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Dialogs in Java SWT

Dialogs

In this part of the Java SWT tutorial, we will introduce dialogs.
Dialog windows or dialogs are an indispensable part of most modern GUI applications. A dialog is defined as a conversation between two or more persons. In a computer application a dialog is a window which is used to "talk" to the application. A dialog is used to input data, modify data, change the application settings etc. Dialogs are important means of communication between a user and a computer program.

Directory dialog

The directory dialog is a dialog, which is used to select a path to a certain directory. 
package com.zetcode;

import org.eclipse.swt.SWT;
import org.eclipse.swt.events.MouseAdapter;
import org.eclipse.swt.events.MouseEvent;
import org.eclipse.swt.layout.FormAttachment;
import org.eclipse.swt.layout.FormData;
import org.eclipse.swt.layout.FormLayout;
import org.eclipse.swt.widgets.DirectoryDialog;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Label;
import org.eclipse.swt.widgets.Shell;

/**
 * ZetCode Java SWT tutorial
 *
 * This example shows a directory dialog
 *
 * @author jan bodnar
 * website zetcode.com
 * last modified June 2009
 */

public class SWTApp {

    private Shell shell;

    public SWTApp(Display display) {

        shell = new Shell(display);

        shell.setText("DirectoryDialog");

        initUI();

        shell.setSize(350, 250);
        shell.setLocation(300, 300);

        shell.open();

        while (!shell.isDisposed()) {
          if (!display.readAndDispatch()) {
            display.sleep();
          }
        }
    }


    public void initUI() {


        final Label status = new Label(shell, SWT.BORDER);
        status.setText("Ready");
        FormLayout layout = new FormLayout();
        shell.setLayout(layout);

        FormData labelData = new FormData();
        labelData.left = new FormAttachment(0);
        labelData.right = new FormAttachment(100);
        labelData.bottom = new FormAttachment(100);
        status.setLayoutData(labelData);

        shell.addMouseListener(new MouseAdapter() {

            @Override
            public void mouseDown(MouseEvent event) {
                DirectoryDialog dialog = new DirectoryDialog(shell);
                String path = dialog.open();
                if (path != null)
                    status.setText(path);
            }

        });
    }


    public static void main(String[] args) {
        Display display = new Display();
        new SWTApp(display);
        display.dispose();
    }
}
In our example, we use the directory dialog to select a directory. The path to the directory is shown in the status label. The dialog is shown by clicking on the area of the window. 
DirectoryDialog dialog = new DirectoryDialog(shell);
DirectoryDialog is created. 
String path = dialog.open();
We get the path to the selected directory. 
if (path != null)
    status.setText(path);
If the path is not null, we show the path in the status label.
Directory dialog
Figure: Directory dialog

FontDialog

The FontDialog is a dialog for selecting fonts. It is typically used in applications, that do some text editing or formatting. 
package com.zetcode;

import org.eclipse.swt.SWT;
import org.eclipse.swt.events.MouseAdapter;
import org.eclipse.swt.events.MouseEvent;
import org.eclipse.swt.graphics.Font;
import org.eclipse.swt.graphics.FontData;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.FontDialog;
import org.eclipse.swt.widgets.Label;
import org.eclipse.swt.widgets.Shell;

/**
 * ZetCode Java SWT tutorial
 *
 * This example shows a font dialog
 *
 * @author jan bodnar
 * website zetcode.com
 * last modified June 2009
 */

public class SWTApp {

    private Shell shell;

    public SWTApp(Display display) {

        shell = new Shell(display);

        shell.setText("FontDialog");

        initUI();

        shell.setSize(350, 250);
        shell.setLocation(300, 300);

        shell.open();

        while (!shell.isDisposed()) {
            if (!display.readAndDispatch()) {
                display.sleep();
            }
        }
    }

    public void initUI() {


        final Label label = new Label(shell, SWT.NONE);
        label.setText("ZetCode Java SWT tutorial");

        label.setLocation(50, 50);
        label.pack();


        shell.addMouseListener(new MouseAdapter() {

            @Override
            public void mouseDown(MouseEvent event) {
                FontDialog dialog = new FontDialog(shell);
                FontData fdata = dialog.open();

                if (fdata != null) {

                    Font font = new Font(shell.getDisplay(), fdata);
                
                    label.setFont(font);
                    label.pack();
                    font.dispose();
                }                
            }
        });
    }

    public static void main(String[] args) {
        Display display = new Display();
        new SWTApp(display);
        display.dispose();
    }
}
In the code example, we use a FontDialog to change the font of a label. 
FontDialog dialog = new FontDialog(shell);
We create the FontDialog. 
Font font = new Font(shell.getDisplay(), fdata);
Font object is created from the font data, returned by the font dialog.
FontDialog
Figure: FontDialog

