The first chapter of the Java Core Technology volume I contains three points:
1:key term for the Java White Paper: 11 keywords that describe Java: 2:java Applet3: Common Misconceptions about Java1: Chapter One: Key terminology of the Java White Paper: 11 keywords that describe Java:simplicity, object-oriented, distributed, robust, security, architecture-neutral, portable, interpretive, multi-threading, high performance, dynamicsections are described below:simplicity: Java syntax is equivalent to C + +, a "pure version",Java removes header files from C + +, pointer operations (pointer syntax), structs, unions, operator overloads, virtual base classes, and so on. In general, removing these relatively complex grammars is more beneficial than cheating. Object-oriented: Java is a purely object-oriented language, with object-oriented emphasis on data (objects) and object interfaces. in Java, "Everything is Object", that is, all the data is an object, including numbers, letters, etc., all classes of the base class are directly or indirectly inherited and Object,java without multiple inheritance in C + +, but can be implemented through the interface to achieve multiple inheritance requirements ( A class in Java can inherit only one class, but multiple interfaces may be implementedRobustness: Java code Early security issue detection, late dynamic (runtime) detection, the use of the pointer model can eliminate the possibility of rewriting memory and corrupt dataJava uses pointer model to avoid a series of pointer problems such as C + + field pointers.security: Java is used in a network/distributed environment to build anti-virus, tamper-proof systems, including:run-time stack overflow that destroys memory outside of its own process space and reads and writes files without authorization. The non-trusted code executes in the sandbox environment and does not affect the main systemarchitecture-Neutral: The compiler generates an architecture-neutral target file format, which is a compiled code that can be executed on the processor as long as there is a Java runtime system. Portability: Java data types have fixed size, such as int type in C + + based on 32 bit system bit 16 bit, 64 bit system bit 32 bit, in Java forever bit 32 bitthe reason is that Java code requires the virtual machine to interpret the machine code, and then give it to the operating system to execute,knowledge about virtual machines: Make a flag and write a blog. 22686433Multithreading: Java is the first mainstream language to support concurrent programming 2:java AppletJava programs that run in Web pages become applets. To use applets, you need a Java-enabled web browser to execute bytecode. 3: Common Misconceptions about Java1 Java is an extension of HTML. Java is a programming language, and HTML is a way of describing the structure of a Web page. 2 Use XML, no Java required. XML is a way of describing data. 3 Java will be the Universal programming language for all platforms. theoretically feasible, actually different platforms have more suitable languages, such as doing iOS development will use Oc,swift, browser processing with JavaScript,Windows programs typically have the advantage of using C++,c#,java for server-side programming and cross-platform client applications4 Java is interpreted, so it is too slow for critical applications. early Java is interpreted, now Java Virtual machine for the immediate compiler, Java code is running at the same speed as C + +5 JavaScript is a simple version of Java. Java is a programming language, and JavaScript is the scripting language that is used in Web pages.
Java Pros and misunderstandings
