core java book

Running a Java program in a Web page is called an applet.ReflectionThis feature is used extensively in JavaBeans, which is the architecture of Java components.A program capable of analyzing classes is called reflection (reflective). The function of the reflection mechanism and its powerful, as can be seen below, the reflection mechanism can be used to: Ability to analyze classes in the run View obj

time.Look directly at an example:public class program{static void Main (string[] args) { UI layer = new UI (); Layer. Setdataaccessor (New Xmldataaccessor ()); Layer. Do (); }} class ui{dataaccessor m_accessor; public void Setdataaccessor (Dataaccessor accessor) {m_accessor = accessor;} public void does () { m_accessor. GetUser (); }} interface dataaccessor{void GetUser (); void RegisterUser ();} class xmldataaccessor:dataaccessor{public void GetUser () {} public void RegisterUser () {}}Th

The ArrayList of the Core Java thing.　　High-rise ground, Java Foundation to pick up. Today, I looked at the core Java from the basic point to find a little bit to share.First of all, the professional-level Lucky Star actor---employee Class (PS: I am focused on Lucky Star 30)

) Data type conversions A solid arrow in the diagram indicates a loss-free conversion, and a dashed arrow indicates a conversion that may have a loss of precision. (e.g. 123 456 789 (int) is a large integer that contains more bits than can be expressed by the float type (a valid number 6~7 bit), and when this integer value is converted to float, the result is the same size, But the loss of a certain degree of accuracy (after the number of decimals can not be ac

First, to talk about final, finally, finalize the difference.Final modifier (keyword) If a class is declared final, it means that it can no longer derive a new subclass and cannot be inherited as a parent class. Therefore, a class cannot be declared abstract and declared final. Declaring variables or methods as final ensures that they are not changed in use. A variable declared as final must be given an initial value at the time of declaration, and can only be read in subsequent references and c

Core Java- concept Chapter If you need to know which Unicode characters belong to the Java alphabet, you can use the Javaidentifierstart and Javaidentifierpart methods of the Charactor class to detect Const is a reserved word for Java, but it is not currently used An integer that is 0 apart will produce an exception

(); to } +}Exception in thread "main" Java.lang.RuntimeException:call aAt Com.eyu.onequeue.testexception.a (testexception.java:12)At Com.eyu.onequeue.TestException.demo (testexception.java:30)At Com.eyu.onequeue.TestException.main (testexception.java:5)caused By:java.lang.RuntimeException:call bAt com.eyu.onequeue.testexception.b (testexception.java:21)At Com.eyu.onequeue.testexception.a (testexception.java:10)... 2 morecaused By:java.lang.RuntimeException:call CAt COM.EYU.ONEQUEUE.TESTEXCE

Nio:new IOStarting with JDK1.4, the new IO, which can map a disk file into memory, we then read the data in memory.stored in the Java.nio packageJava NIO (new IO) is a new IO API introduced by the Java1.4 version, which can replace the standard Java IO API, which is now primarily used in servers, and is sufficient for us to write code that still uses traditional IO.Java NiO provides a different way of working with iOS than standard IO:Channels and buf

This section begins the Java Multithreaded Programming learning, the basic concepts of the operating system, processes, threads are no longer mentioned, just understand Java for multithreaded programming support.First, inherit the thread class to create threadsThe Java language uses the thread class to represent threads, and classes that represent threads can imp

Thread pool is a key point to be mastered in multi-threaded learning.The cost of starting a new thread is higher because it involves interacting with the operating system. In this scenario, using the thread pool can improve performance, especially if you need to consider using a thread pool when you want to create a lot of short-lived threads in your program.I. How do I create a thread pool??Before Java5, the thread pool was developed manually, and from Java5 onwards,

have different implementationsMethod definitions in Java--------------------------1) A method allows the presence of multiple modifiers, with no order of precedence between multiple modifiers2) The return type is located after the modifier, and a method must have a return typeFor methods that do not return a value, the return type is void3) When there is a return value in the method, each branch in the method is required to have a return to ensure th

loaded by the sub-classloader cannot be converted to each other. It should be emphasized that all variables after the overloaded class is reinitialized, so some important data variables must be managed by the parent classloader. This method has some disadvantages. The core logic is combined to separate the variables, which affects the structure of the application. At present, this method should be used in a message service, mainly to avoid restarting

change methodThis is obviously more complex than providing a simple public data field, but it also has significant advantages(1) Can change the internal implementation, in addition to the method of the class, does not affect the other code(2) The Change method can perform error checking, but assigning a value directly to a domain will not be processedNote Do not write accessor methods that return references to mutable objects.3.4 Class-based access rights(1) A method can access the private data

Core java Chapter 4 notes, corejava Import java. util. *; public class Employee {private static int nextid = 1; private String name; private double salary; private int id; public Employee (String n, double s) {name = n; salary = s; id = 0;} public String getname () {return name;} public double getsalary () {return salary;} public int getid () {return id ;} public

/dopost-destroy destroy)The difference between > and CGI is that the servlet is in a server process, it runs its service methods in a multithreaded manner, an instance can serve multiple requests, and its instances are generally not destroyed, and CGI generates a new process for each request, which is destroyed after the service is completed. So the efficiency is lower than the servlet.(servlet: Server process, multithreaded run service, one instance service multiple requests, not normally destr

The core concept of Java: interface (interface)Interfaces are at the same level as classes, and in fact, interfaces are a special kind of abstract class.For example: interface ia{} public interface:The public interface is similar to a class where a file can have only one public interface and is the same as the file name. A public interface and a public class cannot be defined in a file at the same time.In a

Java an overview of the core technology programmingI. Features of the Java languageSimple line: Learn from C + +, excluding the C + + infrequently used pointers, structures, etc., to increase garbage collection.Object-oriented: different from C + + is single inheritance, but can inherit multiple interfaces. Fully object-oriented language;Network skills: Socket,ft

Java core programming-File operations, javafile 1. Overview Access to the File system is required for each language. java provides the File class to create, rename, delete, operate on the File list, and determine whether the File or directory exists. 2. Operations on files/Directories The operations include: 1: Create an object. 2: determine whether it is a direc

interrupted by Interruptedexcetpion"); Thread.CurrentThread (). interrupt (); //The interrupt state is cleared when the interruptedexception exception is generated, all the interrupts are reset or thrown out for subsequent code to detect if an interrupt has occurred } if(thread.currentthread (). isinterrupted ()) System. out. println ("Sub thread is interrupted"); ElseSystem. out. println ("Sub Natural Stop"); } }; Thread T=NewThrea

p264~p267:1. errors may occur in the program: User input error, device error, physical limit error, code error2. If some operations are not completed due to an error, the program should : return a security state and be able to allow the user to execute some other commands;or allow the user to save all operation results and terminate the program in a proper manner.3. The task of exception handling : Transfer control from the place where the error occurred to the error handler that can handle the