ColorDialog

ColorDialog is a dialog for selecting a color. 
package com.zetcode;

import org.eclipse.swt.SWT;
import org.eclipse.swt.events.MouseAdapter;
import org.eclipse.swt.events.MouseEvent;
import org.eclipse.swt.graphics.Color;
import org.eclipse.swt.graphics.RGB;
import org.eclipse.swt.widgets.ColorDialog;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Label;
import org.eclipse.swt.widgets.Shell;

/**
 * ZetCode Java SWT tutorial
 *
 * This example shows a color dialog
 *
 * @author jan bodnar
 * website zetcode.com
 * last modified June 2009
 */

public class SWTApp {

    private Shell shell;

    public SWTApp(Display display) {

        shell = new Shell(display);

        shell.setText("ColorDialog");

        initUI();

        shell.setSize(350, 250);
        shell.setLocation(300, 300);

        shell.open();

        while (!shell.isDisposed()) {
          if (!display.readAndDispatch()) {
            display.sleep();
          }
        }
    }


    public void initUI() {


        final Label label = new Label(shell, SWT.NONE);
        label.setText("ZetCode Java SWT tutorial");

        label.setLocation(50, 50);
        label.pack();


        shell.addMouseListener(new MouseAdapter() {

            @Override
            public void mouseDown(MouseEvent event) {
                ColorDialog dialog = new ColorDialog(shell);
                RGB rgb = dialog.open();
                if (rgb != null) {
                    Color col = new Color(shell.getDisplay(), rgb);
                    label.setForeground(col);
                    col.dispose();
                }
            }

        });
    }


    public static void main(String[] args) {
        Display display = new Display();
        new SWTApp(display);
        display.dispose();
    }
}
The example is very similar to the previous one. This time we change the color of the label. 
ColorDialog dialog = new ColorDialog(shell);
We create the ColorDialog. 
RGB rgb = dialog.open();
We get the RGB value. 
Color col = new Color(shell.getDisplay(), rgb);
label.setForeground(col);
We get the color value and modify the color of the label.
ColorDialog
Figure: ColorDialog

FileDialog

The FileDialog is used to select a name of a file. 
package com.zetcode;

import org.eclipse.swt.SWT;
import org.eclipse.swt.events.MouseAdapter;
import org.eclipse.swt.events.MouseEvent;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.FileDialog;
import org.eclipse.swt.widgets.Label;
import org.eclipse.swt.widgets.Shell;

/**
 * ZetCode Java SWT tutorial
 *
 * This example shows a file dialog
 *
 * @author jan bodnar
 * website zetcode.com
 * last modified June 2009
 */

public class SWTApp {

    private Shell shell;

    public SWTApp(Display display) {

        shell = new Shell(display);

        shell.setText("FileDialog");

        initUI();

        shell.setSize(350, 250);
        shell.setLocation(300, 300);

        shell.open();

        while (!shell.isDisposed()) {
          if (!display.readAndDispatch()) {
            display.sleep();
          }
        }
    }


    public void initUI() {


        final Label label = new Label(shell, SWT.NONE);
        label.setText("ZetCode Java SWT tutorial");

        label.setLocation(50, 50);
        label.pack();


        shell.addMouseListener(new MouseAdapter() {

            @Override
            public void mouseDown(MouseEvent event) {
                FileDialog dialog = new FileDialog(shell, SWT.OPEN);

                String[] filterNames = new String[] 
                    {"Java sources", "All Files (*)"};

                String[] filterExtensions = new String[] 
                    {"*.java", "*"};

                dialog.setFilterNames(filterNames);
                dialog.setFilterExtensions(filterExtensions);

                String path = dialog.open();
                if (path != null) {
                    label.setText(path);
                    label.pack();
                }
            }
        });
    }


    public static void main(String[] args) {
        Display display = new Display();
        new SWTApp(display);
        display.dispose();
    }
}
The code example uses a FileDialog to select a file. The dialog uses a filter to show only the java sources. The name of the file is shown in the label. 
FileDialog dialog = new FileDialog(shell, SWT.OPEN);
We create an FileDialog with a SWT.OPEN flag. The dialog can be used to open or save files. 
String[] filterNames = new String[] 
{"Java sources", "All Files (*)"};

String[] filterExtensions = new String[] 
    {"*.java", "*"};

dialog.setFilterNames(filterNames);
dialog.setFilterExtensions(filterExtensions);
We use a filter to narrow the files to Java sources.
This part of the Java SWT tutorial was about dialogs in SWT.
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