Assalam-o-Alakum:- I am learning a new topic called packages. interesting one but there is a problem, I am unable to understand untill now how we compile a package which have two or more classes and how to run a package. So, if some one answer me I am very thankful to him. I know packages but the problem is for command to compile and run the packages.
Adnan You cannot compile or run a package in java. Package is something used to avoid name collisions. Its like a namespace and has an hierarchy. for example.... in my .jar file there are two classes Person.class - under com/prasad Person.class - under com/prasad/Misc if this jar file is in the classpath and I try to compile the following code I get compiler errors Person = new Person(); because the compiler doesnot know which Person to refer. to make it clear to the compiler I refer them I can refer like this.... com.prasad.Person n = new com.prasad.Person(); or com.prasad.Misc.Person n = new com.prasad.Misc.Person(); another way to do this is.. importing the specific package forexample import com.prasad.*; Person = new Person(); or import com.prasad.Misc.*; Person = new Person(); but you cannot import both packages when you create a new Person Object import com.prasad.*; import com.prasad.Misc.*; Person = new Person(); The compiler complains about the ambiguity. Now how to create a package? Just write this statemet at the begining of your .java file package <packagename> example: package com.prasad; public class Person { .... } package com.prasad.Misc; public class Person extends xxx { ..... } Hope this helps cheers Siva
Hello Adnan! for compiling yr. java files with package notation intact use the following. c:>javac -d AnyJavafile.java then it creates a directory structure with yr.package name as parent to the class file. for execution of such class files use the following java package.anyclassfile Nageswara
By the way, Java life is easier if you remember this rule: ALL class names must ALWAYS be qualified with their package. (By default java imports "java.lang,*", which make this rule less obvious.) For example, to reference class A in package mypackage you must code "mypackage.A" or use an import statement. If "A" has a main method then you run it by passing "mypackage.A" to java. This assumes your classpath is set. I.e., that your classpath includes the root location where directory "mypackage" is found.
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