How can i find APIs for a weather forcast websites?

Question

I making a java application that give the user notification with the weather conditions. i used the yahoo weather API provided by yahoo like that link :

http://weather.yahooapis.com/forecastrss?w=2502265

and all i have to do is to change the eight numbered code that is in the URL in order to change the city.

that's working perfect, but there are two problems facing me now:

the first one, i want to implement a lot of weather forecast sources in my application not just the yahoo weather and i can't find a similar service in any other weather forecast websites.

the second one, i want to obtain the codes of all the cities in yahoo weather as for sure i won't ask the user to enter his city code, but to enter his city name and i'll match it with the code.

and here is the code that works with me in java:

the code to return the XML file:

package search;

import java.io.IOException;
import java.io.InputStream;
import java.io.StringWriter;
import java.net.URL;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.transform.OutputKeys;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;
import org.w3c.dom.Document;

    public class Process {

        public static void main(String[] args) throws IOException {

            Display disp = new Display();

            Document doc = generateXML("1940345");
            disp.getConditions(doc);

        }

        public static Document generateXML(String code) throws IOException {

            String url = null;
            String XmlData = null;

            // creating the URL
            url = "http://weather.yahooapis.com/forecastrss?w=" + code;
            URL xmlUrl = new URL(url);
            InputStream in = xmlUrl.openStream();

            // parsing the XmlUrl
            Document doc = parse(in);

            return doc;

        }

        public static Document parse(InputStream is) {
            Document doc = null;
            DocumentBuilderFactory domFactory;
            DocumentBuilder builder;

            try {
                domFactory = DocumentBuilderFactory.newInstance();
                domFactory.setValidating(false);
                domFactory.setNamespaceAware(false);
                builder = domFactory.newDocumentBuilder();

                doc = builder.parse(is);
            } catch (Exception ex) {
                System.err.println("unable to load XML: " + ex);
            }
            return doc;
        }
    }

the code to display the temperature and humidity in that city :

package search;

import java.io.File;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;

public class Display {

    static void getConditions(Document doc) {

        String city = null;
        String unit = null;

        try {

            doc.getDocumentElement().normalize();

            NodeList nList = doc.getElementsByTagName("rss");

            for (int temp = 0; temp < nList.getLength(); temp++) {

                Node nNode = nList.item(temp);

                if (nNode.getNodeType() == Node.ELEMENT_NODE) {

                    Element eElement = (Element) nNode;

                    NodeList nl = eElement
                            .getElementsByTagName("yweather:location");

                    for (int tempr = 0; tempr < nl.getLength(); tempr++) {

                        Node n = nl.item(tempr);

                        if (nNode.getNodeType() == Node.ELEMENT_NODE) {

                            Element e = (Element) n;
                            city = e.getAttribute("city");
                            System.out.println("The City Is : " + city);

                        }
                    }

                    NodeList nl2 = eElement
                            .getElementsByTagName("yweather:units");

                    for (int tempr = 0; tempr < nl2.getLength(); tempr++) {

                        Node n2 = nl2.item(tempr);

                        if (nNode.getNodeType() == Node.ELEMENT_NODE) {

                            Element e2 = (Element) n2;
                            unit = e2.getAttribute("temperature");

                        }
                    }

                    NodeList nl3 = eElement
                            .getElementsByTagName("yweather:condition");

                    for (int tempr = 0; tempr < nl3.getLength(); tempr++) {

                        Node n3 = nl3.item(tempr);

                        if (nNode.getNodeType() == Node.ELEMENT_NODE) {

                            Element e3 = (Element) n3;
                            System.out.println("The Temperature In " + city
                                    + " Is : " + e3.getAttribute("temp") + " "
                                    + unit);
                        }
                    }

                    NodeList nl4 = eElement
                            .getElementsByTagName("yweather:atmosphere");

                    for (int tempr = 0; tempr < nl4.getLength(); tempr++) {

                        Node n4 = nl4.item(tempr);

                        if (nNode.getNodeType() == Node.ELEMENT_NODE) {

                            Element e4 = (Element) n4;
                            System.out.println("The Humidity In " + city
                                    + " Is : " + e4.getAttribute("humidity"));
                        }
                    }

                }
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

}

Answer 1

You can use Metwit weather api simply passing latitude and longitude.
If you can implement them client-side: 200 request/day (ip based throttling) no authentication required. Worldwide coverage, JSON and REST compliant. You can register for extra API calls for free and if you still need it to call them server side the basic plan is pretty cheap.

Full disclosure: I own this API.