hello/java/samples/properties/swing1/MainFrame.java

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package propertiesswing;

import java.awt.Container;
import java.awt.FlowLayout;
import java.awt.GridLayout;
import java.awt.Label;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.util.Properties;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.swing.JButton;
import javax.swing.JFileChooser;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;

/**
 *
 * @author denis
 */
public class MainFrame extends JFrame{
    
    private File file;
    private Properties properties;
    private JTextField currentField = new JTextField(50);
    private JTextField powerField = new JTextField(50);
    private JTextField frecField = new JTextField(50);
    
    public MainFrame(){
        setTitle("Propetries");
        setSize(600, 600);
        Container container = getContentPane();
        GridLayout layout = new GridLayout(0, 1);
        container.setLayout(layout);
        container.add(initManageButtons());
        container.add(initFields("Current: ", currentField));
        container.add(initFields("Power: ", powerField));
        container.add(initFields("Frec: ", frecField));
        
        setLocationRelativeTo(null);
        setDefaultCloseOperation(DISPOSE_ON_CLOSE);
        pack();
        setVisible(true);
    }
    
    private JPanel initFields(String textLabel, JTextField field){
        JPanel panel = new JPanel(new FlowLayout());
        JLabel label = new JLabel(textLabel);
        panel.add(label);
        panel.add(field);
        return panel;
    }
    
    private void initFileChooser(){
        JFileChooser chooser = new JFileChooser();
        chooser.setFileSelectionMode(JFileChooser.FILES_ONLY);
        int result = chooser.showOpenDialog(this);
        if(result == JFileChooser.APPROVE_OPTION){
            file = chooser.getSelectedFile();
        }
    }
    
    private JPanel initManageButtons(){
        JPanel panel = new JPanel(new FlowLayout(10, 20, 20));
        JButton openButton = new JButton("Open file");
        panel.add(openButton);
        openButton.addActionListener(e -> {
            initFileChooser();
            if(file!=null && file.exists() && file.canRead()){
                loadProperties();
                if(properties!=null) {
                    if(currentField!=null) currentField.setText(properties.getProperty("Current"));
                    if(powerField!=null) powerField.setText(properties.getProperty("Power"));
                    if(frecField!=null) frecField.setText(properties.getProperty("Frec"));
                }
            }
        });
        JButton saveButton = new JButton("Save file");
        panel.add(saveButton);
        saveButton.addActionListener(e -> {
            if(file!=null && properties!=null){
                properties.put("Current", currentField.getText());
                properties.put("Power", powerField.getText());
                properties.put("Frec", frecField.getText());
                saveProperties();
            }
        });
        return panel;
    }
    
    
    
    private void loadProperties(){
        properties = new Properties();
        try {
            properties.load(new FileReader(file));
        } catch (FileNotFoundException ex) {
            Logger.getLogger(MainFrame.class.getName()).log(Level.SEVERE, null, ex);
        } catch (IOException ex) {
            Logger.getLogger(MainFrame.class.getName()).log(Level.SEVERE, null, ex);
        }
    }
    
    private void saveProperties(){
        if(properties!=null){
            try {
                properties.store(new FileWriter(file), null);
            } catch (IOException ex) {
                Logger.getLogger(MainFrame.class.getName()).log(Level.SEVERE, null, ex);
            }
        }
    }
    
}