Recipe 3.3 Creating Java Packages

     

3.3.1 Problem

You want to put your code into a Java package.

3.3.2 Solution

Select File New Package, or right-click the Package Explorer in the Java perspective and select New Package. Alternatively, you can specify the package when you create a new class.

3.3.3 Discussion

In all but the most trivial projects, you usually put your Java code into a package. To create a new package, select a project in the Package Explorer and then select File New Package, or right-click the Package Explorer and select New Package. The New Java Package dialog appears, as shown in Figure 3-6. Enter the name of the new package, and click Finish. The new package will be added to the project in the Package Explorer.

Figure 3-6. Creating a new package

When the new package appears in the project, you can add classes to it by right-clicking it and selecting New Class.

Although you can create packages this way in Eclipse, usually you would create a package when you create a class (unless you're purposely breaking up your project into multiple package.) Recipe 3.4 covers the process of creating a package when creating a class.

When you access a class in another package, you must import it using that class's fully qualified name in your code:

   import org.cookbook.ch03.DisplayApp;   

 public class DisplayApp { public static void main(String[] args){ 

   DisplayApp display = new DisplayApp( );   

   display.print( );   

 } } 

Some code you want to work with might be in another project entirely. When you create a project, you can specify other projects you want included in the build path (see Recipe 3.4). Alternatively, in an existing project you can specify which other projects should be in the build path by selecting Project Properties Java Build Path.