Lecture Notes CS 101 from 9/2/2010

INtro to Java Programming Elements

Steps to writing a Java Program

1.  Edit the Source code file
2.  Run the Java Compiler to translate the
      Source Code File to an "Executable File"
      which is a file that the computer can
      run.
3.  Run the Executable File

Two primary classifications of Errors when
  writing a program.

1.  Syntax Error - program is not written
                   using proper "punctution"
2.  Logic Error - program does not perform
                  as desired


Elements in a Java Program

Comments - items placed in a program for
           the human readers/writer to look
           at.   This information is ignored
           by the compiler.  This information 
           is normally used to briefly describe
           what the program is attempting to
           do.

   End of Line Comment   //  

   Block Comments  Start with a /*
                   End with a   */


Class Name - The name of the file must
     match the name of the public class in
     that file

Output statement - can come in many forms
     one form is the System.out.println()
     method.  The information contained 
     between the parentheses is displayed
     in the console window as output.

Variables - words that identify "mailboxes"
            in memory.  The words must start
            with a letter and then can contain
            letters, digits or the underscore
            character
   Valid Variable names: index, value1, i,
                         helloThere, maxValue,
                         here_is_another_variable,
                         sdfsd, average, a1b2c3

   invalid variable name: 23rdValue, value^%$

   variable are created with a 
        variable declaration statement

       int value1;
       int value2, value3;
       int value4 = 0;
   
   General Syntax:  
        <type> <variableName> ;

Assignment statements - allow a value in a
         variable to be changed.

   General Syntax: 
        <variableName> = <expression> ;

        value1 = 35;
        value2 = 10 * 3;
        value3 = value1;
        value4 = value3 + 8;