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Financial : Although the Connexions site makes it possible for you to download a PDF file for thismodule at no charge, and also makes it possible for you to purchase a pre-printed version of the PDF file, you should beaware that some 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.com showing me as the author. Ineither receive compensation for those sales nor do I know who does receive compensation. If you purchase such a book, please beaware that it is a copy of a module that is freely available on cnx.org and that it was made and published withoutmy prior knowledge.
Affiliation : I am a professor of Computer Information Technology at Austin Community College in Austin, TX.
A complete listing of the program follows.
Listing 1 . Source code for FirstProgram.
/* Begin block comment
This is the beginning of a block comment in Java.Everything in this block comment is for human consumption
and will be ignored by the Java compiler.File: FirstProgram.java
Copyright 2012, R.G. BaldwinThis program is designed to illustrate the most common
forms of the three pillars of procedural programming inJava code:
sequenceselection
loopThe program also illustrates calling a method, passing
a parameter to the method, and receiving a returnedvalue from the method.
Assuming that the Java Development Kit (JDK) is properlyinstalled on your computer, do the following to compile
and run this program.1. Copy this program into a file named FirstProgram.java
and store the file in a folder on your disk.2. Open a command-line window in the folder containing
the file.3. Type the following command to compile the program:
javac FirstProgram.java4.4. Type the following command to run the program:
java FirstProgramAny text that begins with // in the following program
code is a comment. The compiler will ignore everythingfrom the // to the end of the line.
The compiler also ignores blank lines.Note that this program was designed to illustrate the
concepts while being as non-cryptic as possible.The program should display the following text on the
screen except that the time will be different each timethat you run the program.
value in = 5Odd time = 1353849164875
countA = 0countA = 1
countA = 2countB = 0
countB = 1countB = 2
value out = 10End block comment ***************************************/
//The actual program begins with the next line.import java.util.*;
class FirstProgram{//The program consists of a sequence of statements.//The next statement is the beginning of the main
// method, which is required in all Java applications.public static void main(String[] args){//Program execution begins here.//Declare and initialize a variable.
int var = 5;//Statements of the following type display// information on the screen
System.out.println("value in = " + var);//Call a method and pass a parameter to the method.//Save the returned value in var, replacing what
// was previously stored there.//Control is passed to the method named firstMethod.
var = firstMethod(var);//Control has returned from the method named
// firstMethod.System.out.println("value out = " + var);//Program execution ends here
}//end main method/****visual separator comment**************************/public static int firstMethod(int inData){//Control is now in this method.//Illustrate selection
//Get the elapsed time in milliseconds since Jan 1970.long time = new Date().getTime();//Select even or odd time and display the results
if(time % 2 == 0){System.out.println("Even time = " + time);
}else{System.out.println("Odd time = " + time);
}//end if-else selection//Illustrate a while loopint countA = 0;
while(countA<3){
System.out.println("countA = " + countA);//Increment the counter
countA = countA + 1;}//end while loop//Illustrate a for loop
for(int countB = 0; countB<3; countB = countB + 1){
System.out.println("countB = " + countB);}//end for loop//Illustrate returning a value from a method and
// returning control back to the calling method.return 2*inData;
}//end firstMethod}//end class FirstProgram//The program ends with the previous line.
-end-
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