teach kids java playful introduction to programming

values, both the read and write operations must use the same lock object.2. Not sharing status(1) Stateless objects: Stateless objects must be thread-safe because they do not affect other threads.(2) thread shutdown: Used only in single-threaded environments.3. Immutable objectsYou can use the final decorated object to ensure thread safety, because the final decorated reference variable (except string) is immutable because the reference is immutable, but the object it points to is mutable, so t

Introduction to Object Reading comprehension:1. The complexity of solving the problem directly depends on the type and quality of abstraction (abstract type and what is abstract?). ）。Assembly language is a slight abstraction of the underlying machine, while the C, basic, and other instruction-type languages are abstractions of assembly-language, and the main abstractions they do still require solving problemsTo be considered based on the structure of

-load-use and assign-store-write became two indivisible atomic operations.Although there is still a vacuum between use and assign, it is possible that the variables will be read by other threads, but the values of the main memory variables and any working memory variables are equal at any point in time. This feature causes the volatile variable to be unsuitable for operations that depend on the current value, such as self-increment.So depending on the visibility of the characteristics of volatil

For more than a year Java, Wild path origin, found that the Java Foundation this piece is still quite weak! So decided to learn the Java programming idea of the book. Here to learn the knowledge points recorded!Five characteristics of object-oriented1. All things are objects2. Programs are collections of objects that t

programprivate final int output_stop=4; Close the output stream, and then end the programPublic Sender () throws ioexception{Socket=new Socket (Host,port);}public static void Main (String args[]) throws exception{if (args.length>0) Stopway=integer.parseint (Args[0]);New Sender (). Send ();}Private PrintWriter getwriter (socket socket) throws ioexception{OutputStream socketout = Socket.getoutputstream ();return new PrintWriter (socketout,true);}public void Send () throws Exception {PrintWriter p

Import java.io.*;public class Echoplayer {public string Echo (String msg) {Return "Echo:" +MSG;}public void Talk () throws IOException {BufferedReader br=new BufferedReader (New InputStreamReader (system.in));String Msg=null;while ((Msg=br.readline ())!=null) {System.out.println (Echo (msg));if (Msg.equals ("Bye"))//When the user enters "Bye", End the programBreak}}public static void Main (String arg[]) throws ioexception{New Echoplayer (). talk ();}}Chapter One

;" +str);Pw.println (str); After sending the STR string, "\ r \ n" is also sent.}String response;If ((response = br.readline ()) = Null)System.out.println ("server>" +response);}Private PrintWriter getwriter (socket Socket) throws ioexception{OutputStream socketout = Socket.getoutputstream ();return new PrintWriter (socketout,true);}Private BufferedReader Getreader (socket Socket) throws ioexception{InputStream Socketin = Socket.getinputstream ();return new BufferedReader (new InputStreamReader

((Forkjoinworkthread) thread.currentthread). Puttask (this);}2) Puttask the current task into the task array and then calls Forkjoinpool's signalwork to wake up or create a new threadThe pseudo code is as followsPublic final void Pushtask (ForkjointaskForkjointask if (q=queue)!=null) {Calculate the offsetLong U = ((s=queuetop) (m=queuetop.length-1)) Flush main memory directly based on offsetUnsafe.putorderobject (q,u,t);queuetop=s+1;if (s-=queuebaseWaking worker ThreadsSignalwork ();}else{Creat

client{public static void Main (string[] args) throws Exception {Socket socket = new socket ("localhost", 9999);Sending information to the serverOutputStream OS = Socket.getoutputstream ();PrintStream PS = new PrintStream (OS);PS.PRINTLN ("Client-side services");Read the information sent by the serverInputStream is = Socket.getinputstream ();BufferedReader br = new BufferedReader (new InputStreamReader (IS));String str = br.readline ();System.out.println (str);Br.close ();Is.close ();Socket.clo

First, the object-oriented five basic features:1. All things are objects. treats an object as a peculiar variable, he can store the data, and can require it to perform operations on itself.2. A program is a collection of objects that they tell each other to do by sending a message.3. Each object has its own storage that is composed of other objects. in other words, you can create a new type of object by creating a package that contains an existing object.4. No object has its type. The most impor

