A, JDK
1. Meaning: Java Development Kit.
2. The installation must be done before a Java development kit Download: https://www.oracle.com/index.html
3.Java including three large elements:
(1) JavaSE (Java Standard Edition), which is the basis must know will be
(2) JavaEE (Java Enterprise Edition)
(3) JavaME (Java Micro Edition)
Two, Java language features (open source, free, pure object-oriented, cross-platform)
(1) Simplicity: In contrast, for example, java not support multiple inheritance, C ++ supports multiple inheritance, multiple inheritance is complex; C ++ has a pointer, Java shielding concept pointer. So Java is relatively simple, the underlying Java language is implemented in C ++, not C language.
(2) object-oriented: Java is a pure object-oriented, more in line with people's mindset, easier to understand.
(3) Portability: Java programs can be done once, run everywhere, that is to say javanese program can run on windows operating system, without any modifications, pain javanese program can be put directly on the Linux operating system .
(4) Multi-threaded
(5) robustness: automatic garbage collection mechanism and related automatic garbage collection mechanism referred to as GC mechanism. Java language which fish garbage generated in the process you choose is automatically recovered, the programmer does not need to be concerned about.
(6) Security
windows operating system kernel and the Linux operating system kernel is certainly different, they both operating systems are different ways of executing instructions.
Solution: let Java programs run in a virtual computer, then referred to this type of computer JVM, Java virtual machine, and then deal with the underlying operating system.
Second, the source code:
Address: https://github.com/ruigege66/Java/
2.CSDN: https: //blog.csdn.net/weixin_44630050 (Xi Jun Jun Moods do not know - Rui)
3. Park blog: https: //www.cnblogs.com/ruigege0000/
4. Welcomes the focus on micro-channel public number: Fourier transform, backstage reply "gifts" to get big data learning materials.