User Interface

In this homework, you need to use the user interface client code for working with your supplier classes. See the reference on the page.

Client class code

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GeoApp.java

import java.awt.*;

import javax.swing.*;

import java.awt.event.*;

import java.io.*;

/**

* Client App

*

*/

public class GeoApp

{

private JTextArea text;

/**

* Constructor for objects of class GPSApp

*/

public GeoApp()

{

JFrame win = new JFrame("142 GEO App");

win.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

win.setSize(500, 400);

// Create the button

JButton button = new JButton("Load Data");

// put button in a panel and then into the frame

JPanel back = new JPanel();

back.setBackground(Color.blue);

back.add(button);

win.add(back,BorderLayout.SOUTH );

// now set up the event handler

button.addActionListener(new ActionListener(){

public void actionPerformed(ActionEvent e){

process();

}

});

// create the display area and place it

text = new JTextArea();

JScrollPane scrolltxt = new JScrollPane(text);

win.add(scrolltxt, BorderLayout.CENTER);

// get the frame ready to show

win.validate();

win.setVisible(true);

win.toFront();

}

// processing the button click

private void process(){

// get filename from user

JFileChooser fc = new JFileChooser();

int returnVal = fc.showOpenDialog(null);

if (returnVal == JFileChooser.APPROVE_OPTION){

String filename = fc.getSelectedFile().getPath();

// create a LocationSet and display results

try {

GeoSet gs = new GeoSet(filename);

String results = buildDisplay(gs);

text.setText("File:\t" + filename + " ");

text.append(results);

} catch (FileNotFoundException e){

text.setText("Sorry, file not found Please try again");

}catch (IllegalArgumentException e) {

text.setText("Sorry, file must have at least 2

locations Please try again");

}

}

}

// build & return String for display using information from ls

private String buildDisplay(GeoSet gs)throws FileNotFoundException {

StringBuilder output = new StringBuilder();

Location lookUp = gs.find("Seattle");

Location[] furthest = gs.farthest();

double minD = gs.findMinDist();

output.append("Number of locations = " + gs.getCount() + ' ');

output.append("Min distance (mi) = " + minD + " ");

output.append("Farthest Locations \t" + furthest[0] + " \t" +

furthest[1] +" ");

output.append("\tdistance (mi) \t= " +

furthest[0].distance(furthest[1]) + " ");

if (lookUp !=null){

output.append("Seattle found: \t" + lookUp);

}

else {

output.append("Seattle not found");

}

output.append(" ========================== "+ gs);

return output.toString();

}

public static void main(String [] args) {

//Schedule a job for the event-dispatching thread:

//creating and showing this application's GUI.

javax.swing.SwingUtilities.invokeLater(new Runnable() {

public void run() {

GeoApp b = new GeoApp();

}

});

}

}

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Input Data Files and storage

The text file your program will read from follows this format:

start with one integer on its own line (how many objects are in this file)

followed by a series of lines. Each line contains 3 pieces of information: a location name (a single word) then latitude (lat) and longitude (long) pairs of doubles.

Latitude measures the number of degrees north or south of the equator (0 degrees). We will use signs to identify north (positive) or south (negative). The maximum value is 90 degrees, the minimum value is -90 degrees. For example, Seattle's latitude is 47.60835430674681 the latitude of McMurdo Station (Antarctica) is -77.85

Longitude measures the number of degrees east or west of the Greenwich Meridian (a line that goes from pole to pole around the earth through Greenwich, England). Positive longitudes are east of this meridian; negative longitudes are west of this meridian. The max is 180, the min is -180. Here are the lat/long for Seattle and McMurdo Station:

Seattle Latitude: 47.67340087890625 Longitude: -122.34259796142578

McMurdo Station Latitude: -77.85 Longitude: 166.6666667

Your program does not have to be responsible for files that do not match this format (in other words, if the end user gives you a filename with bad data and the program crashes, that's ok). You can create any text file you want for testing (use a program like Notepad or any other basic text editor). Here are some files I've created for you to use: locations1.txt or locations2.txt location1.txt

