My First Eclipse Experience.

This is a quick tutorial on how to get started with the Eclipse Integrated Development Environment (IDE. There are many Java IDEs, each with strengths and weaknesses. One of the strengths of Eclipse is that it is free! Another is that is has a market share of more than 50%, meaning that industrial users are finding it to be a good tool.

We will also use JCreator--free for the Learning Edition--which is very fast to launch, but which lacks some of the best features of the Professional Edition. (The Professional Edition is free for a 30-day trial.) I will use it in class sometimes. Another major player is NetBeans from Sun. There are technical and performance differences that make Eclipse preferable, I believe.

Eclipse can be thought of as a Java IDE, on top of which is built  IBM's WebSphere, a large collection of tools for building Web-based applications. By learning Eclipse you will be learning something of industrial strength that will also make learning WebSphere much faster if and when you get to that. IBM was a founding company of the Eclipse Foundation, which manages Eclipse. IBM is rather rapidly giving more parts of WebSphere to Eclipse; the entire package, with all updates, is now nearly 700MB. We will be using only a very small fraction of this functionality. I will give occasional demonstrations, of the "this-will-not-be-on-the-exam" type, of other things that can be done with Eclipse.

Of course Eclipse is much more than just a Java IDE. Tons of plugins are available, making it a highly flexible and powerful tool.

The Eclipse effort is open-source. I believe the organization has one paid employee, an executive director. All other work is done by volunteers; some key people are on loan from their employers to work  full-time on the project.

This presentation is entirely tied to my two sections of CSc 221, Software Design Lab, at City College of New York in Fall, 2005. Even more particularly, it is the technical part of what I did in the first lecture of the semester.

Steps in getting Eclipse from the course CD to your hard drive

At home . . .

  1. Create a folder named eclipse on your C drive. (In the 7/118 lab you can’t do this. Create a folder named eclipse in the temp folder and carry on. On your own computer, you can, of course, create a folder named eclipse on the C root.
  2. Insert the course CD into your CD drive. Copy the file eclipse-SDK-3.0.1-win32.zip into your eclipse folder.
  3. Unzip the file eclipse-SDK-3.0.1-win32.zip into the same folder. That will create another folder named eclipse containing the unzipped files and folders.
  4. You can launch Eclipse from this folder by double clicking on the file name eclipse.exe, or you can drag that file to your desktop or your quick launch bar, either of which will create a shortcut for you. This process will not put Eclipse into the Windows Registry. If you want--I neither favor nor advise against this--you can create a folder under Program Files named Eclipse and copy the Eclipse folder there. If you are using Linux, you will need to escape the space, writing #mkdir New\ Folder. (Thanks to David Gurvich for a correction on this.)
     

In the lab . . .

. . . you click on the Eclipse icon on the desktop. The only place that is writable by you is C:\temp, so you will  have to create a workspace (see below) there. On your own machine the workspace can be wherever you like. Make the appropriate changes in the instructions below, depending on whether you are in the lab or on your own machine.

Back to the tutorial . . .

  1. Open Eclipse: double click on the eclipse.exe file name, the Eclipse icon on the desktop, or whatever. When you are asked to select a workspace, browse to C:\temp. (When you are finished with this lab, you will be able to copy your workspace onto CD or floppy, ready to pick up at another session where you left off today.) After selecting a workspace, wait for Eclipse to launch.

(Actually, I'd suggest you first create a folder in C:\temp ( or wherever you want on your own machine) named 221HW1 or whatever, and specify that when you start Eclipse. Before long you are going to have lots of saved workspaces; put them somewhere you can find them, and give them names that mean something to you.)

  1. If this is the first time Eclipse has been opened with this workspace (it is), you will get a welcome screen. Roll over the icons in the middle and make a note that there are lots of help facilities available, but we don’t want that now. See Figures 1 and 2.

Figure 1.

Figure 2.

  1. After clicking on the arrow-like thing in the top right or the X in the top left, you will see a blank Eclipse workbench. See Figure 3.

Figure 3.

