Java Language Introduction of Power Nodes Java College Collation

Java profile

Java is the collective name for the Java object-oriented programming language and Java platform launched in May 1995 by Sun Microsystems (now acquired by oracle). Developed by James Gosling and colleagues, it was officially launched in 1995. According to the official oracle Data Index, hundreds of millions of systems have been developed using Java worldwide.

Java is an object-oriented programming language, which not only absorbs various advantages of C++ language, but also abandons the incomprehensible concepts such as multiple inheritance and Pointers in C++, so Java language has two characteristics: powerful and easy to use. As a representative of static object-oriented programming languages, Java is an excellent implementation of object-oriented theory, allowing programmers to program in complex ways in an elegant way.

Java is simple, object-oriented, distributed, robust, security, platform independence and portability, multi-threading, dynamic and other characteristics. Java can write desktop applications, Web applications, distributed and embedded system applications, and more.

Java is divided into three systems:

The & # 61548; JavaSE (JSE) (Java Platform Standard Edition, Java platform standard version, old version abbreviated as J2SE)

The & # 61548; JavaEE(JEE)(Java Platform,Enterprise Edition, Java enterprise edition)

The & # 61548; JavaME(JME)(Java Platform Micro Edition)

In June 2005, JavaOne conference was held and SUN company opened Java SE 6. At this point, various versions of Java have been renamed to cancel the number "2" : J2EE to Java, J2SE to Java, J2ME to Java ME.

The main features

The Java language is simple:

The syntax of Java is close to that of C and C++, making it easy for most C or C++ programmers to learn and use. On the other hand, Java drops some of the little-used, hard-to-understand, and confusing features of C++, such as operator overloading, multi-inheritance, and automatic casts. In particular, the Java language does not use Pointers, but references. It also provides automatic waste collection so that programmers don't have to worry about memory management.

The Java language is object-oriented:

The Java language provides primitives such as classes, interfaces, and inheritance. For simplicity, it supports only single inheritance between classes, but multiple inheritance between interfaces, and the implementation mechanism between classes and interfaces (the key is implements). 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.
The Java language is distributed:

Java language supports the development of Internet application. There is one network application programming interface (Java net) in the basic Java application programming interface. It provides the class library for network application programming, including URL, URLConnection, Socket, ServerSocket and so on. RMI (remote method activation) mechanism of Java is also an important means to develop 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. Dropping Pointers is a wise choice for Java. The security check mechanism of Java makes Java more robust.

The Java language is safe:

Java is commonly used in network environments, so Java provides a security mechanism against malicious code. In addition to many of the security features of the Java language, Java has a security mechanism (class ClassLoader) for classes downloaded over the network, such as assigning different namespaces in case they replace local classes with the same name, bytecode checking, and providing a security management mechanism (class SecurityManager) for Java applications to set security sentinels.

The Java language is cross-platform:

Java programs (files suffixes.java) are compiled on the Java platform in an architecturally neutral bytecode format (files suffixes.class) and can then be run on any system that implements the Java platform (windows, mac, linux, etc.), literally compiling once and running multiple times. This approach is suitable for heterogeneous network environments and software distribution.

Java is interpretive:

As mentioned earlier, the Java program is compiled into bytecode format on the Java platform and can then run on any system that implements the Java platform. At run time, the Java interpreter in the Java platform interprets these bytecodes for execution, and the required classes are loaded into the runtime during the join phase. The & # 61548;

The Java is high performance:

Java is truly high performance compared to those high-level scripting languages that are interpreted. In fact, the speed of Java is getting closer to that of C++ with the development of the JIT(ES176en-ES177en-ES178en) compiler technology. The & # 61548;

Java is multithreaded:

In the Java language, a thread is a special kind of object that must be created by the Thread class or its children. There are usually two ways to create a thread: 1, using the constructor Thread(Runnable) to wrap an object that implements the Runnable interface into a thread, and 2, subclassing the run method and overwriting the run method so that the object created using the subclass is a thread. It is worth noting that the Thread class already implements the Runnable interface, so any 1 thread has its run method, and the run method contains the code that the thread is going 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 synchronization between multiple threads (the key is synchronized).

The Java language is dynamic:

One of the design goals of the Java language is to adapt to a dynamically changing environment. The required classes for the Java program can be loaded dynamically into the runtime environment or via the network. This is also good for software upgrades. In addition, the classes in Java have a run-time representation that enables run-time type checking.

The development history

The & # 61548; The Java language was born on May 23, 1995

The & # 61548; In January 1996, the first JDK-JDK1.0 was born

The & # 61548; In April 1996, 10 leading operating system vendors announced that they would embed JAVA technology in their products

The & # 61548; In September 1996, about 83,000 web pages were produced using JAVA technology

The & # 61548; JDK1.1 was released on 18 February 1997

The & # 61548; On 2 April 1997, the JavaOne conference was held with more than 10,000 participants, which was then the largest meeting of its kind in the world

The & # 61548; In September 1997, the JavaDeveloperConnection community had more than 100,000 members

The & # 61548; In February 1998, JDK1.1 was downloaded more than 2,000,000 times

The & # 61548; On December 8, 1998, JAVA2 enterprise platform J2EE was released

The & # 61548; In June 1999, SUN released three versions of Java: standard (JavaSE, formerly J2SE), Enterprise (JavaEE, formerly J2EE) and micro (JavaME, formerly J2ME)

The & # 61548; Es265 EN1.3 was issued on 8 May 2000

The & # 61548; Es269 EN1.4 was issued on 29 May 2000

The & # 61548; On June 5, 2001, NOKIA announced that it would sell 100 million mobile phones supporting Java by 2003

The & # 61548; J2EE1.3 was issued on 24 September 2001

The & # 61548; J2SE1.4 was released on February 26, 2002, and the computing power of Java has been greatly improved since then

The & # 61548; At 18:00 on September 30, 2004, PM and J2SE1.5 were released, marking another milestone in the development of Java language. To show the importance of this release, J2SE1.5 has been renamed to Java SE 5.0

The & # 61548; In June 2005, JavaOne Conference was held and SUN company opened Java SE 6. At this point, various versions of Java have been renamed to cancel the number "2" : J2EE

It was renamed Java EE, J2SE Java and J2ME ME

The & # 61548; In December 2006, SUN released JRE6.0

The & # 61548; On April 20, 2009, Oracle acquired Sun for $7.4 billion. Copyright java.

The & # 61548; In November 2010, Apache threatened to quit JCP due to Oracle's unfriendliness towards the Java community.

The & # 61548; On July 28, 2011, Oracle released the official version of Java7.0.

The & # 61548; In 2014, Oracle released Java8.0, which supports lambada expressions