Preface: Between before a friend and I communication, could you order a set of Java tutorial, I wanted to think well, both to give everybody to share Java basic knowledge, I can also to comb their own ideas, so from now on, I will update the three articles every day, and friends together to learn the basic knowledge of Java, To keep up with oh, do not lag behind, by all means avoid three days of fishing and two days of drying nets, I believe that a month later you can also achieve the effect of cooked exercise ~~~
Let’s share:
The Java tutorial
Public HelloWorld {public static void main(String[] args) {system.out.println (); }}Copy the codeThere are many students see this small example, began to think, I am not very good at English can learn? Please do not have such concerns, if it is difficult to watch the tutorial, I suggest you and the Power node Java video to watch, so that the effect will be better, let’s get to the point, straight to the topic:
Java is a programming language and computing platform first released by Sun Microsystems in 1995. Java is a technology for developing applications that can make the Web more interesting and useful. There are a growing number of applications and Web sites that only work when Java is installed. Java is fast, secure, and reliable. From laptops to data centers, from game consoles to scientific supercomputers, from mobile phones to the Internet, Java is everywhere!
New little white welfare is coming! ⒈ Java is divided into three systems: Java (J2SE) (Java2 Platform Standard Edition, Java Platform Standard Edition)
⒉ JavaEE(J2EE)(Java 2 Platform,Enterprise Edition, Java Platform Enterprise Edition)
⒊ JavaME(J2ME)(Java 2 Platform Micro Edition).
In 2006, SUN announced at the JavaOne conference that it was contributing the Java platform to the open source world under the GNU General Public License (GPL), The release includes Standard, Micro, and Enterprise versions. This is a change of “historic significance”.
⒈ The Java language is simple:
The Syntax of the Java language is close to that of C and C++, making it easy for most programmers to learn and use. Java, on the other hand, has discarded little-used, hard-to-understand, and confusing features of C++, such as operator overloading, multiple inheritance, and automatic casting. In particular, the Java language does not use Pointers, but references. It also provides automatic scrap collection so that programmers don’t have to worry about memory management.
⒉ The Java language is object-oriented:
The Java language provides object-oriented features such as classes, interfaces, and inheritance. For simplicity, only single inheritance between classes is supported, but multiple inheritance between interfaces is supported, and an implementation mechanism (implements) between classes and interfaces is supported. The Java language fully supports dynamic binding, while the C++ language only uses dynamic binding for virtual functions. In short, the Java language is a pure object-oriented programming language.
⒊ The Java language is distributed:
Java language supports the development of Internet applications. In the basic Java application programming interface, there is a Network application programming interface (Java NET), which provides libraries for network application programming, including URL, URLConnection, Socket, ServerSocket and so on. Java’s RMI (Remote method activation) mechanism is also an important means of developing distributed applications.
The Java language is robust:
Java’s strong typing mechanism, exception handling and automatic garbage collection are important guarantees for the robustness of Java programs. Discarding Pointers is a smart choice for Java. Java’s security checking mechanism makes Java more robust.
5. The Java language is safe:
Java is often used in network environments, where it provides a security mechanism against malicious code. In addition to the many security features of the Java language, Java has a security mechanism (ClassLoader) for classes downloaded over the network, such as assigning different namespaces to prevent substitution of native classes of the same name, byte code checking, It also provides a security management mechanism (class SecurityManager) for Java applications to set up security sentinels.
6. The Media Java language is architecture neutral:
Java programs (files with the suffix Java) are compiled to an architecture-neutral bytecode format (files with the suffix class) on the Java platform and can then be run on any system implementing the Java platform. This approach is suitable for heterogeneous network environment and software distribution.
7. Java is portable:
This portability comes from architecture neutrality, plus Java’s strict rules on the length of the various base data types. Java system itself also has a strong portability, Java compiler is implemented in Java, Java running environment is implemented in ANSI C.
8. The Java language is interpretive:
As mentioned earlier, Java programs are compiled into bytecode format on the Java platform and can then be run on any system implementing the Java platform. At run time, the Java interpreter in the Java platform interprets these bytecodes, and the classes required during the execution are loaded into the runtime environment during the join phase.
