Populate java.awt.list from String Array

Question

I am trying to populate my java awt list from a string array. The string array gets the values from a .csv file. (Timezones) e.g Australia,Melbourne Australia,Sydney Europe,London

Note: There are two list boxes. First one for region and second one for City. The idea is to have the second one update after the user selects a region in the first one.

I can't seem to be able to populate the list from these values

Any help will be appreciated Thanks

String fileName = "C:\\Users\\Seb\\IdeaProjects\\TimeMachine\\src\\regions.csv";
    File file = new File(fileName);
    try {
        Scanner inputStream = new Scanner(file);
        inputStream.useDelimiter(System.getProperty("line.separator")); //Stops the white spaces creating a new entry in array
        while (inputStream.hasNext()) {
            String data = inputStream.next(); //gets the whole line
            String[] arrayLocations = data.split(",");
            System.out.println(arrayLocations[0]);
            System.out.println(arrayLocations[1]);

            listRegion = Arrays.asList(arrayLocations);
        }
        inputStream.close();

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

The error appears in listRegion = Arrays.asList(arrayLocations);

Entire code

import java.applet.Applet;
import java.awt.*;
import java.awt.List;
import java.io.*;
import java.util.Arrays;
import java.util.Scanner;

public class TimeMachine extends Applet
{
private List listRegion = new List();
private List listSubRegion = new List();

public void init ()
{
    setLayout(new BorderLayout());

    Panel buttons = new Panel(new BorderLayout());
    buttons.setBackground(Color.cyan);
    buttons.add(listRegion, BorderLayout.WEST);
    buttons.add(listSubRegion, BorderLayout.CENTER);
    add(buttons, BorderLayout.NORTH);
}

public void getLocationInfo()
{
    String fileName = "C:\\Users\\Seb\\IdeaProjects\\TimeMachine\\src\\regions.csv";
    File file = new File(fileName);
    try {
        Scanner inputStream = new Scanner(file);
        inputStream.useDelimiter(System.getProperty("line.separator")); //Stops the white spaces creating a new entry in array
        while (inputStream.hasNext()) {
            String data = inputStream.next(); //gets the whole line
            String[] arrayLocations = data.split(",");
            System.out.println(arrayLocations[0]);
            System.out.println(arrayLocations[1]);

            listRegion = Arrays.asList(arrayLocations);
        }
        inputStream.close();

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

}

Wouldn't it be easier to use a java.util.List?

Keppil
– Keppil

2013-05-20 13:15:33 +00:00
Commented May 20, 2013 at 13:15 — Keppil
– Keppil, Commented May 20, 2013 at 13:15
What is listRegion? What error do you get?

BobTheBuilder
– BobTheBuilder

2013-05-20 13:15:52 +00:00
Commented May 20, 2013 at 13:15 — BobTheBuilder
– BobTheBuilder, Commented May 20, 2013 at 13:15
Can you show java.util.List in a GUI window ?

Seb Welch
– Seb Welch

2013-05-20 13:16:21 +00:00
Commented May 20, 2013 at 13:16 — Seb Welch
– Seb Welch, Commented May 20, 2013 at 13:16

harsh · Accepted Answer · 2013-05-20 17:36:32Z

1

You are mixing both java.util.List and java.awt.List, use only java.awt.List:

listRegion = new List();
 while (inputStream.hasNext()) {
            String data = inputStream.next(); //gets the whole line
            String[] arrayLocations = data.split(",");
            System.out.println(arrayLocations[0]);
            System.out.println(arrayLocations[1]);
            for(String location : arrayLocations)
                 listRegion.add(location);
        }

More formally, below is a working code where region.csv must contain REGION,COUNTRY format where duplicates are handled:

import java.applet.Applet;
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.List;
import java.awt.Panel;
import java.awt.event.ItemEvent;
import java.awt.event.ItemListener;
import java.io.File;
import java.io.FileNotFoundException;
import java.util.Arrays;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Scanner;
import java.util.Set;

public class TimeMachine extends Applet implements ItemListener{
    private static final long serialVersionUID = 1L;

    private List listRegion = new List();
    private List listSubRegion = new List();
    private Map<String, Set<String>> regionCountryMap = new HashMap<String, Set<String>>();

    public void init()
    {
        setLayout(new BorderLayout());

        getLocationInfo();
        Panel buttons = new Panel(new BorderLayout());
        buttons.setBackground(Color.cyan);
        buttons.add(listRegion, BorderLayout.WEST);
        buttons.add(listSubRegion, BorderLayout.CENTER);
        add(buttons, BorderLayout.NORTH);
    }

    private void getLocationInfo() {
        String fileName = "e:\\regions.csv";
        File file = new File(fileName);
        try {
            Scanner inputStream = new Scanner(file);
            inputStream.useDelimiter(System.getProperty("line.separator"));
            listRegion = new List();
            while (inputStream.hasNext())
            {
                String data = inputStream.next(); // gets the whole line
                String[] arrayLocations = data.split(",");
                if(arrayLocations.length != 2){
                    System.out.println("Invalid entry in file : "+ Arrays.toString(arrayLocations));
                    continue;
                }
                String region = arrayLocations[0];
                if(!regionCountryMap.containsKey(region))
                {
                    listRegion.add(region);
                    regionCountryMap.put(region, new HashSet<String>());
                }
                regionCountryMap.get(region).add(arrayLocations[1]);//Set handles duplicates as well
            }
            inputStream.close();
            System.out.println("Region, Country list has been parsed successfully");
            listRegion.addItemListener(this);
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }
    }

    @Override
    public void itemStateChanged(ItemEvent e) {
        Set<String> countries = regionCountryMap.get(listRegion.getSelectedItem());
        listSubRegion.removeAll();
        for(String country : countries) {
            listSubRegion.add(country);
        }
        listSubRegion.validate();
        listSubRegion.repaint();
    }
}

edited May 20, 2013 at 17:36

answered May 20, 2013 at 13:28

harsh

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8 Comments

Seb Welch Over a year ago

Thanks so much. That worked perfectly. Is there anyway to only display [0] part of the array in the listRegion ?

harsh Over a year ago

Try using listRegion.select(index)

Seb Welch Over a year ago

Maybe I worded my question wrong but that didn't work. I tried 'list.region.add(location,1)' However that still displayed [1] parts of the array in the first list box. I only wants the regions to appear in their. Thanks for your help though but any other ideas

harsh Over a year ago

two things, you are not filling listSubRegion anywhere in the code and there is no logic implemented for maintaining region and country (subregions) association.

Seb Welch Over a year ago

Can I contact you outside this website to talk further about this. I would really appreciate your assistance with this project. Thanks

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