4

NSCC

47.699480

- 122.333536

Paris

48.860861

2.336419

NYC

40.747923

- 73.985217

DisneyLand

28.381646

- 81.563761

location2.txt

10

Cairo

30.044420

31.235712

London

51.508129

- 0.128005

Boston

42.358431

- 71.059773

GoldenGateBridge

37.818549

- 122.478676

GrandCanyon

36.055761

- 112.137451

Seattle

47.67340087890625

- 122.34259796142578

Antarctica

- 77.85

166.7

PanamaCanal

9.250548

- 79.876099

CapeTown

- 33.934245

18.369141

Seville

37.3898

- 5.976563

Make sure to look at and run the example programs that illustrate reading data from a file.

Code Specification

Implement the class specifications below. To get full credit, your program's public interface must match these descriptions exactly.

class Location

You decide your instance variables

+ Location(String name, double lat, double lon) -- initializes this Location object with the given name, and lat/long in degrees. Throws an IllegalArgumentException for invalid values.

< methods>

+ double getLatitude() -- returns the latitude of this location + double getLongitude() -- returns the longitude of this location + String getName() -- returns the name of this location + String toString() -- returns a String representation of this Location + double distance(Location l) -- returns the distance between this Location and the parameter. The algorithm is discussed below.

Distance Calcuation

To find the distance between two locations on the planet, we'll be using the Haversine Formula. This is a pretty complex calculation, so I'm giving you code to start with. Assume we have the lat/long of 2 locations, in degrees:

// earth's radius, in miles

double earthRadius = 3963.1;

// convert all angles to radians. Radians is another unit for measuring angles. Needed for trig methods

lat1 = Math.toRadians(lat1); // notice I'm reusing variables here. You probably won't want to do this in your solution.

lat2 = Math.toRadians(lat2);

lng1 = Math.toRadians(lng1);

lng2 = Math.toRadians(lng2);

// calculate the Haversine formula in pieces

double dLat = lat2-lat1;

double dLng = lng2-lng1;

double sindLat = Math.sin(dLat / 2);

double sindLon = Math.sin(dLng / 2);

double a = Math.pow(sindLat, 2) + Math.pow(sindLon, 2) * Math.cos(lat1) * Math.cos(lat2);

double c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1-a));

double dist = earthRadius * c;

The final answer is in the variable dist. Use this algorithm in your distance() method. When I was testing this code, I used this site to confirm my solutions

The other file to implement is this:

class GeoSet

You decide your instance variables. The one requirement is to use an array to hold all the Location objects.

+ GeoSet(String filename) throws FileNotFoundException-- initializes a GeoSet object using the data from the specified file name, where the file follows the format described above. The precondition is that the file must contain at least 2 lat/long pairs. Throw an IllegalArgumentException otherwise.

+ int getCount() -- returns the number of Locations in this set + double findMinDist() -- Based on the order that the Locations were loaded into this GeoSet, this method returns the smallest distance between 2 consecutive Locations in this set. + Location find(String name) -- returns the Location whose name matches the parameter. Return null if no match found.

+ Location[ ] farthest() -- returns an array with the 2 Locations from this GeoSet that are the farthest from each other. These 2 Locations are not necessarily consecutive in the set.

+ String toString() -- returns a String that contains the String representation for each Location object in this GeoSet, separate by ' '.

Suggestions

I hope by this point in the quarter you appreciate the benefit of working pieces of your solution one at a time. I recommend building and testing your Location class first. Next work on reading in the data (the GeoSet constructor method). Then tackle one or two methods at a time.

If it makes sense to decompose any of these methods, do so. However, the helper methods should all be private. Only these methods listed here should be part of the public interface.

Also, when dealing with the FileNotFoundException, every method that calls the GeoSet constructor needs the throws clause in its method signature (unless you want to use try/catch blocks in any client code, but that is not a requirement for this assignment).