Using Java to set the focus to a non Java application in Windows

Question

I would like to write an application who creates input for a non-Java application in Windows. With the Robot class it's easy to generate the input, but I need to set the focus to another application's text box and enter the text over there.

Don't worry I'm not trying to write something malicious, I just want to use Java to "extend" an old application written in Delphi.

An alternative option is that my Java application never gets the focus, so that the windows application has the focus and when you click a button on the Java application the focus is never lost in the original window. I have no idea if that's possible? — Stijn Vanpoucke, Jan 24 '11 at 13:31
for those coming to this question via google, on OSX: http://stackoverflow.com/questions/14859733/set-focus-of-any-application-with-java-osx — ericsoco, Feb 13 '13 at 18:32

score 10 · Accepted Answer · edited Feb 07 '17 at 21:36

10

CMDOW is a command line utility which allows you to perform various window actions such as activating/deactivating, listing, minimising/maximising etc.

Alternatively, you can write a VBScript to activate another application. For example:

Set WshShell = WScript.CreateObject("WScript.Shell") 
WshShell.AppActivate("Firefox")

Then use Runtime.exec from your Java app to execute the script.

This will help you activate another application.

However, it will be much more difficult if you want to focus on a textbox within the other application and write some text.

edited Feb 07 '17 at 21:36

Antoine

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answered Jan 24 '11 at 13:11

dogbane

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just have to say that I like CMDOW but I noticed 2 problems.. very slow.. on my overloaded thermal throttled system - ordering a new fan now - so for most users don't know if it will be noticeable, however nircmd worked much faster.. so just letting people know nircmd is an option too - doesn't support wildcards but you can specify if substring match or from start or from end of title. Also I couldn't get it to activate multiple windows with the same substring, nircmd could do this.. so for these 2 reasons I chose nircmd instead.. – ycomp Jan 18 '18 at 04:00
@dogbane do you know something similar for linux os? – tomm Sep 17 '18 at 11:14

score 8 · Answer 2 · edited Sep 27 '12 at 08:32

8

Configure a delay otherwise it won't work:

Robot r = new Robot();
r.keyPress(KeyEvent.VK_ALT);
r.keyPress(KeyEvent.VK_TAB);
r.delay(10); //set the delay
r.keyRelease(KeyEvent.VK_ALT);
r.keyRelease(KeyEvent.VK_TAB);

edited Sep 27 '12 at 08:32

oers

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answered Sep 27 '12 at 02:12

sreenath V

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Andreas Dolk · Answer 3 · 2011-01-24T13:12:54.780

Detecting a special application and bringing that one to the front might require a native helper, but for the moment you could send ALT+TAB to activate the "next" application

This works:

public void switchFocus() {
  try {
    Robot r = new Robot();
    r.keyPress(KeyEvent.VK_ALT);
    r.keyPress(KeyEvent.VK_TAB);
    r.keyRelease(KeyEvent.VK_ALT);
    r.keyRelease(KeyEvent.VK_TAB);
  } catch(AWTException e) {
    // handle
  }
}

you just need to implement a convenience method to map chars (from a String) to key event values... (or find some existing solution)

score 2 · Answer 4 · answered Sep 22 '17 at 14:29

On Mac, there is possible to do it with AppleScript. AppleScript is integrated to system, so it will be always functional. https://developer.apple.com/library/content/documentation/AppleScript/Conceptual/AppleScriptLangGuide/reference/ASLR_cmds.html

You need only detect you are on mac and has name of the application.

Runtime runtime = Runtime.getRuntime();
            String[] args = { "osascript", "-e", "tell app \"Chrome\" to activate" };
            Process process = runtime.exec(args);

score 0 · Answer 5 · edited May 23 '17 at 10:29

You need to add enough delay for the application to fully initialize and gain focus.

Here's a basic working example... Andreas_D is correct that you need to emulate the system key to switch between programs... (Alt+Tab on Windows, Cmd+Tab on OS X)

    import java.awt.*;
    import static java.awt.event.KeyEvent.*;
    import java.io.IOException;

    public class RobotSample {

        //https://stackoverflow.com/questions/4782231
        private static Integer[] KEY_CODES = { VK_S, VK_T, VK_A, VK_C, VK_K, VK_O, VK_V, VK_E, VK_R, VK_F, VK_L,VK_O, VK_W, VK_DECIMAL, VK_C, VK_O, VK_M, VK_SLASH, VK_Q, VK_U, VK_E, VK_S, VK_T, VK_I, VK_O, VK_N, VK_S, VK_SLASH, VK_4, VK_7, VK_8, VK_2, VK_2, VK_3, VK_1, VK_ENTER };

        public static void main( String[] args ) throws IOException {

            try {
                Robot robot = new Robot();
                Runtime runtime = Runtime.getRuntime();

                runtime.exec( "C:\\Program Files (x86)\\Google\\Chrome\\Application\\chrome.exe" );

                robot.keyPress( VK_ALT );
                robot.keyPress( VK_TAB );
                robot.keyRelease( VK_ALT );
                robot.keyRelease( VK_TAB );

                //Chill a sec...
                robot.delay( 1000 );

                for(int i = 0; i <  KEY_CODES.length; ++i) {
                    robot.keyPress( KEY_CODES[i] );
                    robot.keyRelease( KEY_CODES[i] );
                    robot.delay( 80 );
                    }

            } catch( AWTException e ) {
                e.getMessage();
            }

        }

    }

Using Java to set the focus to a non Java application in Windows

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