- A company that develops the Java language?
Developed by Sun Microsystems, USA.
- 3 Versions of Java?
J2SE (JAVA2 standard Edition) version
EE (Java 2 platform,enterprise Edition) Enterprise Edition
J2ME (Java 2 micro Edition) Mini-version
In the new version after 5.0, it is called: javase java EE javame
- What are some of the main features of the Java language?
Platform agnostic: Capable of running on different platforms
Security: pointer operation removed, memory allocated by operating system
Object-oriented: Use classes to make programs more maintainable
Distributed: can use network files as easily as using native files
Robustness: Check for program compile and run errors
- Three core mechanisms of Java
Virtual machine mechanism: using virtual machine to interpret bytecode to execute Java program for cross-platform
Garbage collection mechanism: automatic memory recovery
Code security mechanism: Validate code after code is loaded and then execute code.
- What is a JDK?
JDK (Java Development Kit) Java Development Kit. This includes the JRE, which is a must for developers of Java to develop the tools to run Java programs.
- What is a JRE?
JRE (Java Runtime Environment) Java Runtime Environment, a collection of environments necessary to run Java programs, including the JVM standard implementation and the Java Core Class library.
- What is a JVM?
The JVM Java Virtual machine, a fictitious computer, is implemented by simulating various computer functions on a real computer.
- Operating system issues with JDK installation?
You must install a different JDK for different operating system downloads, such as installing a Linux-based JDK under Windows-Jdk,linux for Windows.
- What are the relevant environment variables that need to be configured?
Path: Used to search for external commands, such as the compiler's JAVAC command, the Java command to execute the program
Classpath: Used to search for classes, that is, class files, such as the ability to execute classes at different locations
- Common development tools that can write Java programs?
Notepad, Eclipse,myeclipse,jcreate
- Type of Java file?
There are two kinds:
File extension Java: is a Java source file, which belongs to a plain text file before compilation, storing Java source code.
file with the extension class: is a Java class file, which belongs to the compiled binary, storing the bytecode.
- How does Java compile and run?
First write the Java source file, then compile it into a class file, and then interpret it as machine code to hardware execution through the virtual machine.
- Is Java a compiled or interpreted language?
Neither fully compiled nor fully interpreted, semi-compiled and semi-interpreted.
8. Summary of "attached" Java basics
