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• A brief description of the this program:

  • Write a program to prompt the user name of a city and output some information about it's weather.

• Objectives:

  1. Getting familiar with JSON.
  2. Learn how to establish a HTTP Connection to a API.
  3. Parsing desired data from JSON.

• An overview of the approach has taken to complete assignment:

  1. Establish a HTTP Connection to API.
  2. drop the data retrieved from API to a Buffered Reader and then append it line by line to a StringBuilder. After that we return it as a String.
  3. Call a function to split desired data into parts by JSON and output that.

• Describing code line by line:

  1. Set up API KEY.

     public class BonusTasks
     {
         public final static String apiKey = "4559ae7bd83f44d5ba911803232502";
         ......
     }

  2. Input city name from user.

     public static void main(String[] args)
         {
             Scanner input = new Scanner(System.in);
             System.out.println("Enter the city: ");
             String city = input.nextLine();
             .......
         }
        

  3. Call getWeatherData() to establish a connection to API and return the String containing all data.

  public static void main(String[] args)
  {
  	......
  	......
  	if (getWeatherData(city) != null)
          {
              String weatherJson = getWeatherData(city);
              showWeatherInfo(weatherJson);
          }
          else
          {
              System.out.print("No information found!");
          }
  }
  
  public static String getWeatherData(String city)
      {
          try
          {
              URL url = new URL("http://api.weatherapi.com/v1/current.json?key=" + apiKey + "&q=" + city);
              HttpURLConnection connection = (HttpURLConnection) url.openConnection();
              connection.setRequestMethod("GET");
              BufferedReader reader = new BufferedReader(new 					InputStreamReader(connection.getInputStream()));
              StringBuilder stringBuilder = new StringBuilder();
              String line;
              while ((line = reader.readLine()) != null)
              {
                  stringBuilder.append(line);
              }
              reader.close();
              return stringBuilder.toString();
          }
          catch (Exception e)
          {
              return null;
          }
      }

  • For that we first set our URL to a specified format like the picture above and establish a connection to that.

  • Then we have set the requestMethod to "GET".

  • Insert data that we read from connection stream in a Buffered reader and append it line by line to StringBuilder.

  • Close the connection and our buffer, Then return the String builder as a String.

4. Call the showWeatherInfo() and pass the String to it:

   public static double getTemperature(String weatherJson)
   {
       JSONObject jsonObject = new JSONObject(weatherJson);
       double answer = jsonObject.getJSONObject("current").getDouble("temp_c");
       return answer;
   }
   public static int getHumidity(String weatherJson)
   {
       JSONObject jsonObject = new JSONObject(weatherJson);
       int answer = jsonObject.getJSONObject("current").getInt("humidity");
       return answer;
   }
   public static double getWindSpeed (String weatherJson)
   {
       JSONObject jsonObject = new JSONObject(weatherJson);
       double answer = jsonObject.getJSONObject("current").getDouble("wind_kph");
       return answer;
   }
   public static String getDirection (String weatherJson)
   {
       JSONObject jsonObject = new JSONObject(weatherJson);
       String answer = jsonObject.getJSONObject("current").getString("wind_dir");
       return answer;
   }

5. After that we call the methods getTemperature(), getHumidity(), getWindSpeed(), getDirection(), one after the other to parse trough String by JSON Methods and return asked information.

public static void showWeatherInfo (String weatherJson)
    {
        double temperature = getTemperature(weatherJson);

        int humidity = getHumidity(weatherJson);

        double wind_speed = getWindSpeed(weatherJson);

        String wind_direction = getDirection(weatherJson);
        .....
    }

6. Pass the information to be arranged in a GUI frame:

public static void showWeatherInfo (String weatherJson)
    {
        ....
        ....
        ...
                GUI gui = new GUI(String.valueOf(temperature), String.valueOf(humidity), String.valueOf(wind_speed), wind_direction);

    }
.....
.....
//in the GUI.java file we implented Graphic User Interface of the application
public class GUI
{
    JFrame frame;
    JPanel panel;
    JLabel label_1;
    JLabel label_2;
    JLabel label_3;
    JLabel label_4;
    public GUI(String temperature, String humidity, String wind_speed, String wind_direction)
    {
        label_1 = new JLabel("Temperature: " + temperature); //setting text of the label
        label_1.setLayout(null); //setting layout manager to null because we want to set positions manually
        label_1.setBounds(0, 0, 100, 100); //setting bounds of the label
        label_1.setFont(new Font("Segoe UI Black", Font.PLAIN, 20)); //setting style of the text
        label_1.setForeground(new Color(200, 200, 0)); //setting color of the text

        label_2 = new JLabel("Humidity Percentage: " + humidity); //same as above
        label_2.setLayout(null);                                                
        label_2.setBounds(0, 100, 100, 100);                  
        label_2.setFont(new Font("Segoe UI Black", Font.PLAIN, 20)); 
        label_2.setForeground(new Color(200, 200, 0));                 

        label_3 = new JLabel("Winds Speed: " + wind_speed);
        label_3.setLayout(null);
        label_3.setBounds(0, 200, 100, 100);
        label_3.setFont(new Font("Segoe UI Black", Font.PLAIN, 20));
        label_3.setForeground(new Color(200, 200, 0));

        label_4 = new JLabel("Winds Direction: " + wind_direction);
        label_4.setLayout(null);
        label_4.setBounds(0,300, 100, 100);
        label_4.setFont(new Font("Segoe UI Black", Font.PLAIN, 20));
        label_4.setForeground(new Color(200, 200, 0));

        panel = new JPanel();  //creating a panel
        panel.add(label_1);    //adding labels to the panel one by one
        panel.add(label_2);
        panel.add(label_3);
        panel.add(label_4);
        panel.setBackground(Color.BLUE);  //setting background color
        panel.setOpaque(true);    //set this true to display background color

        ImageIcon imageIcon = new ImageIcon("WeatherForecaster.png");   //creating frame icon
        frame = new JFrame();  //creating a frame
        frame.add(panel); //adding panel and all components to the frame
        frame.setVisible(true);  //set this to true to display the frame
        frame.setIconImage(imageIcon.getImage()); //setting image icon
        frame.setTitle("Weather Forecast Program");  //setting the title text
        frame.setSize(400, 200);  //setting size of frame
        frame.setResizable(false);  //prevent the frame to be resized
    }

1. Input the city name:

   

2. Wait a few seconds and as you can see that a window comes up and information showed in:

   

3. Now let's test a special case that our city doesn't exist and see what happens:

   

4. As you can see in the picture above nothing has been shown because "sare ghabram" does not exist in API cities.