Setting classpath for Java

Question

I was trying to use a tool a tool written in java called "fastqc" (for people who are interested in what is fastqc. when I tried typing the command :" fastqc" I got the error:

Exception in thread "main" java.lang.NoClassDefFoundError: uk/ac/babraham/FastQC/FastQCApplication
Caused by: java.lang.ClassNotFoundException: uk.ac.babraham.FastQC.FastQCApplication
    at java.net.URLClassLoader$1.run(URLClassLoader.java:217)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:205)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:323)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:294)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:268)

when someone had similar previously,some one suggested that in similar case, I need to set the class path to the directory which contains FastQC installation:

and depending on having a standard class path or non-standard classpath on my machine, I need to append existing classpath like:

java -Xmx250m -classpath /usr/local/FastQC uk.ac.bbsrc.babraham.FastQC.FastQCApplication

or

java -Xmx250m -classpath /usr/local/FastQC:$CLASSPATH uk.ac.bbsrc.babraham.FastQC.FastQCApplication

Since my directory which contains the FastQC is /u32/myusername/Tool/FastQC

so I tried both:

java -Xmx250m -classpath /u32/myusername/Tool/FastQC uk.ac.bbsrc.babraham.FastQC.FastQCApplication

and

java -Xmx250m -classpath /u32/myusername/Tool/FastQC:$CLASSPATH uk.ac.bbsrc.babraham.FastQC.FastQCApplication

but none of them seemed to work.

Did I mess something up? I am not sure about what -Xmx250m means, with or without it, the path setting did not work. Sorry for my ignorance. Any idea or suggestion appreciated.

score 0 · Answer 1 · edited Jan 08 '20 at 12:07

well the easy step to do is go to install folder
copy the address of bin folder
open "My computer properties" -> "Advanced system setting" -> "Environment variables"
click on "New" and paste that address and name it as path if the address is in the bin and put ;
again, click "New", paste the address, remove bin and insert lib and name it as classpath
put ; after end
restart cmd
open cmd check by typing javac

That's it

Setting classpath for Java

1 Answers1