Basic Usage
Suppose we have a package called org.mypackage containing the classes:
- HelloWorld (main class)
- SupportClass
- UtilClass
and the files defining this package are stored physically under the directory D:\myprogram (on Windows) or /home/user/myprogram (on Linux).
The file structure will look like this:
| Microsoft Windows | Linux |
|---|---|
| D:\myprogram\ | ---> org\ | ---> mypackage\ | ---> HelloWorld.class ---> SupportClass.class ---> UtilClass.class | /home/user/myprogram/ | ---> org/ | ---> mypackage/ | ---> HelloWorld.class ---> SupportClass.class ---> UtilClass.class |
When we invoke Java, we specify the name of the application to run: org.mypackage.HelloWorld. However we must also tell Java where to look for the files and directories defining our package. So to launch the program, we use the following command:
| Microsoft Windows | Linux |
|---|---|
| java -classpath D:\myprogram org.mypackage.HelloWorld | java -classpath /home/user/myprogram org.mypackage.HelloWorld |
where:
- -classpath D:\myprogram sets the path to the packages used in the program (on Linux, -classpath /home/user/myprogram)
- org.mypackage.HelloWorld is the name of the main class
Note that if we ran Java in D:\myprogram\ (on Linux, /home/user/myprogram/) then we would not need to specify the classpath since Java implicitly looks in the current working directory for files containing classes.
Read more about this topic: Classpath (Java), Setting The Path To Execute Java Programs
Famous quotes containing the words basic and/or usage:
“There’s one basic rule you should remember about development charts that will save you countless hours of worry.... The fact that a child passes through a particular developmental stage is always more important than the age of that child when he or she does it. In the long run, it really doesn’t matter whether you learn to walk at ten months or fifteen months—as long as you learn how to walk.”
—Lawrence Kutner (20th century)
“Pythagoras, Locke, Socrates—but pages
Might be filled up, as vainly as before,
With the sad usage of all sorts of sages,
Who in his life-time, each was deemed a bore!
The loftiest minds outrun their tardy ages.”
—George Gordon Noel Byron (1788–1824)