Abstract:Summary of Class Notes 1 Theory 2 Basic Logic if eise for while 3: 1: Java Language Programming Language Natural Language Computer Language 2: Programming Language Classification Based on Data Type Strongly Typed Programming Language Weakly Typed Programming Language: eg C language

Class notes 4.23

Summary
1 Theory
2 Basic logic if eise for while

3：

1: java language programming language natural language

计算机语言

2: Programming language classification

根据数据类型 强类型编程语言 弱类型编程语言 ：eg C语言

根据执行方式 编译执行---Java源文件---javac编程---java执行 Java----class

解释执行---shell脚本---.sh源文件---更改x权限---执行 C----a.out

3. Computer language classification compilation: Java, C, C

解释： shell、 Python、PHP

Comments : java is a language where compilation and interpretation coexist

C语言是纯正编译语言

4. Composition of programming language

×词法和语法规则 *编译器和解释器 ×开发中常用包 API ---工作当中经常用到 --application platform interface应用平台网络接口 ×集成环境IDE ---Integrated Development Environment

Note: JDK is also a simple IDE

Note: It is best to install software and apps 1~2 versions lower than the latest version

Note: The teacher recommends a book: "Self-Study Programming Language" //If you are interested in the language

Classification of Java language---- According to different applicable fields

----JavaSE 新（J2SE 旧）--必学的-- java 2 platform standard edition ----JavaME （J2ME）----用的比较少-- ----JavaEE (J2EE) ----大行其道--- JavaWeb //Java工程师----JavaEE----后台开发的

5. JavaSE(14day) ---Android API

---JavaEE-----Java后台开发工程师 ---BigData----大数据开发工程师(4month)

6.---JDK---//Development tool lib ---javac == ===Java Development kit & Java Development Kit

----JRE---// lib =====Java Runtime Environment =====Java Runtime Environment

----JVM---- Virtual machine//JRE and JVM are bundled together

//Learn more about java later "JVM Virtual Machine Principles"

7. Environment variables

---path-----classpath------JAVA_HOME

---Path system environment variable-----javac can be used everywhere

---clasPath----.java-----.class-----.java file storage directory

================ ==
export Path = $ Path
export classport

export JAVA_HOME

Path /tools/jdk/8/bin

Java_HOME tools/jdk/8 /---------IDE development tools//Note: Looking for Java development tools

8. Naming rules for indicators? ==========The class name is exactly the same as the file name

9. Data type

----基本数据类型-----Java默认存在 //数据类型 == 变量名== 初始值 -----引用数据类型 ---java存在的 -----Scanner -----自定义类 //类名 == 变量名==对象的初始值

//"Reference data type"-----from hadoop, project The beginning will involve reference data types

//Learn about the data types of C language

// -----Byte----Unit byte

-----byte----java整型变量的byte类型 -----bit-----比特 1010

//Countermeasures against fuzzy concepts======List similar word concepts for "comparison" to strengthen memory====A recommended learning technique

//========= ===============

How to listen to the class? How to practice? How? Efficiency in listening to lectures?
**'Write', 'Remember', 'Ask'==== "Ask" is very important
**Review and sort out in the afternoon
**Exercise
**Think =========Horizontal penetration========

10. Data conversion

Small---Large========No accuracy will be lost

Large---Small========Accuracy will be lost

Comments: Data type conversion will be tested during the interview

"Forced type conversion"---Read the courseware in advance

11. Data conversion of reference types

--- The numbers must be correct to force conversion---

==================================== ============================

public static -----void----- --- -main (String[] args)----

Modifier return value type method name (parameter list)

/**
Custom method steps:

*/

? ????
Return value type: There is a return value (return value is required) ----- Select ==== basic data type and reference data type

没有返回值 ------void

12. Homework 50 this week Job code

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Summary of the four and eight basic data types of Java

Java language cross-platform principle-JAVA Elementary introductory video tutorial

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