core java syllabus

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

) proxy.newproxyinstance ( fly.getclass (). getClassLoader (), new class[] {flyable.class}, new Objecthandler (fly)); } public static void Main (string[] args) { flyable fly = Flyfactory.getflayimpl (); Fly.addwing (null); System.out.println (Fly.fly ());} }Core Class Description:The JDK provides a class named Proxy.newproxyinstance (All-in-one). Where is the first parameter for the loader th

Exception handlingThe parent class in the exception structure Throwable class, its Exceptionlei class and the error class. What we can catch in the program is the subclass exception of exception.Error at System level: Error in Java Runtime Environment, we are not controllable.Exception is a program-level error: we can control it. 1) catch Exceptions in two ways: one is to add Try-catch to catch the exception, and the other is to declare the exceptio

the source file. If you do not place the package statement in the source file, the class in the source file is placed in a default packet.The compiler does not check the directory structure when compiling the source files. So as long as the source file is not dependent on other packages, the compilation error does not occur even if it is not in the declared package, but a run error occurs because the virtual machine cannot find the file.Package Scope:The parts marked as public can be used on an

Java core programming-byte stream of IO stream (2), javaio 1. byte stream A 1.1-byte stream is a stream that operates byte. Byte streams can operate on any data, such as media data, music, movies, and images. Of course, they can also operate on characters. Byte stream is based on byte stream, we know that a byte is 8 binary bits, a byte corresponds to an English character in the UTF-8, people found that usi

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

(); 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

main element between, child elements and child elements between the space also forget. If you only want to get child elements, you can do this:NodeList children = Root.getchildnodes ();for (int i=0;iNode child = Children.item (i);if (child instanceof Element) {Element childelement = (element) child;...}}This processing is still very troublesome, this is why the subsequent introduction of the DTD, the DTD can be used to standardize the content of XML, reduce some unnecessary validation process.L

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,

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

the action within the specified time, the thread stateAutomatically to operational (RUNNABLE).6) TERMINATED (thread end)When the thread executes at the end, it is in state, and this is when the thread's life cycle terminates.There are two cases of thread termination:One is normal end returnThe other is because the exception was previously terminated3. Key code to start a thread in JavaFirst, we have to know that the Runnable interfaceThe Runnable interface has a run () method that is used to st

In fact, with the previous article "the prelude to learning DES encryption algorithms" as the basis, it is easy to implement the DES algorithm.However, I found the source code from the Internet, written in Java, and written in C ++, but all the code seems to be the same. Why is it the same? At the beginning, I wrote a class and added all the methods to the class. I guess it would be hard to implement it once if it wasn't the author's skill. In additio

)throwsException {String identifier=Generatelicensekey (); SYSTEM.OUT.PRINTLN (identifier); }}Get JVM DataJVM data is an important set of parameters to monitor the application, the general local development can be connected to the corresponding process by jconsole to view the relevant metrics data, but the online environment is not suitable for viewing through the jconsole, so we now use Java code to obtain data, Then report it out and then show it

I. Overview of new Java IOThe input and output streams in the Javaio are handled through byte movement, and the stream-oriented input-output system can handle only one byte at a time, so it is inefficient and the traditional input-output stream is blocked, meaning that when the data is unreadable, the current thread is blocked until it is read to a valid data to continue running.After java1.4, a series of improved input and output classes and methods

1. three main features of the process:Independence: With its own independent address space, a process cannot directly access the address space of other processes.Dynamic: is a collection of instructions that are active in a system.Concurrency: A single process can be performed concurrently on multiple processors, with no impact on each other.2. Differences in concurrency and parallelism:Parallel is the same time, there are multiple instructions on multiple processors at the same time, concurrenc

Java core --- AnnotationAnnotation is a new feature in jdk 5 and later versions. Spring and Hibernate frameworks provide annotation configuration methods. This article describes the annotations in the middle of the wave breeze and mainly explains the usage of jdk built-in annotations, the declaration and definition of annotations, as well as the usage of custom annotations are at the beginning, to say a lit