How do I run a Java class in a package?

Question

I have two java classes as follows

App1 without a package:

class App1 {
    public static void main(String[] args) {
        System.out.         


        

Answer 1

If you put the source in an appropriate directory hierarchy matching the package name (D:\javaTest\java\java\package1\App1.java), and compile/run from the root of the hierarchy (D:\javaTest), you wouldn't have this problem:

D:\javaTest>javac java\java\package1\App1.java

D:\javaTest>java java.java.package1.App1
App2 hello world...

You can also compile using the -d option so that the classes are moved into such a directory hierarchy:

javac -d . App2.java
java java.java.package1.App2

Note you shouldn't use a package name starting with java, and later versions of the JDK will throw a SecurityException. See this question for more information.