Use typed AndroidX fragment stubs

Author: 8Keep

jme3-android/src/androidx-stubs/java/androidx/fragment/app/FragmentActivity.java

@@ -40,4 +40,8 @@
  * application. This class is excluded from jme3-android artifacts.</p>
  */
 public class FragmentActivity extends Activity {
+
+    public FragmentManager getSupportFragmentManager() {
+        return null;
+    }
 }

jme3-android/src/androidx-stubs/java/androidx/fragment/app/FragmentManager.java

@@ -0,0 +1,49 @@
+/*
+ * Copyright (c) 2009-2026 jMonkeyEngine
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ * * Redistributions of source code must retain the above copyright
+ *   notice, this list of conditions and the following disclaimer.
+ *
+ * * Redistributions in binary form must reproduce the above copyright
+ *   notice, this list of conditions and the following disclaimer in the
+ *   documentation and/or other materials provided with the distribution.
+ *
+ * * Neither the name of 'jMonkeyEngine' nor the names of its contributors
+ *   may be used to endorse or promote products derived from this software
+ *   without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+ * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+package androidx.fragment.app;
+
+/**
+ * Compile-time stub for the AndroidX FragmentManager API.
+ *
+ * <p>The real AndroidX Fragment dependency must be supplied by the Android
+ * application. This class is excluded from jme3-android artifacts.</p>
+ */
+public class FragmentManager {
+
+    public Fragment findFragmentByTag(String tag) {
+        return null;
+    }
+
+    public FragmentTransaction beginTransaction() {
+        return null;
+    }
+}

jme3-android/src/androidx-stubs/java/androidx/fragment/app/FragmentTransaction.java

@@ -0,0 +1,49 @@
+/*
+ * Copyright (c) 2009-2026 jMonkeyEngine
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ * * Redistributions of source code must retain the above copyright
+ *   notice, this list of conditions and the following disclaimer.
+ *
+ * * Redistributions in binary form must reproduce the above copyright
+ *   notice, this list of conditions and the following disclaimer in the
+ *   documentation and/or other materials provided with the distribution.
+ *
+ * * Neither the name of 'jMonkeyEngine' nor the names of its contributors
+ *   may be used to endorse or promote products derived from this software
+ *   without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+ * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+package androidx.fragment.app;
+
+/**
+ * Compile-time stub for the AndroidX FragmentTransaction API.
+ *
+ * <p>The real AndroidX Fragment dependency must be supplied by the Android
+ * application. This class is excluded from jme3-android artifacts.</p>
+ */
+public class FragmentTransaction {
+
+    public FragmentTransaction replace(int containerViewId, Fragment fragment, String tag) {
+        return this;
+    }
+
+    public int commit() {
+        return 0;
+    }
+}

jme3-android/src/main/java/com/jme3/app/AndroidHarness.java

@@ -44,7 +44,9 @@
 import android.view.WindowManager;
 import android.widget.FrameLayout;
 import android.widget.ImageView;
+import androidx.fragment.app.Fragment;
 import androidx.fragment.app.FragmentActivity;
+import androidx.fragment.app.FragmentManager;
 import com.jme3.audio.AudioRenderer;
 import com.jme3.input.JoyInput;
 import com.jme3.input.TouchInput;
@@ -58,7 +60,6 @@
 import com.jme3.system.android.OGLESContext;
 import java.io.PrintWriter;
 import java.io.StringWriter;
-import java.lang.reflect.Method;
 import java.util.logging.Level;
 import java.util.logging.Logger;
 
@@ -112,15 +113,14 @@ public class AndroidHarness extends FragmentActivity
     protected ImageView splashImageView;
     protected FrameLayout frameLayout;
 
-    private HarnessFragment fragment;
     private boolean firstDrawFrame = true;
 
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         configureWindow();
 
-        fragment = attachFragment();
+        HarnessFragment fragment = attachFragment();
         fragment.setFinishOnAppStop(finishOnAppStop);
     }
 
@@ -139,26 +139,17 @@ public Application getJmeApplication() {
     }
 
     private HarnessFragment attachFragment() {
-        try {
-            Method getSupportFragmentManager = getClass().getMethod("getSupportFragmentManager");
-            Object fragmentManager = getSupportFragmentManager.invoke(this);
-            Object existingFragment = fragmentManager.getClass()
-                    .getMethod("findFragmentByTag", String.class)
-                    .invoke(fragmentManager, HARNESS_FRAGMENT_TAG);
-            if (existingFragment instanceof HarnessFragment) {
-                return (HarnessFragment) existingFragment;
-            }
-
-            HarnessFragment newFragment = new HarnessFragment();
-            Object transaction = fragmentManager.getClass().getMethod("beginTransaction").invoke(fragmentManager);
-            transaction = transaction.getClass()
-                    .getMethod("replace", int.class, androidx.fragment.app.Fragment.class, String.class)
-                    .invoke(transaction, android.R.id.content, newFragment, HARNESS_FRAGMENT_TAG);
-            transaction.getClass().getMethod("commit").invoke(transaction);
-            return newFragment;
-        } catch (ReflectiveOperationException exception) {
-            throw new IllegalStateException("Unable to attach AndroidHarnessFragment", exception);
+        FragmentManager fragmentManager = getSupportFragmentManager();
+        Fragment existingFragment = fragmentManager.findFragmentByTag(HARNESS_FRAGMENT_TAG);
+        if (existingFragment instanceof HarnessFragment) {
+            return (HarnessFragment) existingFragment;
         }
+
+        HarnessFragment newFragment = new HarnessFragment();
+        fragmentManager.beginTransaction()
+                .replace(android.R.id.content, newFragment, HARNESS_FRAGMENT_TAG)
+                .commit();
+        return newFragment;
     }
 
     @Override