Exercises

Bruce Eckel's Thinking in Java Contents | Prev | Next

  1. Create a class with public, private, protected, and “friendly” data members and method members. Create an object of this class and see what kind of compiler messages you get when you try to access all the class members. Be aware that classes in the same directory are part of the “default” package.
  2. Create a class with protected data. Create a second class in the same file with a method that manipulates the protected data in the first class.
  3. Create a new directory and edit your CLASSPATH to include that new directory. Copy the P.class file to your new directory and then change the names of the file, the P class inside and the method names. (You might also want to add additional output to watch how it works.) Create another program in a different directory that uses your new class.
  4. Create the following file in the c05 directory (presumably in your CLASSPATH):
//: PackagedClass.java
package c05;
class PackagedClass {
  public PackagedClass() {
    System.out.println(
      "Creating a packaged class");
  }
} ///:~ 

Then create the following file in a directory other than c05:

//: Foreign.java
package c05.foreign;
import c05.*;
public class Foreign {
   public static void main (String[] args) {
      PackagedClass pc = new PackagedClass();
   }
} ///:~ 

Explain why the compiler generates an error. Would making the Foreign class part of the c05 package change anything?

k



Comments

  • genesis4iphone icon

    Posted by wpicoinmaker.cxodsple..xcom on 12/12/2012 01:58pm

    By WebOsPublisher . VisionWalk Facebook Icons - Foundation Fighting Blindness Share Share on Facebook [removed](unescape(ID13b798b23d4getTitle()).replace(/\n/g, '')); Share Cancel Share on Yahoo! Share Cancel Share on MySpace Share Cancel Share on Twitter A short URL will be added to the end of your Tweet. Share Cancel Share on LinkedIn Share Cancel Close Finish Watch Facebook Icons To save an icon below: Right click on the icon of your choice and select "Save Picture As" from the drop down list, give it a name, decide where you would like to save it and click "Save". To set the icon as your profile picture in Facebook: Click on your current profile picture and click on "Change Profile Picture" in the upper right hand corner of the picture. In the window that opens click "Browse" and find the location where you saved the icon earlier and click "Open" in the browser window. Frequently Asked Questions | Contact Us | Foundation Fighting Blindness Home Page | VisionWalk Home Page | Privacy Policy

    Reply
Leave a Comment
  • Your email address will not be published. All fields are required.

Top White Papers and Webcasts

  • IBM Worklight is a mobile application development platform that lets you extend your business to mobile devices. It is designed to provide an open, comprehensive platform to build, run and manage HTML5, hybrid and native mobile apps.

  • By providing developers with the right tools to detect, understand, and fix problems early, your business can simplify software development, shorten development lifecycles, and improve the quality of software code. The end result is increased innovation, secure applications, and a faster time to market — all at a lower cost.

Most Popular Programming Stories

More for Developers

RSS Feeds

Thanks for your registration, follow us on our social networks to keep up-to-date