You can run Java in cmd, but you can't use Javac solution __java

Cause: When Java is installed, the path of the JDK and the path of the JRE are selected as a result of overwriting. At this time you can not find Tools.jar and Dt.jar under LIB. Solution: 1. First uninstall Java, uninstall is very easy, directly to the two Java-related programs to uninstall the line (with Windows with the uninstall). After unloading you will also find that the original Java folder is empty.

2. Reinstall
Create a new Java folder in D and create two new folders under the Java file, named JDK and JRE, respectively.
3. Double-click the program to install, installation has two times the opportunity to choose the path, the first is to let you choose JDK installation path, select for D:\java\jdk, the second is to let you select the JRE installation path, select for D:\java\jre
4. After installation, the configuration of environment variables, computer right click Properties,-Advanced system settings-environment variables-Select the following system variables

5. New
Variable name: Path
Variable Value: C:\programdata\oracle\java\javapath;%java_home%\bin;%java_home%\jre\bin
New
Variable name: java_home
Variable Value: D:\JAVA\JDK
New
Variable name: ClassPath
Variable value:.; %java_home%\lib\dt.jar;%java_home%\lib\tools.jar;
The reason for setting the java_home to D:\java\jdk is because the Dt.jar,tools.jar generated during the installation is placed in the D:\java\jdk\lib directory, which is something that is JDK. Classpath use Java_home to make a relative path. So java_home must be the installation directory of the JDK, and there is no semicolon behind it, and if it has a semicolon, then%java_home%\lib\dt.jar is not a directory. Just try again, OK.