Java cannot be found or the main class cannot be loaded

1 Test class When suddenly encountered a very strange problem, the Internet search a lot of information to find a solution, most of the situation is because the class added the package name compiled, execution time did not go to the package execution. It's not the same as the situation I met.

　　question: wrote a Test class, and Javac test under CMD. Java can compile and generate the test. class file, but the error occurs when it executes:

　　Java Test

1 c:\>java test2 Error: The main class test could not be found or could not be loaded

You can be sure that the environment variable is not a mismatch because there is no problem with executing Java and JAVAC commands directly. Many friends have encountered this problem because the class has been added to the package name. The Java file does not cause the same path as the. class file, and my test class does not have any package names.

Solution:

① can be%classpath by JAVA-CP; Test command to execute with the correct result:

1 C:\>java-cp %classpath; Test2 Hello Servlet

② uses echo%classpath or set Classpath to view the CLASSPATH environment variables and discovers that only the current user's Classpath value is displayed, and the CLASSPATH variable in the system does not have the absolute path of the JDK Lib: .;D: \ program Files\java\jdk1.7.0_80\lib; 。 In retrospect, when the JDK was first installed, it was not configured with Classpath, and after the compilation passed, the corresponding. class file could be executed under the current folder.

Why the error now, and carefully check the system variables found in the configuration of classpath, but there is no jdk Lib path, .;D: \ program Files\java\jdk1.7.0_80\lib; , in order to be able to access the Servlet-api.jar package under Tomcat anywhere in the system, configure the CLASSPATH in the system variables, and come here to understand why the above problem arises.

After installing the JDK, do not configure classpath in the system variable (that is, there is no such variable in the system variable), if the classpath variable is added, it must be configured with the Lib absolute path of the JDK.

It is verified that removing the Classpath,java Test command from the system variable executes successfully, and if you add classpath it is necessary to add the Lib absolute path on the JDK:.;D: \ program Files\java\jdk1.7.0_80\lib; The Java Test command can also be executed successfully.

Java cannot be found or the main class cannot be loaded