Java Foundation _day1

Learning content:

The development history of 1.Java

2.JDK and JRE differences, features.

Download and installation of 3.JDK and JRE

4. Configuring the Environment, path and CLASSPATH

5.helloworld Program

6. Conversion between the binaries

7. Annotations, markers, constants

8. Common variable types

Summarize:

Java is developed by Sun, where the JDK is for developers, and the JRE is a tool for running Java programs, and the Java program is cross-platform because the virtual machine, where the JRE contains the virtual machine, and the JDK contains the JRE, Now the latest version of JDK is version 8.0, path is used on the Windows operating system to build the environment, where the path includes the bin directory, the bin directory contains the Java required tools, Java source program is the Java format, after Javac compiled into the class format, that is, bytecode format, cl Asspath is a required environment to run the class file, but it doesn't seem to need to be built.

HelloWorld Program:

public class hello{

public static void Mian (String args[]) {

System.out.println ("Hello world!");

}

}

class defines classes hello,public static void Mian is the main method, and curly braces are defined intervals of the program.

Java annotations contain single-line comments and multiline comments, where multiple lines of comments cannot contain multiple lines of comments.

Variable is a piece of space in memory to hold the data, the types of production variables are: integer, floating point, character type, Boolean type

Int

Byte

Short

Long

Float

Double

Char

Boolean

Java Foundation _day1