fundamentals of electrodynamics

1. Can a button trigger the windowevent? Can a button trigger MouseEvent? Can a button trigger ActionEvent?JButton can produce mouseevent and ActionEvent. Cannot trigger WindowEvent2. Can a single source have multiple listeners? Can a listener have multiple sources? Can a listener make its own listener?YES. YES. YES3. Can internal classes be used in other classes that are not nested in him?Objects of an inner class is often created in the outer class. But the can also create an object of a inner

request. HTTP is text-oriented, so each field in the message is a number of ASCII strings, so the length of each field is indeterminate. There are two types of HTTP messages in total, requesting messages and responding messages.1) Request message2) Response message Both the request message and the response message can be divided into three parts.1) Start line2) Header LineMy habit is to call the two parts above, the message header. The following section is called the newspaper style

1. Class loadingBootstrap ClassLoader-Boot (also known as primitive) class loader, which is responsible for loading Java's core classes. Extension ClassLoader-the extension classloader, which is responsible for loading the class pack of the jar in the JRE's extended directory (Java_home/jre/lib/ext or specified by the Java.ext.dirs system properties). System ClassLoader-Systems (also known as applications) ClassLoader, which is responsible for loading-classpath or Java.class.path System Properti

1, how to get the current working directory?String path=system.getproperty ("User.dir");2. What is the difference between string x = "abc" and string x = new String ("abc")?String x= "abc"; the x variable points to a string object in the data segmentstring x = new String ("ABC") points to a string object in the heap, which must be copied into the object using a string in the data segment as a template;3. What is the difference between string and StringBuffer?String Immutable property, when we ch

This is only a brief description of TCP sockets, let us first look at how to write a simple server, here first with Linux C to achieve. Time . h > int main (int argc, char** argv) { int listenfd, CONNFD; Socketlen_t Len; struct sockaddr_in servaddr, cliaddr; Char Buff[maxline]; time_t ticks; LISTENFD = Socket (af_inet, sock_stream, 0); Bzero (servaddr, (SA *)servaddr, sizeof (SERVADDR)); Listen (LISTENFD, Listenq); for (;;) { len = sizeof (CLIADDR);

operations, using for-in, for, while, and do-while for looping. Wrapping conditions and loop variable parentheses can be omitted, but curly braces on the body of the statement are required.(6.1) for in control flowLet Indivadulscore = [70,66,80,90,56,34]var score = 0For S in Indivadulscore{If s>60{Score + = 20}else{Score + = 100}}Note: Look at the differences in the syntax of the control flow you wrote earlier(6.2)? indicates an optionalvar optionstring:string? = "Hello,world"Optionstring = = N

the callback function.Interface Intcompare{public Boolean cmp (int x,int y);} Class CMP1 implements Intcompare{public boolean cmp (int x,int y) {if (x > Y) {return true;} Else{return false;}}} Class CMP2 implements Intcompare{public boolean cmp (int x,int y) {if (x > Y) {return false;} Else{return true;}}} public class selectsort_s {public static void Selectsort (int[] A, intcompare cmp) {for (int i = 0; i The above example defines an interface intcompare that is used to compare size, whic

to let the waiting person wake up **/classStudentextendsThread {Private intscore; @Override Public synchronized voidrun () {Try{System.out.println ( This. GetName () + "Start exam ..."); Thread.Sleep (3000); System.out.println ("The exam is over and the quiz begins."); Thread.Sleep (3000); Score= (int) (Math.random () * 101); System.out.println ("The quiz is over, you can check your grades now."); This. Notify (); } Catch(interruptedexception e) {//TODO auto-generated Catch blockE.printstacktr

provided by a server.A port number is a place of access to a service that distinguishes multiple services on the same physical computer.Sockets are used to connect the client and server, and each communication session between the client and the server uses a different socket.The TCP protocol is used to implement a connection-oriented session. The network-related features in Java are defined in the java.net package.Java uses the InetAddress object to represent an IP address with two fields: Host

