Computer Science 209 Software Development Packages

What Is a Package? A package organizes related resources (interfaces and classes) into a conceptual unit Like a module in other languages Examples: –java.lang (basic Java resources) –java.util (collections, I/O resources, random numbers) –javax.swing, java.awt (GUIs) –newutil – resources for true stacks, etc.

Using a Package import java.util.*; import newutil.TrueStack; import newutil.ArrayStack; import newutil.LinkedStack; public class TestStack{ public static void main(String[] args){ // Blah blah blah }

Defining a Package package newutil; import java.util.Collection; public interface TrueStack extends Collection { // Blah blah blah } package newutil; import java.util.*; public class AbstractStack extends AbstractCollection implements TrueSTack { // Blah blah blah }

File Organization Source files for classes should be in a directory whose name is the package name When byte code is generated, it is placed in a directory with the package’s name These directories should be just below the directories of the source or byte code files that use them

File Organization truestack2 TestStack.java newutil TrueStack.java AbstractStack.java ArrayStack.java LinkedStack.java

Creating a Package from the Terminal Place the.java files in a directory whose name is the package name Attach to this directory and run javac *.java Place the package directory in the directory where your client program will be Run javac or java from this directory as needed