Java basic theory and programming language classification

Summary:Lesson Notes Summary 1 theory 2 basic logic if eise for while 3: One: Java language programming language Natural language computer language two: programming language classification based on data type strongly typed programming language weakly typed programming language: eg C language

Class Notes 4.23

Summarize
1 theory
2 basic logic if eise for while

3:

One: the Java language programming language natural language

        Computer language

II: Programming Language classification

            strongly typed programming language based on data type               weak type programming language: eg C language

           Compile Execution---Java source files according to execution---javac programming---java execution     java----class

                  Explains execution---Shell script---. sh source file---Change x permissions---Perform  C----a.out

Third, computer language classification and compilation: Java, C, C + +

               Explanation: Shell, Python, PHP

Note: Java is the language in which compilation and interpretation coexist

C language is a pure compiler language

Iv. Composition of programming languages

       x lexical and grammatical rules       * compiler and interpreter    x Common package API in development  ---work often using the--application platform Interface Application Platform network interface       x integrated environment IDE  -- -integrated Development environment

Note: JDK is also a simple IDE

Note: Installing software and apps is best less than one or two versions of the latest version

Note: The teacher recommends a book: self-study programming language//interest in language

The classification----of the Java language is based on different fields of application

  ----Javase New (J2SE old)--must learn--   Java 2 Platform Standard Edition  ----javame  (J2ME)----used less--  ---- Java EE   -------   javaweb   //java engineer----Java EE----Background development

V. Javase (14day)---Android API

       ---java EE-----background Development Engineer       ---bigdata----Big Data Development Engineer (4month)

Six 、---JDK---//development tools LIB---javac =====java Development Kit & Java Development Kit

----JRE---//lib =====java Runtime environment =====java operating environment

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

Let's look at the Java JVM Virtual machine principle later on

Seven, environment variables

---path-----classpath------Java_home

---the environment variable of the path system-----Javac can be used everywhere

---claspath----. java-----. class-----. the directory where Java files are stored

==================
Export PATH = $ path
Export Classport

Export Java_home

Path/tools/jdk/8/bin

Java_home tools/jdk/8/---------IDE Development Tools//Comments: Looking for Java development tools

Eight, the name of the expression rules? The ========== class name is exactly the same as the file name

Ix. Types of data

    ----Basic Data Type-----java default presence  //data Type = =  variable name = = Initial value   -----reference data type  ---java exists  -----Scanner                ----- Custom class  //Class name = = Variable name = = The initial value of the object

"Reference data Type"-----from Hadoop, Project starts with reference data types

Learn about the data type of C language

-----byte----Unit byte

   BYTE type-----byte----java integer variable   -----bit-----bit  1010

The strategy of fuzzy concept ===== lists similar word concepts for "contrast", to enhance memory = = = Recommended a learning Skill

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

How to lecture? How to Practice? How is the efficiency of lectures?
** ' write ', ' Remember ', ' ask ' = = ' ask ' is important
* * Review and comb the afternoon
** Practice
** want to ========= horizontal through ========

X. Data Conversion

Small---large ======= without loss of precision

Large---Small ======= will lose precision

Note: Data type conversion at the time of the interview

"Forced type conversions"---see Courseware in advance

Xi. data conversions for reference types

---numbers are correct to cast---

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

public static-----Void---------Main (string[] args)----

Modifier return value type method name (parameter list)

/**
Custom method Steps:

*/

?????
Return value type: have return value (need return value)-----select = = Basic data type and reference data type

        No return value  ------void

12, this week 50 job code