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

  • Live Event Date: March 19, 2015 @ 1:00 p.m. ET / 10:00 a.m. PT The 2015 Enterprise Mobile Application Survey asked 250 mobility professionals what their biggest mobile challenges are, how many employees they are equipping with mobile apps, and their methods for driving value with mobility. Join Dan Woods, Editor and CTO of CITO Research, and Alan Murray, SVP of Products at Apperian, as they break down the results of this survey and discuss how enterprises are using mobile application management and private …

  • On-demand Event Event Date: February 12, 2015 The evolution of systems engineering with the SysML modeling language has resulted in improved requirements specification, better architectural definition, and better hand-off to downstream engineering. Agile methods have proven successful in the software domain, but how can these methods be applied to systems engineering? Check out this webcast and join Bruce Powel Douglass, author of Real-Time Agility, as he discusses how agile methods have had a tremendous …

Most Popular Programming Stories

More for Developers

RSS Feeds

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