Java Summary Common code: Scanner in = new Scanner (system.in); Usage of shortcut keys Note: Crtl +/ Fast input: Alt +/Mac:option +/ Select line of code: SHIFT + up/down arrows First, floating point numberSecond, priorityIii. type Conversion1.1 Floating-point numbers-this does not fully display, the floating-point number conflicts with Int.Solution: 12 instead of 12.0 Modify in

not depend on it. As a simple example: if you create a daemon thread in the main thread, when the main method finishes running, the daemon thread will die as well. The user thread does not, and the user thread runs until it finishes running. In the JVM, a garbage collector thread is the daemon thread.The thread class has a more commonly used static method, CurrentThread (), to get the current thread.The most of the methods in the thread class have been mentioned above, so how does a method call

example: The purpose is to put the elephant into the refrigerator, objects have, elephants and refrigerators, elephants to put in the refrigerator, need to put the refrigerator before the notice, open the door, the elephant in, notify the refrigerator, close the door.Three: Each object has its own storage that is composed of other objects. This is not discussed first.Four: Each object has its type. An object is an instance of a class, such as: An elephant is a class, but not a specific thing, t

This is my note on the Java course of learning web. The original video link is: http://www.imooc.com/learn/855-1 Basic NotationSelf-complementary shortcut keys: ALT +/5-2 input and outputUse the Scanner tool class to get user-entered score informationThe scanner class is located in the Java.util package and needs to be imported when using the packagesteps:1. Import Java.util.Scanner2. Create a Scanner object3. Receive and save user-entered valuesdiffe

improve the user experience of graphical software and prevent the "freezing" phenomenon from arising.Risk of threading:The first risk is that the execution sequence cannot be determined under multithreading, and there is an unexpected situation. Using the Java synchronization mechanism can improve the problem.The second risk is the case where a deadlock, such as a program, cannot continue.The third risk is that in multi-threading, thread scheduling a

Import java.net.*;Import java.io.*;public class HTTPClient {String host= "www.baidu.com";int port=80;Socket socket;public void Createsocket () throws exception{Socket=new Socket ("www.baidu.com", 80);}public void Communicate () throws exception{SYSTEM.OUT.PRINTLN ("---");StringBuffer sb=new stringbuffer ("GET" + "/" + "http/1.1\r\n");Sb.append ("host:www.baidu.com\r\n");Sb.append ("Accept: */*\r\n");Sb.append ("accept-language:zh-cn\r\n");Sb.append ("Accept-encoding:gzip, deflate\r\n");Sb.append

Import java.io.*;Import java.net.*;public class Simpleserver {public static void Main (String args[]) throws Exception {ServerSocket serversocket = new ServerSocket (8000,2); The length of the connection request queue is 2Thread.Sleep (360000); Sleep 6 minutes}}Import java.io.*;Import java.net.*;public class SimpleClient {public static void Main (String args[]) throws Exception {Socket S1 = new socket ("localhost", 8000);SYSTEM.OUT.PRINTLN ("First connection success");Socket s2 = new socket ("lo

Prime A Prime is an integer greater than one whose only positive divisors is one and itself.The prime factor decomposition of an integer is a collection of the product equal to this prime number.Example: 3757208 = 2*2*2*7*13*13*397 Public classfactors{ Public Static voidMain (string[] args) {//Print The prime factors of N. LongN = Long.parselong (args[0]); Longn =N; for(Longi = 2; I ) { //Cast out and print I factors while(n% i = = 0) {n/=i; System.out.print (i+ " ");

Public classbinary{ Public Static voidMain (string[] args) {//Print binary representation of N. intN = Integer.parseint (args[0]); intv = 1; while(v ) v=v; //Now V is the largest power of 2 intn = n;//Current Excess while(V > 0) { //Cast out the power of 2 in decreasing order. if(N ); } Else{System.out.print (1); n-=v;} V= V/2; } System.out.println (); }}Prints a binary representation of a 10-decimal number. Splits a number into the sum of

Swing was a GUI framework developed by Sun, and at the outset sun was developing the AWT framework. However, the AWT framework has LCD problems. As a result, Sun continued to develop swing on the basis of AWT. Swing is a class that inherits the AWT common components: Text text component Menus menu component Widgets Widget component Top-level-windows Top-level window Management sub-windows child windowOne of the Java GUI