; isizeof(b)/sizeof(Student); i++) - { Wu b[i].show (); - } AboutCin.Get(); $}View CodeUnfortunately, the program can not be compiled successfully, why?Because: the class is an abstract concept, not an entity, and cannot contain attribute values (here is the argument of the constructor), only the object occupies a certain amount of memory space, contains a definite attribute value!See: Http://pcedu.pconline.com.cn/empolder/gj/c/0503/568909.html.3. Calls to constructors and

initial value set, the compiler automatically generates a default static constructor. The default initial value of a global variable for a simple value type is 0 because the entry function is in class B, so the program first loads B, and because Y is a static member of B, the value of Y is computed when the class is loaded, but the value of Y is found to be obtained by assigning a value, and the value of x is immediately computed. X is initialized by the static constructor of Class A, and refe

target file in place of the function: Underscore + function name, while the standard calling convention is in the form of an underscore + the name +@x, and X is returned. where x represents the number needed to clean up the stack. For example:The Windows driver needs to use the standard calling convention, and for the DriverEntry function, the system will look for [email protected] as the driver's entry, but the VS2010 default is the C language calling convention. So there is only _driverentry,

, adjusting spacing, and so on.The order of the controls can be set at design time by selecting the controls you want to set, selecting the order under the format, and then clicking the put to bottom (or top-level) command to set.The control's alignment action is designed with the SHIFT or CTRL feature to select multiple controls, select the Alignment command under formatting, and pop up the alignment menu. Choose the alignment that applies to you.Using VS2012 is relatively easy, and the basic o

written in one programming language can communicate with code written in another language. Because the type is fundamental to the CLR, Microsoft has specified a formal specification called a "Common type System" (Common type Systems, CTS) that describes the type definition and behavior.Using the rules specified by the CTS, the Assembly establishes a visual boundary for a type, and the CLR enforces (implements) these rules. In fact, there is no need to learn the CTS rules in this province, and t

interfaces commonly used in the NET Framework:Generic class DescriptionThe list corresponds to the ArrayList collection class, which dynamically adjusts the collection capacity, accesses the object in an indexed manner, and supports sorting, searching, and other common operations.The SortedList corresponds to the SortedList collection class, which represents Key/value to the collection, similar to the SortedDictionary collection class, and SortedList has an advantage in memory.The queue corresp

The original driver development was WDM (Windows Driver Model), when Microsoft introduced the DDK (Driver Developer Kit) tool.Now Microsoft is upgrading from WDF (Windows Driver Foundation) to replace WDM, while introducing the WDK (Windows Driver Kit) tool.Installing the WDK requires the minimum system for win XP SP3 above.Recommended use of ide:vs2010First, the difference between the WDM(1) The former uses the process-oriented, the latter can use object-oriented.(2) The former can develop bus

1. Java What are the basic data types in? How many bytes each? What are the reference data types in Java? What encoding does the char type use in basic data Java?byte byte 1 byte, short shorter integer 2 byte, int integer 4 byte, long length integer 8 bytes, float single precision 4 byte, double double type 8 byte, char character type 2 Byte, Boolean Boolean 1 byte;Java Reference type: class, array, interface;Java basic data type, which holds the address of the object that the data, Java refe

short freshness period for parent content : In order for the previous mode to work correctly, the contents of the container class should be set to a short freshness period, or not all cached. This is usually an HTML page that is used in other assistance content. This HTML page will be downloaded frequently, allowing it to respond quickly to changes. The supporting content can therefore be cached as much as possible. The key is to strike a balance, to cache as much as possible, and to preserve

thread begins with the initial function. For the first program, its initial function is main, which can be specified in the constructor of the Std::thread () object for our newly created thread.In the second procedure, the program consists of two threads: the initial thread starts at main, and the new thread starts with Hello. This specifies the initial function of the new thread T as hello.The new thread starts up and runs with the initial process, and the initial thread can wait or not to wai

, its permissions are set to ensure the security of the user being accessed.4. MultithreadingMultithreading has been the most successful application in the operating system. Multithreading refers to allowing an application to have two or more threads at the same time to support transactional concurrency and multi-tasking. In addition to the built-in multithreading technology, Java defines classes, methods, and so on to establish and manage user-defined multithreading.5. easy to useJava source