CMSC 341

1. CMSC 341 CVS/Ant Java Packages Ant CVS Project Submission CMSC 341

2. CMSC 341 CVS/Ant Packages • Java packages create libraries • A group of classes organized together into a single namespace. • Allows multiple classes with the same name • MyPackage.Stack • YourPackage.Stack

3. CMSC 341 CVS/Ant Packages • A file may belong to only one package. • Packages serve as a namespace in Java and create a directory hierarchy when compiled. • Classes are placed in a package using the following syntax in the first line that is not a comment. • package packagename; • package packagename.subpackagename;

4. CMSC 341 CVS/Ant Multiple Stack Classes • // My stack.java file • package MyPackage; • public class Stack • { • // … • }; // Your stack.java file package YourPackage; public class Stack { // … };

5. CMSC 341 CVS/Ant Packages (cont.) • The fully qualified name of a class is the packageName.ClassName. • java.lang.String • MyPackage.Stack • YourPackage.Stack • To alleviate the burden of using the fully qualified name of a class, use an import statement before the class declaration. • import java.util.StringBuffer; • import java.util.*; • import MyPackage.Stack; • import YourPackage.*;

6. CMSC 341 CVS/Ant Project1 Root of project directory tree src proj1 Package name Example.java bin Package name proj1 Example.class Packages (cont.) • It is common practice to duplicate the package directory hierarchy in a directory named src and to compile to a directory named bin. • Create this directory manually in your GL account • Eclipse creates this directory structure for you

7. CMSC 341 CVS/Ant Compiling with packages • When using the Unix command line, classes in a package are compiled using the –d option. • Given the directory structure on the previous slide, run the command below from the src directory to compile the code from the Project1/src directory to the Project1/bin directory. • The -d switch tells the compiler where to place the .class file • The bin directory must exist before compiling. The compiler will create the proj1 directory under bin. javac –d ../bin proj1/Example.java

8. CMSC 341 CVS/Ant Packages and Eclipse • By default Eclipse automatically creates a src/ directory when you create a new Java Project • Eclipse will then automatically create a bin/ directory and associated package directory hierarchy when it compiles your Java classes • Note: the bin/ directory tree is hidden by Eclipse when in the Java perspective, but you can see it if viewing the file system.

9. CMSC 341 CVS/Ant What is Ant? Ant is a Java based tool for automating the build process Platform independent commands (works on Windows, Mac & Unix) XML based format Easily extendable using Java classes Ant is an open source (free) Apache project Ant files used in this course require the package directory structure described earlier

10. CMSC 341 CVS/Ant Anatomy of a Build File Ant’s build files are written in XML Convention is to call file build.xml Each build file contains A project At least 1 target Targets are composed of some number of tasks Build files may also contain properties Like macros in a make file Comments are within <!-- --> blocks

11. CMSC 341 CVS/Ant Projects The project tag is used to define the project to which the ANT file applies Projects tags typically contain 3 attributes name – a logical name for the project default – the default target to execute basedir – the base directory relative to which all operations are performed Additionally, a description for the project can be specified from within the project tag

12. CMSC 341 CVS/Ant Project tag <project name="Sample Project" default="compile" basedir="."> <description> A sample build file for this project Recall that “.” (dot) refers to the current directory </description> </project>

13. CMSC 341 CVS/Ant Properties Build files may contain constants (known as properties) to assign a value to a variable which can then be used throughout the project Makes maintaining large build files more manageable and easily changeable Projects can have a set of properties Property tags consist of a name/value pair Use the property names throughout the build file The value is substituted for the name when the build file is “executed”

14. CMSC 341 CVS/Ant Build File with Properties <project name="Sample Project" default="compile" basedir="."> <description> A sample build file for this project </description> <!-- global properties (constants) for this build file --> <property name="source.dir" location="src"/> <property name="build.dir" location="bin"/> <property name="doc.dir" location="doc"/> </project>

15. CMSC 341 CVS/Ant Tasks A task represents an action that needs execution Tasks have a variable number of attributes which are task dependant There are a number of built-in tasks, most of which are things which you would typically do as part of a build process mkdir - create a directory javac - compile java source code java - execute a Java .class file javadoc - run the javadoc tool over some files And many, many others… For a full list see: http://ant.apache.org/manual/tasksoverview.html

