Example Java Call In Using Swing.

Under some circumstances your Java programs may need to call into your Uniface application. The easiest example of this is when a Uniface form component activates a Java Swing program. Swing screens are non-modal, so when the user has finished using it, or has selected a value from it, it will be necessary to activate an operation in Uniface to pass the result back:

The Java Swing program may be executed using either the activate or sql proc instructions.

To call Uniface from Java you must:

• Have the ud5.dll and the uniface 'bin' directory in your PATH
• Have compiled the MHU class and have it in your CLASSPATH
• Call the mhu.LOADLIBRARY method before calling into Uniface
• Use the UACTIVATE method from the MHU class to activate a Uniface operation. If an instance of that component is not already created, one will be created.

The source code for the MHU class is supplied with the UD5 driver. Compile it using your JDK:

javac MHU.java

Here is the example Java Swing class: HELLOSWING

Here is our example Java

//v 1.3

import javax.swing.*;    

import java.awt.*;

import java.awt.event.*;



public class HELLOSWING {

static JFrame frame;

    public static void main(String[] args) {

	HELLOSWING.EXEC();

    }

    public static int QUIT() {

      MHU mhu = new MHU();

      int res=mhu.UACTIVATE("TEST_JAVA","CLOSING_SWING","Bye");

      frame.setVisible(false);

      frame.dispose();

      return 0;

    }

    public static void EXEC() {

        MHU mhu = new MHU();

        mhu.LOADLIBRARY("ud5");



        frame = new JFrame("HelloSwing");

        final JLabel label = new JLabel("Hello World");

        frame.getContentPane().add(label);

        frame.setDefaultCloseOperation(JFrame.DO_NOTHING_ON_CLOSE);



        frame.addWindowListener(new WindowAdapter() {

            public void windowClosing(WindowEvent e) {

                int res=HELLOSWING.QUIT();

            }

        });



        frame.pack();

        frame.setVisible(true);

    }

}

Calling from SQL

This example shows how to call Java Swing using the sql proc statement :

sql "@return-type V","ud5"

sql "@static-method enable","ud5"

sql/print "HELLOSWING.EXEC","ud5"

Calling from ACTIVATE

This example shows how to call Java Swing using the activate proc statement :

activate "HELLOSWING".EXEC()

The ASN file contains this redirection:

[SERVICES_EXEC]

HELLOSWING  $MW1:HelloSwing

The Signature definition of HelloSwing is:

• Create new signature HELLOSWING using the Signature editor on the assembly workbench
• Add an operation named EXEC using the pulldown menu Go To, and the option Operations.... The Operation name is EXEC, and the literal name is EXEC. The return value is None (void).
• Add a "C" Implementation, using the pulldown menu Go To, and the option Implementations....
• Compile the signature

The CLOSING_SWING Operation

Our example Java Swing application is started from a Uniface Form Component called TEST_JAVA which has an operation named CLOSING_SWING defined:

operation CLOSING_SWING

PARAMS

  STRING TEST:IN

ENDPARAMS

PUTMESS "%%TEST"

swingres.dummy="Closed"

PUTMESS "This Worked"

macro "^next^field"

end

;

The form has a button painted which starts the Swing application, and a field named SWINGRES which contains the status indicator. NOTE: the macro in this example is to ensure the screen is correctly updated.