Using JNA SetForeGroundWindow

Question

at the moment I'm trying to use JNA to set a non-Java application into focus and I've found the following code.

import com.sun.jna.platform.win32.User32;
import com.sun.jna.platform.win32.WinDef.HWND;
public class win32functions{
    public static void setFocusToWindowsApp(String applicationTitle, int windowState) {
        int state = windowState;
            switch (state) {
            default:
            case 0:
                state = User32.SW_SHOWNORMAL;
                break;
            case 1:
                state = User32.SW_SHOWMAXIMIZED;
                break;
            case 2:
                state = User32.SW_SHOWMINIMIZED;
                break;
        }
        User32 user32 = User32.INSTANCE;
        HWND hWnd = user32.FindWindow(null, applicationTitle);
        if (user32.IsWindowVisible(hWnd)) {
            if (state != User32.SW_SHOWMINIMIZED) {
                user32.ShowWindow(hWnd, User32.SW_SHOWMINIMIZED);
            }
            user32.ShowWindow(hWnd, state);
            user32.SetFocus(hWnd);
        }
    }
}

I also put the following dependencies into my pom.xml, the project is a fresh one with only a main file.

<properties>
<jna.version>5.5.0</jna.version>
</properties>


<dependencies>
<dependency>
    <groupId>net.java.dev.jna</groupId>
    <artifactId>jna</artifactId>
    <version>${jna.version}</version>
</dependency>
<dependency>
    <groupId>net.java.dev.jna</groupId>
    <artifactId>jna-platform</artifactId>
    <version>${jna.version}</version>
</dependency>
</dependencies>

This is our Programm entry point:

public class EntryPoint{

    public static void main(String[] args) throws Exception
    {
          win32functions.setFocusToWindowsApp("Google Chrome", 0);
    }
}

In theory, on compilation/run the Programm should just focus Google Chrome, which is opened while running.

However, Java gives the following error message:

Exception in thread "main" java.lang.NoSuchMethodError: 'com.sun.jna.Library com.sun.jna.Native.load(java.lang.String, java.lang.Class, java.util.Map)'
at com.sun.jna.platform.win32.User32.<clinit>(User32.java:49)
at win32functions.setFocusToWindowsApp(win32functions.java:21)
at EntryPoint.main(EntryPoint.java:16)

The only reference that I've found towards this problem was this NoSuchMethodError using JNA User32 platform map

It was almost the same error and the solution was to just change the version of JNA and JNA-platform. However, in my Maven Dependencies im using the same version for both platform and JNA. Can someone give me some insight? I'm actually really desperate, that's why I'm asking here.

score 1 · Accepted Answer · answered Jan 06 '20 at 17:57

The exception points to the same immediate error cause that your linked question had, specifically, your project can not find the JNA 5.x version of the Native class (with the load(String, Class, Map) method), suggesting you have an older version of the com.sun.jna.Native class on your classpath.

It looks like you've already suspected this, and your pom.xml excerpt looks correct in isolation, but you haven't given enough context to know whether there's another common error that's causing the wrong version to be loaded. One of the following actions should help solve your problem:

Make sure you've listed the jna and jna-platform dependencies first in the highest level pom.xml file in your project. If you have any other dependencies which transitively load an earlier version of JNA, they may be processing them first.
Make sure you have executed a command to update/refresh/reload the project dependencies based on the latest pom.xml file.
- If you're using the command line, mvn install or mvn package should accomplish this.
- If you're using an IDE, look for a menu command to accomplish this. For example, in Eclipse, you need to use Maven > Update Project.
Make sure you haven't manually specified any other jar/package on your classpath (especially outside of Maven) that includes the older Native.jar. Spring Boot is a common culprit here.
Try deleting your maven repository cache and letting it rebuild, in case you have an older cached version and the update is failing for some reason.

Using JNA SetForeGroundWindow

1 Answers1