Java Learning JDK Configuration

1.JDK,JRE,JVM Introduction

1.1 What is a JDK

the JDK (Java Development Kit) is the Java Language Software Development Kit (SDK). In the JDK installation directory there is a JRE directory, there are two folders Bin and Lib, here you can think that the bin is Jvm,lib is the JVM to work the class library, and the JVM and Lib together is called the JRE.

1.2 What is a JRE

JRE (Java Runtime Environment,java Runtime Environment), contains the JVM standard implementation and the Java Core Class library. The JRE is a Java runtime environment and is not a development environment, so there are no development tools (such as compilers and debuggers)

Note: (so as a developer we can actually not install the JRE-because the JDK is already included)

1.3 What is a JVM

The JVM is the abbreviation for Java Virtual machine (Java VM), which is a specification for computing devices, a fictional computer that is implemented by simulating various computer functions on a real computer.

JDK JRE JVM Diagram (reference 51819046)

Above we learned what is the JDK and JRE and JVM below explains why to configure the path path

Two JDK path configuration

The JDK path configuration is actually configured with the Java compiler path

Why configure the path path so what is a path path?

What is the 2.1path path

When the computer executes a command, for example, we execute the javac command under DOS, the computer searches the current directory for an executable Javac program, and then selects the program on the system path path to execute the JAVAC command, and finally finds it in Win32. Otherwise it will not be found. This is the computer's discovery process. Now we can figure out why we have to configure path path. In fact, in order to solve our computer in any directory can find and execute Java compiler program.

Note (so we can also compile the Java program without configuring path, which can be cumbersome because you can only compile Java programs in the Javac directory--。 ）

2.2path path format

Path path using absolute path also called physical path

Format: X disk \x file

Example: D:\JAVA\JDK1.8\bin

2.3path Path Configuration process

A) Click the Start button to find this computer (Win7 computer)

b) Right-click Properties to find advanced system settings

c) Click Select Environment variable

d) Find the path selected in the system variable this edit creates a new path that will be configured to fill in.

Java Learning JDK Configuration