Learning Processing: A Beginner's Guide to Programming Images ...

338 Learning Processing
String url = " http://xml.weather.yahoo.com/forecastrss?p = 10003 " ;
String[] lines = loadStrings(url);
// Get rid of the array in order to search
// the whole page
String xml = join(lines, " " );
// Searching for temperature
String tag1 = " temp = \ " " ;
String tag2 = " \ " " ;
temp = int(giveMeTextBetween
(xml,tag1,tag2));
println(temp);
Example 18-5 retrieves the temperature from Yahoo’s weather XML feed and displays it onscreen. Th e
example also uses object-oriented programming, putting all of the String parsing functionality into a
WeatherGrabber class.
Example 18-5: Parsing Yahoo’s XML weather feed manually
PFont f;
String[] zips = { " 10003 ", " 21209 ", " 90210 " } ;
int counter = 0;
// The WeatherGrabber object does the work for us!
WeatherGrabber wg;
void setup() {
size(200,200);
// Make a WeatherGrabber object
wg = new WeatherGrabber(zips[counter]);
// Tell it to request the weather
wg.requestWeather();
f = createFont( " Georgia " ,16,true);
}
void draw() {
background(255);
textFont(f);
fill(0);
// Get the values to display
String weather = wg.getWeather();
int temp = wg.getTemp();
// Display all the stuff we want to display
text(zips[counter],10,160);
text(weather,10,90);
text(temp,10,40);
text(" Click to change zip. " ,10,180);
// Draw a little thermometer based on the temperature
stroke(0);
fill(175);
rect(10,50,temp*2,20);
}
A quote in Java marks the beginning or end of a String. So how
do we include an actual quote in a String?
The answer is via an “escape” sequence. (We encountered this
in Exercise 17-8.) A quote can be included in a String using a
backward slash, followed by a quote. For example:
String q = "This String has a quote \"in it";
fi g. 18.9
The WeatherGrabber object is initialized with
a zip code. The XML data is loaded and parsed
upon calling the requestWeather() function.
The weather and temperature information is
pulled from the WeatherGrabber object.