I cant generate CUP parser and JFlex scanner in cmd

Question

i'm new in compiler . i've read that i can generate xxx.flex file in cmd by this code :

java JFlex.Main xxx.flex

but i got this error :

Error: Could not find or load main class JFlex.Main

and for generating yyy.cup , i typed :

java java_cup.Main yyy.cup

but i got this error too :

Error: Could not find or load main class java_cup.Main

i confused ... what should i do ?

Seki Seki · Accepted Answer · 2016-08-06T00:28:30

When you are invoking

java JFlex.Main xxx.flex

You ask java to load the JFlex.Main class and passing xxx.flex as parameter. As you do not tell java where is that JFlex.Main class, java is searching it in its classpath, and if you did not add the JFlex jar file to the class path, it results in the error message

Error: Could not find or load main class JFlex.Main

BTW, class names and namespaces are case-sensitive : in the JFlex jar file, the Main class is in the jflex directory, not JFlex so you need to invoke the jflex.Main class... unless you are using the a JFlex version prior to 1.5 where JFlex is legal.

To let java find the class:

either change the system class path (with the environment variable $CLASSPATH- or %CLASSPATH% in windows)
or just provide the location of the jar file the the java command with the -cp parameter

For example:

java -cp path/to/jflex-1.6.0.jar jflex.Main xxx.jflex

If the jar is in the current directory, you can just use

java -cp jflex-1.6.0.jar jflex.Main xxx.jflex

Or more simply, as it is an executable jar, you can omit the main class

java -jar jflex-1.6.0.jar xxx.jflex

Similarly, it seems that java is missing the CUP jar file while processing your yyy.cup file, you can fix it like for JFlex with

java -cp java-cup-11a.jar java_cup.Main yyy.cup

or

java -jar java-cup-11a.jar java_cup.Main yyy.cup

I cant generate CUP parser and JFlex scanner in cmd

1 Answers