  1. Create a project: File/New/Project, or click on the New icon just below the File button and select Project. Name it Lab1, or anything else you please. Leave all checkboxes as they are. Click Finish. (You may be asked if you want to switch to a Java perspective. Say yes.)
  2. In the Package Explorer area on the left, your new project will appear. Click on the + to expand the view. You will see that some libraries have been made available automatically. NOTE: we want jre1.5.0_04. If that is not what you see, plunge ahead bravely. That is what is installed in the lab, and that is what is on the course CD.
  3. Right click on the Lab1 project symbol and choose New/Package. Name it helloJava, or anything else you please. If you start with an uppercase letter you will be told that the convention is for package names to begin with a lowercase letter. This is only a convention, but why not do it the standard way? Virtually everybody does.
  4. Right click on the package and select New/Class. Name it MyFirstEclipse, or whatever you please. Unclick Inherited Abstract Methods, and click public static void main. The only modifier you want is public. Click Finish. When you are ready to click Finish, the dialog should look like Figure 4.

Figure 4.

  1. (If you are like me, you will have trouble remembering, at the beginning, which comes first: Project or Package? There are four things you need; try memorizing the phrase "Workspace ProPack Class." Crazy? Worked for me.)
  2. The editor window will show a basic Java program with a main method. Your workbench will look like Figure 5. Experiment with dragging the boundaries between panes on this window to make the panes larger or smaller. The comments that begin with /** are Javadoc comments. We will talk about these later. For now, you can either ignore them or erase them. What you see will not exactly match what is shown in Figure 5.

Figure 5.

 

  1. Modify

public static void main(String[] args) {

    }

    to:

public static void main(String[] args) {

    System.out.println("Hello, Eclipse World!");

}

 

(If the string "Hello . . .." extends over two lines in your browser, be aware that in the program, as I ran it, that didn't happen. Strings in Java cannot be broken across lines.)

  1. Click Window/Show View/Console. A console window will open at the bottom, with other views available on tabs. (If a Console tab is already there, just click on it.)
  2. If no funny red marks show in the left margin, your program is syntactically correct: Eclipse has been compiling it as you type. Make that official by doing a Save (Control+S is faster). If a red circle with an X in it appears, click on the Problems tab at the bottom to see what the problem(s) is/are. In fact, make some deliberate errors so you can see this. Then fix it and save again. Click on the Console tab.
  1. Click Run/Run as/Java Application, and your output will appear in the Console window.
  2. Make some small change and press Control + F11, which means "Run the last thing I ran." Or click on the icon near the top left that looks like this: .
  3. If you try to run without saving, a dialog box will appear asking you what to save. You can just click OK. Or, dismiss the dialog, Save, and say to run again.
  4. Take out the statement to print Hello Eclipse etc.
  5. Insert a declaration at the class level and within main and add statements as follows. (We’ll worry later about that static, and don’t worry about the indentation differences. ) Fix any syntactic errors, Save, and run. The sum of the first ten integers is 55. (I’ll bet you knew that.)

    public class MyFirstEclipse {

        static int sum;

        public static void main(String[] args) {

            for (int i = 1; i <= 10; i++)

                sum += i;

            System.out.print("The sum of the first 10 integers is: " + sum);

        }

    }

    (See comment above about the System.out.println statement. Strings cannot be broken across lines.)

  1. Now let’s move to HW1. From the course CD, copy the file HW1StarterV3.java to C:\temp. (Or wherever, on your machine.)
  2. Back in Eclipse, right click on your package and select Import.
  3. Select File System and browse to C:\temp. Click OK.
  4. You will see your HW1StarterV3.java file. Check that box and click Finish.
  5. Click on the + to the left of your project name. Your HW1 class is there. Double click on its symbol to open it in the editor window.
  6. You will get a nasty message saying that the package isn’t what Eclipse expected. Right click on the red error indicator at the top and select Quick Fix. (Eclipse knows what to do; it just wants you to admit how smart it is. Well, not really; you might not want the automatic correction.) Click on Add package declaration . . . An import with the package name is inserted.
    NOTE: In some cases, for unknown reasons, Quick Fix doesn't pop up. Assuming you named your package hw1, insert the following lines, before any of the import statements:
    package hw1;
  7. Save the file to formalize the compilation (which has already been done). Don’t look for a Compile button! There isn’t one.
  8. Do Run/Run as/Java Application. The GUI created by the program will appear.
  9. To exercise the GUI, you need to resize the Eclipse window so that you can see the GUI and the Eclipse Console. Play with it. Does it complain if you hit Enter with no first name? (It better!)

That's it for this lesson. This is how far we got on the first day. Specifically, we did not discuss the Java concepts at all, and did not examine the HW1 program.

Whenever you are ready to leave the lab, close Eclipse and send yourself and your partner email with your Java file attached. Or copy to a USB memory thing, or burn a CD. But email is simplest.

To continue, go to  Instructions and code snippets for the second lab.

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