represented by 16 bits (often referred to as a unit of

A termJdk:java delelpment JitJre:java Runtime EnvironmentSecond, installation jdk1.8.0_25Setting environment variables (recommended to be installed directly under C-drive), using;C: \java\jre1.8.0_25\bin;Third, unzip the source file methodEnter C: \java\jre1.8.0_25Create SRC subdirectorymkdir SRCCdsrcUnzip the fileJar XVF. \src.zipI. Using command-line toolsJava Helloworld.java with

child class is placed in the parent class object, and only methods of the parent class can be called. 1 Employee empl = new Manager () 2 Empl.setbonus (100); // compile error, no Setbonus method in parent class 3 4 // You can convert a parent class reference to a subclass reference 5 if (empl instanceof Manager) { Span style= "color: #008080;" >6 Manager Mgr = (manager) Empl; 7 Mgr.setbonus (100 8 } When a method is declared final, the subclass cannot overwrite it. Final does

Java core programming-IO stream Overview (-), javaio 1. Four most critical parent classes of java io streams ~ InputStream (input byte stream) ~ OutputStream (output byte stream) ~ Reader (input stream) ~ Writer (output streams) All the above four classes are public abstract class classes. InputStream and OutputStream are transmitted in byte (byte. Reader

pointer exception when the value is unboxing if the key does not exist get returns nullint count = Counts.getordefault ("A", 0);//Recommended UseThe counter, when present, adds one:Counts.merge (Word, 1, integer::sum);If the word key does not exist before, connect Word with 1, or use the Integer::sum function to add 1 to the previous valueP243 Map Method! I didn't read it.1 // Iteration Map 2 for (map.entry entry:counts.entrySet ()) {3 String k = entry.getkey (); 4 Integer V = entry.getval

The theoretical knowledge is boring, but these are basic skills and may be forgotten after learning. However, when used, we will find that the previous learning is very meaningful, and the learning thread is like this. 1. how to Create a lock? Lock lock = new ReentrantLock (); 2. How to Use the Lock? See the Lock document. The format is as follows: class X {private final ReentrantLock lock = new ReentrantLock ();//... public void m () {lock. lock (); // block until condition holds try {//... met

In Java, every variable, constant is a type.variables :Example: int i;Double A;1 The variable name must be a sequence of alphanumeric characters beginning with a letter. But unlike most programming languages, the range of letters and numbers in Java is larger, and the letters include ' a ' ~ ' Z ', ' a ' ~ ' Z ', ' _ ' or any Unicode character that represents a letter in any language, such as Chinese: decla

. String---> Byte streamCombines the functions of both bufferedwriter/outputstreamwriter2. can automatically refreshNew PrintWriter (os,true);UDP User Data Message Protocol-------------------------------------------1) Consider the efficiency of data transmission, reliability is not guaranteed2) Not necessarily a one-to-many communication, such as broadcasting3) non-connected, unreliable transmission modeDatagramsocket responsible for sending and receiving data such as the PostmanDatagrampacket d

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

; } 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=