Java Learning Path (i) Installation of JDK

First, the operating mechanism

The Java source program is compiled by the compiler into platform-independent bytecode, the bytecode is interpreted by the virtual machine, the virtual machine sends each byte code to be executed to a specific platform interpreter, the interpreter translates it into the machine code on the corresponding platform, and then runs on the platform, And because the runtime still retains the explanation, this ensures that the Java program can cross the platform. Java is a strong type of language between the compiled and interpreted languages, and the so-called compiled language, like C/s, and so on, can only be compiled at runtime, without explanation, and only on specific platforms, while the interpreted language is the machine instruction that the interpreter is responsible for translating into a specific platform each time it runs. Each time you run it, you need to explain it once. So Java's cross-platform model is largely due to its virtual machines.

Second, JDK installation

I use the Win7 64-bit flagship of the system, the download is JDK 1.7.0, the following is the installation, environment variable configuration, validation process:

1. Install JDK Select Install the installation directory during installation, two installation prompts appear. The first time is to install the JDK, and the second is to install the JRE. Two installs are installed in a different folder in the same Java folder, as shown in 1-1:

Figure 1-1

2, install the JDK can choose the installation directory of the default installation directory \java before the directory changes, after the installation of the JDK, we will continue to install the JRE,JRE installation directory must be installed with the JDK in the same parent directory, here please note, if there is no installation directory requirements, can be fully default settings, No need to make any changes, you can click the next step directly. Install step 1-2 as follows:

Figure 1-2

3, JDK and JRE after installation, we need to do a manual configuration of the environment variables, the configuration of the process 1-3 is shown:

Figure 1-3

4. Create a new system variable in the environment variable java_home, the value of the variable fill in the JDK installation directory (D:\Java\jdk1.7.0)

5, configure the PATH environment variable, find the PATH environment variable in the system environment variable, and edit the variable value in the PATH environment to add%java_home%\bin;%java_home%\jre\bin; (Note: The semicolon following the value of the variable must pay attention to the format of the fill), 1-4 is shown below:

Figure 1-4

6, in the system variable to create a new classpath environment, the variable value is.; As shown in%java_home%\lib;%java_home%\lib\tools.jar,1-5, the configuration process is complete, even when the configuration is finished.

Figure 1-5

7, check whether the configuration successfully run the CMD input java-version (note: Variables separated by a space), 1-6, after the verification is complete, if the information that appears is the configuration succeeds, if not, then the configuration fails.

Figure 1-6

Java Learning Path (i) Installation of JDK