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eclipse Tips
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What is eclipse?
• Eclipse is a popular IDE (Integrated Development
Environment) that we will use to create, compile,
execute, and test our Java code.
• It has many advanced features that make it an
ideal tool not only for the academic setting but
also for the corporate world.
• We will be using only a small subset of its
capabilities. To learn more about eclipse, visit
their website at www.eclipse.org, or take
advantage of its extensive help features.
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Installing eclipse
• Note: You can skip this step on the school
computer, since Java and eclipse are already
installed on it
• Prerequisite for eclipse: Download the Java
Development Kit (JDK) if you don’t already have
it
– http://java.sun.com/javase/downloads/index.jsp
– Select JDK 6 Update 16 (listed under Java SE
Development Kit (JDK)
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Installing eclipse
(continued)
• Download eclipse (or copy it from the school’s S:
drive). Pick one of the 2 options below:
– To download:
• http://www.eclipse.org/downloads/
• Select Eclipse Classic 3.5.0 (there is an option for “Windows”
to the right of this option – select it if you have Windows)
– Or you can copy eclipse from the school’s shared drive:
• Copy folder S:\StudentShare\AP CS A\Eclipse to your flash
drive
• Copy the entire folder to your home PC
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Jar files
• Jar files are libraries that store compiled code that
you can use in your own programs.
• At school, copy the jar files to your H: drive. One
recommendation is to create a folder named
H:\JarFiles and copy any needed jar files to this
folder.
• Note: The KarelJRobot.jar file is located in folder
S:\StudentShare\AP CS A\Karel . You can copy
this file to H:\JarFiles for later use in programs.
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• workspace
– Projects
• Packages
workspace
– Classes
• A workspace is used to store all of your
Java classes.
• At school, create a workspace on your H:
drive. Do this by creating a new folder
named H:\workspace .
• To begin with, there should be no files in
this folder
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Launching eclipse
• To launch eclipse, select Start > Programs >
Student Applications > eclipse
• When you first open eclipse, it may ask you
to select the workspace. While at school,
select H:\workspace.
• If a Welcome screen appears, you can either
browse through some of the topics or close
it to get to the main eclipse windows.
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• workspace
– Projects
• Packages
Projects
– Classes
• A Java project contains source code and related files
for building a Java program. The Java project is a
folder underneath the workspace folder.
• To create a new Java Project:
–
–
–
–
Select File > New > Java Project
Enter the name of the project
All radio buttons should be on their top option
Remember to include the External jar file (listed under
the Libraries tab > Add External JARs). Note: While at
school, the jar file should be located on your H: drive
– Press “Finish”.
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• workspace
– Projects
• Packages
Packages
– Classes
• A Java package is used to organize related Java
classes. It is a folder underneath the Java project
folder.
• To create a new Java Package:
–
–
–
–
Single click on the project
Select File > New > Package
Enter the package name.
Press “Finish”.
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• workspace
– Projects
• Packages
Classes
– Classes
• A Java class is the programming code. The source
code has an extension of .java and is located in the
package folder. It is a text file and can be edited
with any text editor.
• To create a new Java class:
–
–
–
–
Single click on the package
Select File > New > Class
Enter the class name.
Press “Finish”.
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• workspace
– Projects
• Packages
Saving/Compiling/
Running a class
– Classes
• A class can always be saved, even if there are
errors. To do this, press the Save button.
• Saving the class will automatically try to compile
it. If it is free from errors, it will be compiled
successfully and a file with the extension .class
will be created in thhe package folder.
• To run a new Java class:
– Note: The class must have a main method to be run.
– Make the class the active class: Double click on it in
the Package explorer to make it active in the window.
– Select Run > Run as > Java application
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• workspace
– Projects
• Packages
– Classes
Proper
Indentation
• It is good practice to indent code so that a human
can more easily read it. The methods within a
class should be indented as well as the statements
within a method.
• Eclipse can help you with indentation:
– Show your class in the active window.
– Optionally, select the lines of code to be indented.
Otherwise, the entire class will be corrected.
– Select Source > Correct Indentation
– The end result is that your code should be indented
properly.
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Copying Classes between
School and Home
• Since there are times when you will want to continue your work at
home, you will need to be able to transfer your code back and forth.
This is where your flash drive becomes handy.
• To reduce confusion, keep the folder structure on your flash drive the
same as the folder structure on H:\workspace.
• Use file manager to locate the Java source file (that has extension
.java) within the package folder.
• Copy only the .java files (not the .class files) to your flash drive folder.
• You can then copy these files to your package folder on your
destination computer.
• Note: After you launch eclipse, it is important to refresh the
project and package. Otherwise, the new code may not be seen
within eclipse:
– Single click on the project and select File > Refresh (or press F5).
– Single click on the package and select File > Refresh (or press F5).
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