16. CMSC 341 CVS/Ant Targets The target tag has the following required attribute name – the logical name for a target Targets may also have optional attributes such as depends – a list of other target names for which this task is dependant upon, the specified task(s) get executed first description – a description of what a target does Targets in Ant can depend on some number of other targets For example, we might have a target to create a jarfile, which first depends upon another target to compile the code Targets contain a list of tasks to be executed

17. CMSC 341 CVS/Ant Build File with Targets <project name="Sample Project" default="compile" basedir="."> <!-- set up some directories used by this project --> <target name="init" description="setup project directories"> <!-- list of tasks to be executed --> </target> <!-- Compile the java code in src dir into build dir --> <target name="compile" depends="init" description="compile java sources"> <!-- list of tasks to be executed --> </target> <!-- Generate javadocs for current project into docs dir --> <target name="doc" depends="init" description="generate documentation"> <!-- list of tasks to be executed --> </target> <!-- Execute main in the specified class under ${build.dir} --> <target name=”run" depends=“compile” description=”run the application"> <!-- list of tasks to be executed --> </target> <!-- Delete the build & doc directories and Emacs backup (*~) files --> <target name="clean" description="tidy up the workspace"> <!-- list of tasks to be executed --> </target> </project>

18. CMSC 341 CVS/Ant Initialization Target & Tasks Our initialization target creates the build and documentation directories The mkdir task creates a directory <project name="Sample Project" default="compile" basedir="."> ... <!-- set up some directories used by this project --> <target name="init" description="setup project directories"> <mkdir dir="${build.dir}"/> <mkdir dir="${doc.dir}"/> </target> ... </project>

19. CMSC 341 CVS/Ant Compilation Target & Tasks Our compilation target will compile all java files in the source directory The javac task compiles sources into classes Note the dependence on the init task <project name="Sample Project" default="compile" basedir="."> ... <!-- Compile the java code in ${src.dir} into ${build.dir} --> <target name="compile" depends="init" description="compile java sources"> <javac srcdir="${source.dir}" destdir="${build.dir}"/> </target> ... </project>

20. Run Target & Tasks • Our run target will execute main in the fully specified class • Typically dependent on the compile task <project name="Sample Project" default="compile" basedir="."> ... <!-- Execute main in the fully qualified name under ${build.dir} --> <target name=”run" depends=”compile" description=“run the application"> <java directory=“${build.dir}” classname=“${main.class}” fork=“yes”> <arg line=“${args}” /> </java> </target> ... </project> July 2011 20 CMSC 341 CVS/Ant

21. CMSC 341 CVS/Ant Running Ant – Command Line Move into the directory which contains the build.xml file Type ant followed by the name of a target unix> ant run unix> ant compile Type ant at the unix prompt to run the project’s default target -- see screen shot on next page unix> ant

22. CMSC 341 CVS/Ant Ant screen snapshot

23. CMSC 341 CVS/Ant Project Submission • Projects in this course will be submitted electronically through the use of an industry standard version control system named CVS. • CVS can be used from the Unix command line, or from an Eclipse perspective. • In either case, we must be familiar with Java packages and their associated directory structure as discussed earlier.

24. CMSC 341 CVS/Ant What is CVS? Concurrent Versioning System (CVS) is one of the earlier SCM systems which gained wide adoption Open source Easy to install and use Simple command line client Wide integration in a lot of development tools Used for submitting projects in this course For good introduction on version control and CVS see the following book… Pragmatic Version Control using CVS

25. CMSC 341 CVS/Ant CVS Terminology Repository – the place where resources (files) are stored Checkout – copy resources from the repository and create a working copy Checkin/Commit – place resources from your working copy into the repository Add – place a resource under version control Remove – delete a resource from version control Update – pull down changes from the repository into your working copy

26. CMSC 341 CVS/Ant Using CVS in this course • See http://www.cs.umbc.edu/courses/undergraduate/341/fall12/projects/CVS.html • For additional slides about CVS submission via Eclipse: • http://www.cs.umbc.edu/courses/undergraduate/341/Lectures/CVS/intro-to-cvs.ppt