Class 09-22 Notes CS 107
Wednesday, September 22, 2010 11:59 AM
Announcements: - You'll be glad you came to class today... - For midterm #1 in lab, you need to know how to write a program that manipulates characters on an input line. We'll do an example in class today.
/** * I/O > Console I/O > ConsoleIOScanner.java * * Reads text from standard input using console I/O using the Scanner class. * This does not work in versions of Java previous to Java 5 (aka 1.5) * @author Dale Reed */ import java.util.Scanner; public class Midterm1Prep {
public static void main(String[] args) { Scanner keyboard = new Scanner( System.in);
System.out.print( "Enter some text: " ); String userInput = keyboard.nextLine();
// read a string
// go through all the characters and print out any upper case // characters for( int i=0; i<userInput.length(); i++) { // copy the ith character char c = userInput.charAt( i); // print it if it is upper case if( c >= 'A' && c <= 'Z') { System.out.print( c); }
} }//end main()
}//end class /* sample run: * Enter some text: DOWELL */
Dorks are Only Women when Entirely Late to Lunch
Questions?
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Questions?
Last Time: Scope Today: - Demo program to manipulate characters on an input line - Classes Example: Developing a Date class: What do we need to keep of? track How might this be used? See code developed in class. For each new idea we will have a demo program, and we will add the code to the class so that the demo program works. DateFirstTryDemo:
Ideas: Declare instances; Set instance variables (aka members, or class variables) using the "dot" notation. Think of making an instance like a "stamp", with values that can be filled in. Problem: Can set invalid values
DateSecondTryDemo:
Ideas: Making instance variables private; get (accessor) and set (mutator) methods; methods can change multiple values at once; method overloading Problem: Would like to create an instance and set its values in one step, rather than two. Can still enter invalid values, unless we add errorchecking code.
DateThirdTryDemo:
Ideas: Constructors are special code used to create and initialize instances. Constructors can also be chained to another constructor using this
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this Problems: Output of an instance is not consistent; Want to be able to compare instances based on their contents; Would like to be able to make a copy of an object.
DateFourthTryDemo:
Ideas: Handy utility methods: toString: gives nicely formatted output equals: allows comparing two instances copy constructor: allows making a copy based on an existing object
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