Java homework assignment - Struggling

**Ganon11** · Feb 8 '07, 10:58 PM

What have you accomplished on this problem alone? What code do you have? What ideas do you have?

**matchuglenn** · Feb 9 '07, 06:01 PM

I have nothing, kind of hoping some Really nice people on here could give me some ideas and help really.

**RedSon** · Feb 9 '07, 07:15 PM

Originally posted by matchuglenn

I have nothing, kind of hoping some Really nice people on here could give me some ideas and help really.

Well first you need to do a design. What kind of design would you need to accomplish your task? What does the flow of information look like. At a high level what do you have to do?

- Read a file
- Tokenize and parse the input
- Do some calculations on it
- Then what?

**abctech** · Feb 10 '07, 09:07 AM

Originally posted by matchuglenn

1: A Geographic Distance Calculator
Write an application to calculate a table of geographic distances. The input of your application is a file containing
the coordinates of cities in latitude / longitude pairs, where latitude and longitude are given in degrees and minutes,
as in:1

Edinburgh 55;57N 03;13W
London 51;30N 0;30W
NorthWalsham 52;50N 01;22E
Norwich 52;38N 01;18E
Notice that 1 degree = 60 minutes. The output should be a text fille containing a table of geographic distances in
kilometres:

Edinburgh 0.00 520.90 452.43 467.11
London 520.90 0.00 194.50 175.33
NorthWalsham 452.43 194.50 0.00 22.57
Norwich 467.11 175.33 22.57 0.00

The application should take the names of the input fille (giving the latitude / longitude coordinates) and the output
fille (into which the distance table is written) from the first and second command line parameter. For example, if
your project is called geodist and your input file is cities.txt, the command line

java -jar geodist.jar cities.txt distances.txt

should write the distance table into distances.txt.

The procedure for calculating distances in kilometres is: One degree of latitude corresponds to 111 kilometres. One
degree of longitude corresponds to 111 . cos(') kilometres, where ' is the latitude.2 For example, the coordinates
of Norwich in kilometres are (111 . 1:3 . cos(52:63 degrees) = 87:57 kilometres east of Greenwich's longitude, 111 .
52:63 = 5842:28 kilometres north of the equator), those of North Walsham are (91:64, 5864:48).
The Euclidean distance between these two is
Square.route(87 :57- 91:64)^2 + (5842:28- 5864:48)^2 = square.route(-4:07)^2 + (-22:2)^2 = 22:57

Your application should comprise a class that adequately represents the geographic location of a city
and provides good support for carrying out this calculation.

If you are clueless about a particular program try thinking if you were to do it manually instead of writing an application then how would you go about it.Jot those points down as an algorithm and then get started.Might help generate some ideas!

**r035198x** · Feb 12 '07, 05:47 AM

You better learn how to make jar files too.

**matchuglenn** · Feb 13 '07, 03:38 PM

I am using Netbeans 5.0 and my code so far is:
It should read in the file Geo do some stuff to see if the file exsists and then split the bits of the text file up into parts of an arraylist.
Is this the right sort of thing.
And for some reason Netbeans doesnt like some of my code, it says
"
Cannot find symbol
symbol: class Geo
location: class calculator.Main
"

Code:


package calculator;
import java.io.*;


/**
 *
 * @author Matthew
 */
public class Main {
    
    /** Creates a new instance of Main */
    public Main() {
    }
    
    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        BufferedReader in  = getReader("Geo.txt");
        
        Geo geo = readGeo(in);
        while (geo != null)
        {
            String msg = geo.location;
        }
    }
    


private static BufferedReader getReader(String name)
{
    BufferedReader in = null;
    try
    {
        File file = new file(name);
        in = new BufferedReader(
                new FileReader(file) );
    }
    catch (FileNotFoundException e)
    {
        System.out.println("The File does not exsist");
        System.exit(0);
    }
    catch (IOException e)
    {
        System.out.println("I/O Error");
        System.exit(0);
    }
    return in;
}

private static Geo readGeo(BufferedReader in)
{
    String location;
    String line = "";
    String[] data;
    String[] data2;
    
    try
    {
        line = in.readLine();
    }
    catch (IOException e)
    {
        System.out.println("I/O Error");
        System.exit(0);        
    }
    
    if (line == null)
        return null;
    else 
    {
        data = line.split ("\t");
        location = data[0];
        data2 = line.split (";");
        
        
        
    }
}

}

**r035198x** · Feb 13 '07, 03:43 PM

Originally posted by matchuglenn

I am using Netbeans 5.0 and my code so far is:
It should read in the file Geo do some stuff to see if the file exsists and then split the bits of the text file up into parts of an arraylist.
Is this the right sort of thing.
And for some reason Netbeans doesnt like some of my code, it says
"
Cannot find symbol
symbol: class Geo
location: class calculator.Main
"

Code:

 
 
package calculator;
import java.io.*;
 
 
/**
*
* @author Matthew
*/
public class Main {
 
/** Creates a new instance of Main */
public Main() {
}
 
/**
* @param args the command line arguments
*/
public static void main(String[] args) {
BufferedReader in = getReader("Geo.txt");
 
Geo geo = readGeo(in);
while (geo != null)
{
String msg = geo.location;
}
}
 
 
 
private static BufferedReader getReader(String name)
{
BufferedReader in = null;
try
{
File file = new file(name);
in = new BufferedReader(
new FileReader(file) );
}
catch (FileNotFoundException e)
{
System.out.println("The File does not exsist");
System.exit(0);
}
catch (IOException e)
{
System.out.println("I/O Error");
System.exit(0);
}
return in;
}
 
private static Geo readGeo(BufferedReader in)
{
String location;
String line = "";
String[] data;
String[] data2;
 
try
{
line = in.readLine();
}
catch (IOException e)
{
System.out.println("I/O Error");
System.exit(0); 
}
 
if (line == null)
return null;
else 
{
data = line.split ("\t");
location = data[0];
data2 = line.split (";");
 
 
 
}
}
 
}

Well you don't have a class called Geo (or have not compiled it yet) but you are trying to create an object of type Geo.

