How to run java from command line?
This document instructs you on how to use the Linux shell with Java.
Let's assume you have already installed Java and have
Compile & Run simple program
If you have simple Hello World in current directory,
$ ls Hello.java
then compiling and runnig is pretty easy:
$ javac Hello.java $ ls Hello.class Hello.java $ java Hello Hello, Men!
NOTE #1: when you compile the src, include the
NOTE #2: be sure to omit a trailing
.classextension, when execute a program!
If you get an error during executin like
Exception in thread "main" java.lang.NoClassDefFoundError
try to use
java -cp . Hello
If it succeed, your java-classpath is set incorrectly.
Compile and Run a program with package
If you have a project, or java-file from eclipse with package, there is a small trick:
you should use fully qualified name (with package name and correct directory structure), otherwise you will get an error
Exception in thread "main" java.lang.NoClassDefFoundError: Hello (wrong name: com/bitthinker/Hello) bla bla blah ...
So, to resolve it, let's assume your Hello.java in inside com.bitthinker pachage, so, you should have the following dir-structure:
/workspace /com /bitthinker Hello.java
Then, the whole trick if you are in
workspace folder is (be patient):
$ javac com/bitthinker/Hello.java $ java com.bitthinker.Hello Hello, Man!
For more information, see Useful links section :)