Java™ Application Development on Linux - Dator

118Chapter 5The Sun Microsystems Java Software <strong>Development</strong> KitExample 5.2 Compiling FetchURL.java with the -verbose option$ javac -verbose FetchURL.java[parsing started FetchURL.java][parsing completed 479ms][loading /usr/java/j2sdk1.4.1_02/jre/lib/rt.jar(java/lang/Object.class)][loading /usr/java/j2sdk1.4.1_02/jre/lib/rt.jar(java/net/URL.class)][loading /usr/java/j2sdk1.4.1_02/jre/lib/rt.jar(java/lang/String.class)][checking FetchURL][loading /usr/java/j2sdk1.4.1_02/jre/lib/rt.jar(java/lang/Exception.class)][loading /usr/java/j2sdk1.4.1_02/jre/lib/rt.jar(java/lang/Throwable.class)][loading /usr/java/j2sdk1.4.1_02/jre/lib/rt.jar(java/io/BufferedReader.class)][loading /usr/java/j2sdk1.4.1_02/jre/lib/rt.jar(java/io/InputStreamReader.class)][loading /usr/java/j2sdk1.4.1_02/jre/lib/rt.jar(java/net/URLConnection.class)][loading /usr/java/j2sdk1.4.1_02/jre/lib/rt.jar(java/io/Reader.class)][loading /usr/java/j2sdk1.4.1_02/jre/lib/rt.jar(java/io/InputStream.class)][loading /usr/java/j2sdk1.4.1_02/jre/lib/rt.jar(java/lang/System.class)][loading /usr/java/j2sdk1.4.1_02/jre/lib/rt.jar(java/io/PrintStream.class)][loading /usr/java/j2sdk1.4.1_02/jre/lib/rt.jar(java/io/FilterOutputStream.class)][loading /usr/java/j2sdk1.4.1_02/jre/lib/rt.jar(java/io/OutputStream.class)][loading /usr/java/j2sdk1.4.1_02/jre/lib/rt.jar(java/lang/Error.class)][loading /usr/java/j2sdk1.4.1_02/jre/lib/rt.jar(java/net/MalformedURLException.class)][loading /usr/java/j2sdk1.4.1_02/jre/lib/rt.jar(java/io/IOException.class)][loading /usr/java/j2sdk1.4.1_02/jre/lib/rt.jar(java/lang/RuntimeException.class)][loading /usr/java/j2sdk1.4.1_02/jre/lib/rt.jar(java/lang/StringBuffer.class)][wrote FetchURL.class][total 3469ms]$the application, either directly through composition or inheritance, or indirectlybecause the classes we used are themselves composed of or inherit from otherclasses. How did the Java compiler know where to find these classes? For this,it used what the Sun documentation calls a bootstrap classpath, which is set whenthe SDK is installed. A classpath is a list of directories and/or JAR files that aresearched for classes. We seem to dimly recall that in early versions of Java, therewas only one classpath, and if you changed it, you had to remember to put theJava runtime JAR file on it, or none of the standard APIs were available. This,no doubt, is why Sun created the concept of a bootstrap classpath. If you useany third party JAR files or you create your own, you must tell the compilerabout it by creating your own classpath.There are two ways to provide a classpath to the Java compiler. One isthrough a command-line switch, which we will cover in a moment. The otheris through an environment variable. The CLASSPATH environment variable lists