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Reusing the methods
The purpose of the code fragment in Listing 4 is to illustrate the reusable nature of methods.
| Listing 4 . Calling the same methods again. |
|---|
double peas;
peas = 36.;double sqRtPeas = Math.sqrt(peas);
System.out.println(sqRtPeas); |
The code in this fragment calls the same sqrt method that was called before. In this case, the method is called to calculate thesquare root of the value stored in the variable named peas instead of the value stored in the variable named beans .
This fragment saves the value returned from the sqrt method in a new variable named sqRtPeas . Then the fragment calls the same println method as before to display the value now stored in the variable named sqRtPeas .
Write once and use over and over
Methods make it possible to write some code once and then use that code many times in the same program. This is the opposite of in-line code , which requires you to write essentially the same code multiple times in order to accomplish the same purpose more than once in a program.
I encourage you to run the program that I presented in this lesson to confirm that you get the same results. Experiment withthe code, making changes, and observing the results of your changes. Make certain that you can explain why your changes behave as they do.
Listing 5 is a complete listing of the program named SqRt01 .
| Listing 5 . The program named SqRt01. |
|---|
//File SqRt01.java
class SqRt01 {public static void main(String[] args){double beans;
beans = 25.5;double sqRtBns = Math.sqrt(beans);
System.out.println(sqRtBns);double peas;
peas = 36.;double sqRtPeas = Math.sqrt(peas);
System.out.println(sqRtPeas);}//end main
}//End SqRt01 class |
Listing 6 contains the commands for a batch file that can be used to compile and run the program named SqRt01 .
| Listing 6 . A batch file for compiling and running the program named SqRt01. |
|---|
echo off
clsdel *.class
javac -cp .; SqRt01.javajava -cp .; SqRt01
pause |
This section contains a variety of miscellaneous information.
Financial : Although the Connexions site makes it possible for you to download a PDFfile for this module at no charge, and also makes it possible for you to purchase a pre-printed version of the PDF file, you should be aware thatsome of the HTML elements in this module may not translate well into PDF.
I also want you to know that, I receive no financial compensation from the Connexions website even if you purchase the PDF version of the module.
In the past, unknown individuals have copied my modules from cnx.org, converted them to Kindle books, and placed them for sale on Amazon.comshowing me as the author. I neither receive compensation for those sales nor do I know who does receive compensation. If you purchase such a book, pleasebe aware that it is a copy of a module that is freely available on cnx.org and that it was made and published without my prior knowledge.
Affiliation : I am a professor of Computer Information Technology at Austin Community College in Austin, TX.
-end-
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