fundamentals of electrodynamics

Linux System Fundamentals (ii)First, the Linux system structure1.Linux system structure is inverted tree type2./bin # #二进制可执行文件也就是系统命令/sbin # #系统管理命令存放位置/ Boot # #启动分区, responsible for system startup/ Dev # #设备管理文件/ etc # #大多数系统管理文件 /Home # #普通用户的家目录/lib # #32位系统库文件存放位置/lib64 # #64位系统库文件存放位置/media # #系统临时设备挂载点/mnt # #系统临时设备挂载点/run # #系统临时设备挂载点/opt # #第三方软件安装位置/proc # #系统信息/root # #超级用户家目录/srv,/var # #系统数据/sys # #系统管理, mostly about the kernel/ tmp # #系

Introduction: TitleImportJava.io.FileInputStream;ImportJava.io.FileOutputStream;/** * @authorCzchina **/ Public classTeststream { Public Static voidMain (string[] args) {FileInputStream FLs=NULL; FileOutputStream Fos=NULL; Try{FLS=NewFileInputStream ("E:/android/androidstudioprojects/text.txt"); FOS=NewFileOutputStream ("E:/android/androidstudioprojects/store.txt"); //generating a byte array byte[] buffer=New byte[500]; intnum = 0; intTMP = 0; intTMP1 = 0; for(inti=0;i) {tmp= Fls.rea

Introduction: Title ImportJava.io.FileInputStream;/** * @authorCzchina **/ Public classTeststream { Public Static voidMain (string[] args) {//TODO auto-generated Method Stub//declaring a reference to an input streamFileInputStream FLS =NULL; //declaring a reference to the output streamFileOutputStream fos =NULL; Try{ //first, generate an object representing the input streamFLS =NewFileInputStream ("E:/android/androidstudioprojects/text.txt"); //generating a byte array byte[

selector (Event- driven ) and the non-blocking feature of socket channel, it can effectively solve the situation that the high concurrency environment consumes a lot of thread resources for client request processing. (1) Traditional synchronous blocking IO (network socket programming socket): Each request for the client connection, need to allocate a separate thread for processing, because at any time to monitor whether it has data read and write, and in the data read and write operation, becau

Countdown shutdown command Tsshutdn ——-60-second Countdown shutdown command TOURSTART--XP profile (roaming XP programs that appear after installation is complete) taskmgr--– Task Manager EVENTVWR ——-Event Viewer Eudcedit ——-Character-font procedure Explorer ——-Open Resource Manager Packager ——-Object Wrapping Program perfmon.msc--Computer Performance Monitoring Program progman--– Program Manager regedit.exe--Registration Form Rsop.msc ——-Group Policy result set Regedt32

[One Moss per day]-Fundamentals of the Large Pool the following describes the 'large Pool 'introduced from Oracle 8 '. What is Large Pool ")? A large pool is an area in SGA similar to a shared pool, but its usage is strictly limited. Only a few types and sizes of memory can be allocated in this pool. The memory of the large pool is not from the shared pool, but directly from the SGA. Therefore, you need to increase the shared memory capacity when the

) { new Test02 (); T.test (); System.out.println (s);//Error }publicvoid Test () { System.out.println (s) ;}}unresolved compilation problem: static reference to the non-static field sIt is still reported that a static method cannot invoke a non-static variable.Although, the object of this class is initialized in a static method.The reason for the moment is unclear, Java, new an object and class static domain, is not in memory is not a place, have seen a video be

collections class cannot instantiate.Multithreading1, the difference between threads and processes4 states of a thread: run, ready, suspend, end.A process can have multiple threads, sharing the program's memory space between threads (code snippets, data, heap space, and some process-level resources, such as open files), but each thread has its own stack space.1) Use multithreading to reduce the response time of the program.2) threads are less expensive to create and switch than processes, makin

the upper layer into the packet segment to the lower layer. At the receiving end, the TCP protocol is responsible for reorganizing the received messages to the upper layer. The TCP protocol also handles end-to-end traffic control to avoid slow receivers not having enough buffers to receive large amounts of data sent by the sender. The UDP protocol is an unreliable, non-connected protocol .IP address: IP URL and IP host address. The IP URL represents the address of the network, and the IP host a

them in bulk and reclaim the memory at the right time (for example, by pressing the pause key or the level switch). Mono's memory recovery is done automatically in the background, and the system chooses the right time for garbage collection. At the right time, you can also manually call System.GC.Collect () to suggest that the system do a garbage collection.It is important to note that the call here is really just a suggestion, that the system may be recycled after a period of time, or it may b

