Java™ Application Development on Linux - Dator

5.3 The Java Compiler119Example 5.3 Setting the CLASSPATH environment variable$ export CLASSPATH=/home/mschwarz/java/simpleApp:/var/java/lib/project.jar$ echo $CLASSPATH/home/mschwarz/java/simpleApp:/var/java/lib/project.jar$directories and/or JAR or ZIP files that contain classes. Each directory or JARfile is separated from the others by a colon (“:”), as shown in Example 5.3.The classpath for the compiler consists of the bootstrap classpath plus theuser-specified classpath. What does the classpath mean in terms of Java classnames? Think of the classpath as a list of “package roots.” In otherwords, when you refer to a class like java.sql.DriverManager ornet.multitool.SAMoney, the Java compiler is going to go to eachentry in the combined bootstrap-and-user classpath and check there forjava/sql/DriverManager.class or net/multitool/SAMoney.class. Ifit doesn’t find the .class file in a candidate directory, it will look for the.java file. If it finds the .java file, it will compile it and then use the resulting.class file. When it has a .class file for the class, it stops searching theclasspath. In this way, compiling the single “main” class of an application willoften compile the whole application (we will get to exceptions to that rule later).5.3.2 javac OptionsThe Java compiler has many command-line options that modify its behavior.We will go over the most important ones here. This is not a complete reference!See the Sun SDK Documentation for complete reference information.-classpathSets the classpath. This overrides the CLASSPATH environment variable, ifone is specified.-dThis switch is followed by a directory name. Compiled classes are placedin that directory. Normally, compiled classes are placed in the samedirectory as the source code.