Question

How to put a dropdown list that has the list of every string, and when I select a item on that list then push the load button it will only show up what’s on that String. Here’s my code, I actually put the number of the string and and show the String’s data using while statements.

How can I actually put a Dropdown list and it’s content will be a number registered on every string. Just like this

1 231231

2 123124

3 123124

4 232312

If I select 4 and press “Load” it will show “232312”
and everytime I save a data a unique number will be registered in every line, just like
“4” is the unique no. and 232312 is it’s data

package datasaving;
import java.awt.HeadlessException;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.*;
import javax.swing.*;

public class Datasaving {

    /**
     * @param args the command line arguments
     * @throws FileNotFoundException
     * @throws IOException  
     */
    public static void main(String[] args) throws FileNotFoundException, IOException {
        JPanel panel = new JPanel();
        JFrame frame = new JFrame();
        final JTextField input0 = new javax.swing.JTextField(20);
        final JTextField input1 = new javax.swing.JTextField(20);
        final JTextField out = new javax.swing.JTextField(20);
        final JTextField line = new javax.swing.JTextField(20);

        JButton save = new javax.swing.JButton("Save");
        JButton load = new javax.swing.JButton("Load");
        frame.add(panel);
        frame.setSize(240,200);
        panel.add(input0);
        panel.add(input1);
        panel.add(save);
        panel.add(line);
        panel.add(out);
        panel.add(load);

        frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
        frame.setVisible(true);





        save.addActionListener(new ActionListener() {
                            @Override
                            public void actionPerformed(ActionEvent e) {
                                 File file = new File("data.dat");

                            try {
                                 try (FileWriter writer = new FileWriter(file, true)) {
                                 String data0 = input0.getText();
                                 String data1 = input1.getText();
                                 writer.write(data0+":"+data1+"\n");
                                }

                                System.out.println("Data Saved");
                                } catch (IOException | HeadlessException z) {
                                JOptionPane.showMessageDialog(null, e);
                                }
                                } 
                                });
        load.addActionListener(new ActionListener() {
                            @Override
                            public void actionPerformed(ActionEvent e) {

                                 int lines = Integer.parseInt(line.getText());


                                     try {
                                 FileInputStream fs= new FileInputStream("data.dat");
                                 BufferedReader br = new BufferedReader(new InputStreamReader(fs));
                                 for(int i = 0; i < lines; ++i) {
                                 br.readLine();
                                 }
                                 out.setText(br.readLine());



                                JOptionPane.showMessageDialog(null, "Loaded");
                                } catch (   IOException | HeadlessException es) {
                                JOptionPane.showMessageDialog(null, e);
                                }
                                 }


                                });



    }
}

for example:
John blahblahblahblah
Keith blahblahblahblah
Joe blahblahblahblah
Kenneth blahblahblahblah
Christian blahblahblahblah
The first word “Names” will be added to JList or JComboBox
how to make the names a Array. I know how to use .split(); but I don’t know how to make that happen in every lines in the file

Answer 1

1) JTextField doesn’t support multi-line. Try JTextArea instead. With text areas, you can use myTextArea.append() to add lines as you read them.

2) But actually, it sounds like a JComboBox or a JList might be what you’re really looking for:

• http://docs.oracle.com/javase/tutorial/uiswing/components/combobox.html

3) Your basic program looks OK

‘Hope that helps!