What do you want the readGeo method to do exactly.

**RedSon** · Feb 13 '07, 03:44 PM

Originally posted by matchuglenn

I am using Netbeans 5.0 and my code so far is:
It should read in the file Geo do some stuff to see if the file exsists and then split the bits of the text file up into parts of an arraylist.
Is this the right sort of thing.
And for some reason Netbeans doesnt like some of my code, it says
"
Cannot find symbol
symbol: class Geo
location: class calculator.Main
"

Code:


package calculator;
import java.io.*;


/**
 *
 * @author Matthew
 */
public class Main {
    
    /** Creates a new instance of Main */
    public Main() {
    }
    
    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        BufferedReader in  = getReader("Geo.txt");
        
        Geo geo = readGeo(in);
        while (geo != null)
        {
            String msg = geo.location;
        }
    }
    


private static BufferedReader getReader(String name)
{
    BufferedReader in = null;
    try
    {
        File file = new file(name);
        in = new BufferedReader(
                new FileReader(file) );
    }
    catch (FileNotFoundException e)
    {
        System.out.println("The File does not exsist");
        System.exit(0);
    }
    catch (IOException e)
    {
        System.out.println("I/O Error");
        System.exit(0);
    }
    return in;
}

private static Geo readGeo(BufferedReader in)
{
    String location;
    String line = "";
    String[] data;
    String[] data2;
    
    try
    {
        line = in.readLine();
    }
    catch (IOException e)
    {
        System.out.println("I/O Error");
        System.exit(0);        
    }
    
    if (line == null)
        return null;
    else 
    {
        data = line.split ("\t");
        location = data[0];
        data2 = line.split (";");
        
        
        
    }
}

}

You might want to search the APIs for a tokenize method or string tokenizer. The way that you are reading in your file is not very object oriented.

**matchuglenn** · Feb 13 '07, 04:24 PM

Originally posted by r035198x

Well you don't have a class called Geo (or have not compiled it yet) but you are trying to create an object of type Geo.

What do you want the readGeo method to do exactly.

The readGeo should read in the file that the buffered reader has, which should be geo.text and then split bits of the text file up into array parts so that i can then do some calculations on them.

If i create a new class, Geo, how do i get the main part of the code to refer to it. Netbeans is annoying!!!

**matchuglenn** · Feb 13 '07, 04:27 PM

Originally posted by RedSon

You might want to search the APIs for a tokenize method or string tokenizer. The way that you are reading in your file is not very object oriented.

I dont think a tokenizer will help me with this to be honest.

**RedSon** · Feb 13 '07, 04:31 PM

Originally posted by matchuglenn

The readGeo should read in the file that the buffered reader has, which should be geo.text and then split bits of the text file up into array parts so that i can then do some calculations on them.

If i create a new class, Geo, how do i get the main part of the code to refer to it. Netbeans is annoying!!!

If you create the class Geo, you need to make sure that it is on your CLASSPATH. I don't think you need to import it but you could do that also.

**r035198x** · Feb 13 '07, 04:37 PM

Originally posted by matchuglenn

The readGeo should read in the file that the buffered reader has, which should be geo.text and then split bits of the text file up into array parts so that i can then do some calculations on them.

If i create a new class, Geo, how do i get the main part of the code to refer to it. Netbeans is annoying!!!

Netbeans is quite alright. I wouldn't advice beginners to use IDEs however ...

Now you don't need another class. Just a method readGeo is fine.
You want to create arrays using data that is in a file. How is the data arranged in the file and how do you want it to be stored in the arrays.

**matchuglenn** · Feb 13 '07, 06:11 PM

Originally posted by r035198x

Netbeans is quite alright. I wouldn't advice beginners to use IDEs however ...

Now you don't need another class. Just a method readGeo is fine.
You want to create arrays using data that is in a file. How is the data arranged in the file and how do you want it to be stored in the arrays.

In the text file, Geo.text, the data is arranged as follows:

Edinburgh 55;57N 03;13W
London 51;30N 0;30W
NorthWalsham 52;50N 01;22E
Norwich 52;38N 01;18E

In the code before i am attempting to split each line up, like:
Edingburgh in data[0] and 55 in data[1] and so on. then i can use these to carry out some calculations for the answer.

**r035198x** · Feb 13 '07, 07:26 PM

Originally posted by matchuglenn

In the text file, Geo.text, the data is arranged as follows:

Edinburgh 55;57N 03;13W
London 51;30N 0;30W
NorthWalsham 52;50N 01;22E
Norwich 52;38N 01;18E

In the code before i am attempting to split each line up, like:
Edingburgh in data[0] and 55 in data[1] and so on. then i can use these to carry out some calculations for the answer.

in the readGeo
do

Code:

 FileReader file = new FileReader("fileName.txt"); 
BufferedReader input = new BufferedReader(file);
String line  = input.readLine();

and now you have the first line in the string line

Java homework assignment - Struggling

Java homework assignment - Struggling

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