SWT: Composite widget

A Composite widget can contain other widgets, the way how you are adding widgets to shell, you can add widgets to Composite.

How to define a Composite?

Composite composite1 = new Composite(shell,SWT.BORDER);

How to add widgets to a composite?

Just like how you are adding widgets to Shell, you can add widgets to composite also.

Label label = new Label(composite1,SWT.NONE);

The position of widgets inside the composite are relative to the composite. You can apply following styles to Composite widget.

Widget	Description
NO_BACKGROUND	Style constant for no background behavior
NO_FOCUS	Style constant for no focus from the mouse behavior
NO_MERGE_PAINTS	Style constant for no paint event merging behavior
NO_REDRAW_RESIZE	Style constant for no redraw on resize behavior
NO_RADIO_GROUP	Style constant for preventing child radio group behavior
EMBEDDED	Style constant to allow embedding
DOUBLE_BUFFERED	Style constant to indicate double buffering

package swt_app;

import org.eclipse.swt.SWT;
import org.eclipse.swt.events.SelectionAdapter;
import org.eclipse.swt.events.SelectionEvent;
import org.eclipse.swt.graphics.Color;
import org.eclipse.swt.widgets.Button;
import org.eclipse.swt.widgets.Combo;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Shell;

public class Test {

 private static int xPosition = 30;
 private static int yPosition = 30;

 private static int shellWidth = 600;
 private static int shellHeight = 600;

 private static int compositeWidth = 250;
 private static int compositeHeight = 250;

 private static String[] countries = { "India", "Germany", "Canada", "Japan", "Sri Lanka", "Singpore", "Russia" };

 private static void addWidgetsToShell(Display display, Shell shell) {

  Composite composite = new Composite(shell, SWT.BORDER);
  composite.setBackground(new Color(display, 102, 153, 153));
  composite.setBounds(10, 10, compositeWidth, compositeHeight);

  Combo combo = new Combo(composite, SWT.DROP_DOWN);
  combo.setItems(countries);
  combo.setBounds(xPosition, 20, 150, 100);
  combo.setText("Select your country");

  yPosition += 100;

  Button button1 = new Button(composite, SWT.PUSH);
  button1.setText("Submit");
  button1.setLocation(xPosition + 100, yPosition);
  button1.setSize(100, 20);

  button1.addSelectionListener(new SelectionAdapter() {
   public void widgetSelected(SelectionEvent e) {
    System.out.println("Country Selected is : " + countries[combo.getSelectionIndex()]);
   }
  });

 }

 public static void main(String[] args) {

  /* Instantiate Display object, it represents SWT session */
  Display display = new Display();

  /*
   * Define Shell, it represent a window, You can add more than one shell
   * to Display
   */
  Shell shell = new Shell(display);
  shell.setSize(shellWidth, shellHeight);

  addWidgetsToShell(display, shell);

  /* Open shell window */
  shell.open();

  /*
   * Run the event dispatching loop until an exit condition occurs, which
   * is typically when the main shell window is closed by the user.
   */

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

  /* Dispose the display */
  display.dispose();
 }
}

Select any country and submit, you can able to see the selected country in the console.

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