; //newobj.i = this.i; //return NEWOBJ; //implementing Deep Replication-Mode 2: Serialization/deserializationBinaryFormatter BF =NewBinaryFormatter (); MemoryStream Ms=NewMemoryStream (); Bf. Serialize (MS, This); Ms. Position=0; returnBF. Deserialize (MS); } ...... } [Serializable] Public classA { Public stringMessage ="I am the original a"; }View Code PS: generally inheritable types should avoid implementing the ICloneable interface , because doing so would force a

1, b/s software system structure Network software system development including C/s and b/s two kinds of architecture, can carry out the same business processing. C/S is client/server abbreviation, both client and server structure, like commonly used QQ, and so on network software. b/S is brower/server abbreviation, both browser and server structure, only need to launch a browser. Our mobile applications are all part of the C/s structure. 2, the basic concept of network

system1) Resolve name conflict issues2) Easy class Managementfull-Limit naming of classes: Package name + class nameCp: Mount PathImport Imports date Gets the current time7.public source file can only have one Public common class name and file name consistent8.Javac Java source files compiled into a class file can compile multiple files at a time9.Java program starts from main method10.Java There can be more than one Java class in a source file . However, there can be only one Multiple sou

In a template-specific version of a call, the argument type must exactly match the formal parameter type of the special version function, and if it does not, the compiler instantiates an instance for the argument template definition. Lift a chestnut: Template Again, the argument type must be the formal parameter type of the special version function. Exact Match, even if there is no const in the front of the argument, and the template parameter does not constitute a special. The sp

message, int delay) {this.message = message;//Create a timertimer timer = new Timer (delay, new TimerListener ()); Timer.start ();} public void Paintcomponent (Graphics g) {super.paintcomponent (g); if (Xcoordinate > GetWidth ()) {xcoordinate =-20;} Xcoordinate + = 5;g.drawstring (message, xcoordinate, ycoordinate);} Class TimerListener implements ActionListener {/** Handle actionevent */public void actionperformed (ActionEvent e) {Repai NT ();}}}}Implementing messages moving through windows"

Manipulate the window to display the action steps in the consolePackage Chapter16;import Java.awt.event.windowevent;import Java.awt.event.windowlistener;import javax.swing.JFrame ; @SuppressWarnings ("Serial") public class Testwindowevent extends JFrame {public testwindowevent () {Addwindowlistener ( New WindowListener () {///anonymous inner class @overridepublic void windowopened (WindowEvent e) {System.out.println ("open");} @Overridepublic void Windowiconified (WindowEvent e) {System.out.prin

Readtcp () throws exception{ServerSocket Ss=null;InputStream Is=null;try {Ss=new ServerSocket (8080);Socket s1=ss.accept ();Is=s1.getinputstream ();byte [] b=new byte[10];int Len;while ((Len=is.read (b))!=-1) {String Str=new string (b, 0, Len);System.out.println (str);}} catch (IOException e) {TODO auto-generated Catch blockE.printstacktrace ();}finally{if (is!=null) {Is.close ();}if (ss!=null) {Ss.close ();}}}}------------------------------------------------------------------------------------

) { for(intj = 0; J ) {System.out.print (Data[i][j]+ " "); } System.out.println (""); } }}The results of the program run as follows:6. Using the stream to print an array, we can convert the array to a stream and print it out.code example: PackageCom.himi.printarray;Importjava.util.Arrays;/** Use stream to print an array * We can convert it to a stream and print it out. */ Public classStreamarray { Public Static voidMain (string[] args) {//Arraystring[] Arraystr =Newstring[]{"Java

12th. Graphical Interface Basics1. is that class the root of the Java GUI component? is the container Class A subclass of component? Which class is the root of the swing GUI build?Java.awt.component is the root of all Java GUI component classes.A container class, such as JFrame, is a subclass of a component.JComponent is the root of the Swing GUI component class.2.AWT components different from swing build?The components of AWT are heavy and swing components are lightweight.3.You can add a button

private, create static final class object in Class =new class (); ___ Singleton mode Inherit extends The default inherits the properties and methods of the parent class public, implicitly inheriting private, and prohibiting subclass access Method and property with the same name override, to subclass first Polymorphic Parent class object =new subclass instantiation (); Down transformation Subclass up to parent class (cast) Abstr