Its advantages are high-performance:
Java is indeed high performance compared to interpreted, high-level scripting languages. In fact, with the development of just-in-time (JIT) compiler technology, the speed of Java is getting closer to C++.
The Java language is the saddle multi-threaded:
In the Java language, a Thread is a special object that must be created by the Thread class or its children (grandchildren) class. There are two common ways to create a Thread: wrap an object that implements the Runnable interface as a Thread using a constructor subclass called Thread(Runnable), or subclass Thread and override the run method, creating the object as a Thread. It is worth noting that the Thread class already implements the Runnable interface, so any Thread has its run method, which contains the code that the Thread wants to run. The activity of a thread is controlled by a set of methods. The Java language supports simultaneous execution of multiple threads and provides a synchronization mechanism (synchronized) between multiple threads.
Learning The Java language is dynamic:
One of the design goals of the Java language is to adapt to a dynamically changing environment. Classes required by Java programs can be dynamically loaded into the runtime environment, or they can be loaded over the network. This also facilitates software upgrades. In addition, classes in Java have a run-time representation that enables run-time type checking.
History of Java James Gosling launched the Java language project in June 1991, one of his many set-top box projects. When gosling’s office housed an Oak tree, it was originally called Oak, eventually named Green, and later changed to Java.
Sun was the first to publicly release Java1.0 in 1995. It writes once, runs anywhere (WORA) and provides a popular platform with no-cost uptime.
On November 13, 2006, Sun published Java as free and open source software under the terms of the GNU General Public License (GPL).
On May 8, 2007, Sun completed the process to make all Java core code, free and open source, except for a small portion of the code, for which Sun does not own the copyright.
Java development tools: Ensure that at least 1 GB of Java language exists in the system. Other tools are listed as follows:
⒈ Linux system, Mac OS system, Windows 95/98/2000/XP, WIN 7/8 system.
⒉ Java JDK 7, 8……
⒊ Notepad editor or other editor.
_____ the IDE: Eclipse
Java version history The major releases of Java and their release dates are as follows:
▪ JDK 1.0 (January 23, 1996)
▪ JDK 1.1 (February 19, 1996)
▪ J2SE 1.2 (December 8, 1998)
▪ J2SE 1.3 (May 8, 2000)
▪ J2SE 1.4 (February 6, 2002)
▪ J2SE 5.0 (September 30, 2004)
▪ Java SE 6 (11 December 2006)
▪ Java SE 7 (July 28, 2011)
▪ Java SE 8 (March 18, 2014)
▪ Java SE 9 (September 21, 2017)
▪ Java SE 10 (March 20, 2018)
▪ Java SE 11 (September 25, 2018)
▪ Java SE 12 (19 March 2019)
▪ Java SE 13 (17 September 2019)
▪ Java SE 14 (17 March 2020)
Why is Java the most widely used? From the Internet to enterprise platforms, Java is the most widely used programming language for:
⒈ Java is a cross-platform language based on JVM virtual machine, written at one time and run everywhere.
⒉ Java programs are easy to write, and have built-in garbage collection, do not have to consider memory management;
The Java virtual machine (JVM) has industrial-grade stability and highly optimized performance, and has been tested for a long time.
It has the broadest open source community support and a variety of high-quality components are readily available.
The Java language has long dominated three markets:
⒈ Internet and enterprise application, which is the long-term advantage and market position of Java EE;
⒉ Big data platforms, mainly Hadoop, Spark, Flink, etc., are developed by Java or Scala(a programming language running on the JVM);
(C) Android mobile platform.
This means that Java has the broadest job market.
Ava Language Overview Knowledge framework:
There are Java programmers all over the world right now, and you’re not alone wherever you go, because your Java programming buddy is with you. Let’s take a look at the world’s top programming languages TIOBE (www.tiobe.com/tiobe-index…
If you’ve been paying attention to the programming language rankings, you’ll notice that Java has been in the top two for many years, and in most cases has been ranked number one.
This is the first section of today’s “Java tutorial and Java language overview” share, next for everyone to sort out the second section of today’s “Java language history and Java language features”, soon updated ~~~
Also welcome everybody exchange discussion, if this article has incorrect place, hope everybody many forgive.
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