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copied!<p>These examples assume the following source structure:</p> <pre><code>C:\temp\compile-test\src\a\b\c\D.java </code></pre> <p>Where D.java is:</p> <pre><code>package a.b.c; public class D { } </code></pre> <p>The first problem, <strong>cannot read: myfile.java</strong>, is because it is not correct to use the <strong><code>cp</code></strong> command line option to point to your source code.</p> <pre><code>C:\temp\compile-test\src>javac -cp c:\temp\compile-test\src\a\b\c D.java javac: file not found: D.java Usage: javac <options> <source files> use -help for a list of possible options </code></pre> <p>This should instead be the following, where <code>javac</code> is run from your source folder, and we can use relative paths to the source files (NOTE - <code>javac</code> is run from the source folder here):</p> <pre><code>C:\temp\compile-test\src>javac a\b\c\D.java </code></pre> <p>Or this, where we specify full paths to the source files, and <code>javac</code> can be run from anywhere (NOTE - <code>javac</code> is run from <code>C:\</code> here):</p> <pre><code>C:\>javac temp\compile-test\src\a\b\c\D.java </code></pre> <p>Both of the above options will result in your class files being created in the same folder as the source. I.e.:</p> <pre><code>C:\temp\compile-test\src\a\b\c\D.class </code></pre> <p>For the second problem, if you try and run a class that has a package name from 'inside' the package, this will result in the name being wrong (NOTE - <code>java</code> being run from 'inside' the package here):</p> <pre><code>C:\temp\compile-test\src\a\b\c>java D Exception in thread "main" java.lang.NoClassDefFoundError: D (wrong name: a/b/c/D) at java.lang.ClassLoader.defineClass1(Native Method) at java.lang.ClassLoader.defineClassCond(ClassLoader.java:631) at java.lang.ClassLoader.defineClass(ClassLoader.java:615) at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:141) at java.net.URLClassLoader.defineClass(URLClassLoader.java:283) at java.net.URLClassLoader.access$000(URLClassLoader.java:58) at java.net.URLClassLoader$1.run(URLClassLoader.java:197) at java.security.AccessController.doPrivileged(Native Method) at java.net.URLClassLoader.findClass(URLClassLoader.java:190) at java.lang.ClassLoader.loadClass(ClassLoader.java:306) at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301) at java.lang.ClassLoader.loadClass(ClassLoader.java:247) Could not find the main class: D. Program will exit. </code></pre> <p>To run the <code>D</code> class, you should be at the package 'root', and supply the <a href="http://docs.oracle.com/javase/1.5.0/docs/api/java/lang/Class.html#getName%28%29" rel="noreferrer">Fully Qualified Class Name</a>. I.e.:</p> <pre><code>C:\temp\compile-test\src>java a.b.c.D Exception in thread "main" java.lang.NoSuchMethodError: main </code></pre> <p>Note I get an exception as the <code>D</code> class doesn't have a main method, and so cannot be run. To fix, we add a main method:</p> <pre><code>package a.b.c; public class D { public static void main(String[] args) { System.out.println("main"); } } </code></pre> <p>and re-run:</p> <pre><code>C:\temp\compile-test\src>java a.b.c.D main </code></pre>

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