Java1468-plotting engineering and scientific data using java  (Page 4/25)

In the case of Figure 2 , the origin was moved to the left, the total expanse of the horizontal axis was increased, and the space between the tic marks on thevertical axis was increased from 20 units to 50 units.

(It will help you to see the differences if you will position two browser windows side-by-side while viewing one display in one browser windowand viewing the other display in the other browser window.)

Discussion and sample code

Testing the plotting program

I am assuming that you have accomplished the minimal steps required to get the Java Development Kit (JDK) that is available from Oracle installed on your computer

To run the plotting program named Graph01 in self-test mode, do the following:

• Copy the code in Listing 39 into a file named Graph01.java .
• Copy the code in Listing 1 into a file named GraphIntfc.java , and put that file in the same directory as the file named Graph01.java above.
• Compile the program named Graph01.java using the Java Development Kit (JDK) . (Note, you must be using Java Standard Edition (SE) version 1.4 or later. On the date of this module update, JavaSE 8u60 is the latest released version.)

At this point, you should be able to execute the program named Graph01 in self-test mode by entering the following command at the command prompt in the same directory where you compiled the program:

If everything has been done correctly up to this point, a display similar to that shown in Figure 4 should appear on your screen. (Note that you may need to match up the parameter values in the text fields at the bottom of the frameand click the Graph button to cause the two displays to match exactly.)

Using the plotting program

To use the plotting program with your own data generator program, do the following:

• Still working in the same directory, define and compile a data generator class that implements the interface named GraphIntfc01 , shown in Listing 1 .
• Start the plotting program named Graph01 running by following the instructions that I will provide below.

Plotting your data using Graph01

Assume that your data-generator class is named MyData , and that you have successfully compiled it in the same directory as the compiledversion of Graph01.

The next step is to enter the following command at the command prompt in the same directory. (Note that this command differs from the command given earlier. This command provides the name of your class as a command-line argument following the name of the plotting program.)

When you do this, the plotting program should start pulling the necessary data from your data-generator program and plotting that data in the format shownin Figure 1 .

Modifying plotting parameters

Once all the curves have been plotted, you can change any of the plotting parameter values in the text fields at the bottom of the display and press thebutton labeled Graph . When you press the button, the plotting program will re-plot your data using the new plotting parameters.

The plotting parameters

Here is the meaning of the plotting-parameter text fields shown in Figure 1 :