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Packages, javac, java, javadoc

Packages, javac, java, javadoc. In moderately big programs packages are essential Can’t easily live in a directory with 50 .java files Can’t easily co-exist in such a directory Harder to use tools like Make and Ant

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Packages, javac, java, javadoc

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  1. Packages, javac, java, javadoc • In moderately big programs packages are essential • Can’t easily live in a directory with 50 .java files • Can’t easily co-exist in such a directory • Harder to use tools like Make and Ant • Java packages correspond semantically to modules (related classes) and syntactically to a directory structure • Class names correspond to file names • Package names correspond to directories • Each of javac, java, javadoc is slightly different with packages • File system vs. compiler vs. runtime

  2. CLASSPATH and related concepts • The default CLASSPATH is . current directory • Works fine with default/unnamed packages • Will not work with named packages • Set CLASSPATH to directory in which packages live also include current dir • setenv CLASSPATH "~ola:." • setenv CLASSPATH "`pwd`:." • On windows machines change environment variable • 'ls' should show, e.g., elan (which has parser, instruction, and so on, see the elan example)

  3. More package details • To compile • Can cd into directory and type javac *.java • Can also type javac elan/*.java from one level up • If CLASSPATH isn't set, the second won't work • To run • java elan.parser.ElanParser will work, you must specify the "real" name of the class being used. • Reading files requires full-paths or run from directory in which file lives • To document • http://java.sun.com/j2se/javadoc/faq.html • Don't need to use –sourcepath, but can • javadoc –d doc elan elan.parser elan.instruction …

  4. Elan parsing • Packages separate concepts and concerns • expression is just for standard infix expressions • Like the BNF example from jelan/simple • instruction is for programming constructs, e.g., repeat • See Instruction, RepeatInstruction, and SILInstruction • Each sub-package must import other packages • Problem? Depends on point-of-view • Adding a new language feature, e.g., IF statement • IfToken added in elan/parser/token • IfParser added in elan/parser • If instruction added in elan/instruction, returned by parser • If added to instructions.prop

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