Java Project (2)--java Development Environment Configuration | JDK and JRE

C-Disk expansion-Repair oracle--Modify the registry--windows cannot start-redo the system-reconfigure the Java development environment, plus the operating test system, these three days are like a dream. Write a small summary of the Java Development Environment configuration, do anything needed is a way of thinking, To know the ins and outs, or you will die very miserable.

The basic steps are a series of installations:

1. JDK
2. Oracle Server Client
3. Plsql
4. MyEclipse
5. Configuring the MyEclipse JDK and Tomcat
6. Setting environment variables (JDK and Oracle)
7. Plsql Connecting to Oracle

  

In the configuration process found that some tutorials involved in the configuration of the JRE, but the previous project did not mention the JRE ah, so I checked the data, understand the Java development and operation of many reasons. Here are the main things to talk about the differences between JDK and JRE.

Jre:java Runtime Environment The operating environment of the Java program. since it is a running environment, you must include the JVM (virtual machine) and the class file of the Java class Library.  

Jdk:java Development Kit Java the development Kit for the program contains various class libraries and tools.

So what's the relationship between the two of them?  

From the path, there is a JRE under the JDK. What does that mean?

In fact, java\jdk\bin this bin has a variety of Java programs need to use the command, and the difference between Java\jdk\jre\bin and Java\jre\bin is the former javac.exe. Because the JRE is just a running environment and does not need to be compiled, It has nothing to do with development. In this case, CLIENT\JVM and SERVER\JVM are available under the JDK's own JRE because of the development capabilities. Why is that?  

To put it simply, the JRE is like a PC, and Java runs on it just as the written Win32 application runs on the operating system. There are many development tools in the JDK, like Javac.exe,jar.exe, they are written in the Java language, they run in the JRE, We must run these javac.exe tools, the JDK, to compile or run the programs we write. Therefore, the JDK must have a JRE in it. Further, when we run the program, Java.exe will go to the appropriate JRE (there are several times in our computer), It first looks at its own directory there is no JRE, the parent directory has no, registry ...

Java Project (2)--java Development Environment Configuration | JDK and JRE