Run Javac report Javac not internal or external commands, but running Java, java-version Normal

I've never had a JDK before. Today's situation, a variety of solutions to try the afternoon, finally came out, say the solution: Java_home, classpath are all in the system variables set up; Java_home Add the JDK installation directory, note java_home  to write correctly: Do not add semicolons behind the installation directory. The corresponding value of classpath is     .; %java_home%\lib\dt.jar;%java_home%\lib\tools.jar   Note This place don't miss the front point. Add after the original path value  ;%java_home%\bin;%java_ After the Home%\jre\bin is determined, restart  the cmd input javac  This time it will be useful. Remember to restart OH. There are all the Internet on the front, what do I meet today? Is that I wrote Java_home javahome less _   , but I use the back of the%java_home% so wrong, because I did not establish the JAVA_HOME environment variable I built is javahome, so wrong. Plainly java_home is a variable name that corresponds to the value of the variable, but if the variable name of the declared variable and the variable name used is different, how can it, hehe, this principle and programming. Students, we must pay attention to this problem, and so on other variable names should also pay attention to whether the correct.

　　

Run Javac report Javac not internal or external commands, but running Java, java-version Normal