Tags: How to , Swing

This article stands in front of my all other articles. I got so many request to update its content for better user experience so here I am.

Swing
Swing is built on base of Abstract Window Toolkit (AWT). In other words swing is extended version of AWT for better and richer user interface. Its used to create desktop applications like chat, accounting and so on.

Read more How to get list of opened JFrame in Java Swing?
Read more Sample Client - Server Chat Application in Java

Creating ParentJFrame with following components.

• Text Field to type message
• Button to send message

/* This example is coded in NetBeans so you'll find some IDE generated code unexplained. */
package com.javaquery.swing;

import java.awt.Frame;
import java.util.Date;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.swing.JOptionPane;
import javax.swing.LookAndFeel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

public class ParentJFrame extends javax.swing.JFrame {

    public ParentJFrame() {
        initComponents();
    }

    @SuppressWarnings("unchecked")                      
    private void initComponents() {
        lblInfo = new javax.swing.JLabel();
        textField = new javax.swing.JTextField();
        btnSend = new javax.swing.JButton();

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
        setTitle("Parent JFrame");

        lblInfo.setText("Message");

        btnSend.setText("Send Message");
        btnSend.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                btnSendActionPerformed(evt);
            }
        });

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addContainerGap()
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
                    .addComponent(btnSend)
                    .addGroup(layout.createSequentialGroup()
                        .addComponent(lblInfo)
                        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                        .addComponent(textField, javax.swing.GroupLayout.PREFERRED_SIZE, 212, javax.swing.GroupLayout.PREFERRED_SIZE)))
                .addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addContainerGap()
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(lblInfo)
                    .addComponent(textField, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
                .addGap(18, 18, 18)
                .addComponent(btnSend)
                .addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
        );

        pack();
    }                        

    private void btnSendActionPerformed(java.awt.event.ActionEvent evt) {                                        
        /* Get text from TextField */
        String message = textField.getText();
        String setNewMessage = "";
        boolean isFrameOpen = false;

        if (message != null && message.length() > 0) {
            /**
             * Get list of opened JFrames 
             * Read more about "How to get list of opened JFrame in Java Swing?"
             * http://www.javaquery.com/2014/06/how-to-get-list-of-opened-jframe-in.html
             */
            for (Frame frame : Frame.getFrames()) {
                /* Match title of JFrame */
                if (frame.getTitle().equals("Child JFrame")) {
                    /* Cast to ChildJFrame */
                    ChildJFrame childJFrame = (ChildJFrame) frame;
                    /**
                     * Access TextArea of ChildJFrame using getter method. 
                     * You can so same for other component like JLabel, Buttons,
                     * Combobox, List by creating getter and setter method.
                     */
                    String getPreviousMessages = childJFrame.getTextArea().getText();
                    if (getPreviousMessages.length() > 0) {
                        /* Append new message to String */
                        setNewMessage = getPreviousMessages + "\n[" + new Date().toString() + "]: " + message;
                    } else {
                        /* Create new message String */
                        setNewMessage = "[" + new Date().toString() + "]: " + message;
                    }

                    /* Set value of TextArea */
                    childJFrame.getTextArea().setText(setNewMessage);
                    isFrameOpen = true;
                }
            }

            /* If ChildJFrame is not opened yet */
            if (!isFrameOpen) {
                /* Create new message String */
                setNewMessage = "[" + new Date().toString() + "]: " + message;
                /* Create an object of ChildJFrame */
                ChildJFrame childJFrame = new ChildJFrame();
                /* Set message in TextArea */
                childJFrame.getTextArea().setText(setNewMessage);
                /* Make ChildJFrame visible */
                childJFrame.setVisible(true);
            }
        } else {
            /* Alert box when user try to send blank message */
            JOptionPane.showMessageDialog(null, "Type something to send");
        }
    }                                       

    public static void main(String args[]) {
        /* Create and display the form */
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {

                /**
                 * Read more about "How to apply/set up swing look and feel?"
                 * http://www.javaquery.com/2013/06/how-to-applyset-up-swing-look-and-feel.html
                 */
                try {
                   UIManager.setLookAndFeel("com.sun.java.swing.plaf.nimbus.NimbusLookAndFeel");
                } catch (ClassNotFoundException ex) {
                    Logger.getLogger(LookAndFeel.class.getName()).log(Level.SEVERE, null, ex);
                } catch (InstantiationException ex) {
                    Logger.getLogger(LookAndFeel.class.getName()).log(Level.SEVERE, null, ex);
                } catch (IllegalAccessException ex) {
                    Logger.getLogger(LookAndFeel.class.getName()).log(Level.SEVERE, null, ex);
                } catch (UnsupportedLookAndFeelException ex) {
                    Logger.getLogger(LookAndFeel.class.getName()).log(Level.SEVERE, null, ex);
                }
                new ParentJFrame().setVisible(true);
            }
        });
    }
    // Variables declaration - do not modify                     
    private javax.swing.JButton btnSend;
    private javax.swing.JLabel lblInfo;
    private javax.swing.JTextField textField;
    // End of variables declaration                   
}

Creating ChildJFrame with following components.

• Text Area (Create Getter and Setter method)

ChildJFrame is aimed to receive messages so there ain't much coding.

/* This example is coded in NetBeans so you'll find some IDE generated code unexplained. */
package com.javaquery.swing;

public class ChildJFrame extends javax.swing.JFrame {
    public ChildJFrame() {
        initComponents();
    }

    @SuppressWarnings("unchecked")
    private void initComponents() {
        scrollPane = new javax.swing.JScrollPane();
        textArea = new javax.swing.JTextArea();
        lblInfo = new javax.swing.JLabel();

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
        setTitle("Child JFrame");

        textArea.setColumns(20);
        textArea.setRows(5);
        scrollPane.setViewportView(textArea);

        lblInfo.setText("Message Received");

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addContainerGap()
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addComponent(scrollPane, javax.swing.GroupLayout.DEFAULT_SIZE, 380, Short.MAX_VALUE)
                    .addGroup(layout.createSequentialGroup()
                        .addComponent(lblInfo)
                        .addGap(0, 0, Short.MAX_VALUE)))
                .addContainerGap())
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
                .addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                .addComponent(lblInfo)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                .addComponent(scrollPane, javax.swing.GroupLayout.PREFERRED_SIZE, 254, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addContainerGap())
        );

        pack();
    }                      

    /**
     * @param args the command line arguments
     */
    public static void main(String args[]) {
        /* Create and display the form */
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                new ChildJFrame().setVisible(true);
            }
        });
    }
    // Variables declaration - do not modify                     
    private javax.swing.JLabel lblInfo;
    private javax.swing.JScrollPane scrollPane;
    private javax.swing.JTextArea textArea;
    // End of variables declaration                   

    /**
     * Getter Method
     * @return the textArea
     */
    public javax.swing.JTextArea getTextArea() {
        return textArea;
    }

    /**
     * Setter Method
     * @param textArea the textArea to set
     */
    public void setTextArea(javax.swing.JTextArea textArea) {
        this.textArea = textArea;
    }
}

Tags: How to , Swing