java - assign HashMap values to dynamic jComboBoxes

Question

I am loading text file contents to GUI and counting HashMap values using this code:

Map<String, ArrayList<String>> sections = new HashMap<>();
Map<String, String> sections2 = new HashMap<>();
String s = "", lastKey="";
try (BufferedReader br = new BufferedReader(new FileReader("input.txt"))) {
    while ((s = br.readLine()) != null) {
        String k = s.substring(0, 10).trim();
        String v = s.substring(10, s.length() - 50).trim();
        if (k.equals(""))
            k = lastKey;

            ArrayList<String> authors = null;
        if(sections.containsKey(k))
        {
            authors = sections.get(k);
        }
        else
        {
            authors = new ArrayList<String>();
            sections.put(k, authors);
        }
        authors.add(v);
        lastKey = k;
    }
} catch (IOException e) {
}

// to get the number of authors
int numOfAuthors = sections.get("AUTHOR").size();
// to count HashMap value
jButton1.addActionListener(new Clicker(numOfAuthors));
jButton1.doClick();

// convert the list to a string to load it in a GUI
String authors = "";
for (String a : sections.get("AUTHOR"))
{
    authors += a;
}
   jcb1.setSelectedItem(authors);

The ActionListener of jButton1 was borrowed from here.

Now I want to assign AUTHOR (the number of items in HashMap is 12, so jButton1 will add dynamic 12 jComboBoxes) values to dynamically created jComboBoxes.

I have tried this code:

BufferedReader br = new BufferedReader(new FileReader ("input.txt"));
String str=null;
int i = 0;
while( (str = br.readLine()) !=null ) {
    String v = str.substring(12, str.length() - 61).trim();

    if(i == 0) {              
        jcb1.setSelectedItem(v);

    } else {
        SubPanel panel = (SubPanel) jPanel2.getComponent(i - 1);
        JComboBox jcb = panel.getJcb();
        jcb.setSelectedItem(v);
    }

    i++;
}

But this code read from input.txt all lines (70 lines), but I want to assign just that 12 values from AUTHOR field and show them on jcb.

How can I solve it?

Answer 1

You shouldn't have to re-read the entire text file again in order to complete the setup of the GUI. I would just read the text file once, then use the Map<String, ArrayList<String>> sections = new HashMap<>(); object to complete the setup of the GUI.

This could be the process for you:

1) Read the entire file and return the sections HashMap.

2) Setup the jPanel2 by adding the SubPanels to it (e.g. based on the number of Authors).

3) Setup the JComboBox's by adding the data stored in the HashMap (e.g. the mapped ArrayList's).

For number 1), I would just create a method that reads the file and returns the HashMap.

Read The File

Example (Adapted from your other question here):

public Map<String, ArrayList<String>> getSections ()
{
    Map<String, ArrayList<String>> sections = new HashMap<>();
    String s = "", lastKey = "";
    try (BufferedReader br = new BufferedReader(new FileReader("input.txt")))
    {
        while ((s = br.readLine()) != null)
        {
            String k = s.substring(0, 10).trim();
            String v = s.substring(10, s.length() - 50).trim();
            if (k.equals(""))
                k = lastKey;

            ArrayList<String> authors = null;
            if (sections.containsKey(k))
            {
                authors = sections.get(k);
            }
            else
            {
                authors = new ArrayList<String>();
                sections.put(k, authors);
            }

            // don't add empty strings
            if (v.length() > 0)
            {
                authors.add(v);
            }
            lastKey = k;
        }
    }
    catch (IOException e)
    {
        e.printStackTrace();
    }
    return sections;
}

GUI Setup

Note: This code can be put wherever you are setting up the GUI now, I'm just placing all in the method below for an example.

public void setupGUI ()
{
    // read the file and get the map
    Map<String, ArrayList<String>> sections = getSections();

    // get the authors
    ArrayList<String> authors = sections.get("AUTHOR");

    // Setup the jPanel2 by adding the SubPanels
    int num = authors.size();
    jButton1.addActionListener(new Clicker(num));
    jButton1.doClick();

    // Setup the JComboBox's by adding the data stored in the map
    for (int i = 0; i < authors.size(); i++)
    {
        int index = i;
        // not sure if getComponent() is zero or 1-baed so adjust the index accordingly.
        SubPanel panel = (SubPanel) jPanel2.getComponent(index);

        // Not sure if you already have the JComboBox in the SubPanel
        // If not, you can add them here.

        JComboBox jcb = panel.getJcb();
        jcb.setSelectedItem(authors.get(i));
    }
}

Side Note: I'm not sure why you are creating 12 separate SubPanel's, each with its own JComboBox? Maybe you want to consider how you can better layout the GUI. Just a consideration. In either case, you can use the above examples are a starting point.