Don't crash the other experimental apps

Don't try to find the class org.libreoffice.experimental.desktop.Desktop in
the AndroidSalInstance constructor. It won't exist anyway except in that
specific app. Look up the class in the damaged() method where it is needed.

And actually, of course we should not hardcode the name of the app class like
that, but the app should pass its class down to the native code.

Change-Id: Ic15d5cc2c8d53be558711ca7a145d5489e34d298

vcl/android/androidinst.cxx

@@ -157,11 +157,30 @@ void AndroidSalInstance::RedrawWindows(ANativeWindow *pWindow, ANativeWindow_Buf
 
 void AndroidSalInstance::damaged(AndroidSalFrame */* frame */)
 {
+    static bool beenHere = false;
+    static jclass nDesktopClass = 0;
+    static jmethodID nCallbackDamaged = 0;
+
+    // Check if we are running in the experimental Desktop app
+    if (!beenHere) {
+        nDesktopClass = m_pJNIEnv->FindClass("org/libreoffice/experimental/desktop/Desktop");
+        if (nDesktopClass == 0) {
+            LOGI("Could not find Desktop class (this is normal if this isn't the \"desktop\" app)");
+            // We don't want the exception to kill the app
+            m_pJNIEnv->ExceptionClear();
+        } else {
+            nCallbackDamaged = m_pJNIEnv->GetStaticMethodID(nDesktopClass, "callbackDamaged", "()V");
+            if (nCallbackDamaged == 0)
+                LOGE("Could not find the callbackDamaged method");
+        }
+        beenHere = true;
+    }
+
     // Call the Java layer to post an invalidate if necessary
     // static public void org.libreoffice.experimental.desktop.Desktop.callbackDamaged();
 
-    if (m_nDesktopClass != 0 && m_nCallbackDamaged != 0)
-        m_pJNIEnv->CallStaticVoidMethod(m_nDesktopClass, m_nCallbackDamaged);
+    if (nDesktopClass != 0 && nCallbackDamaged != 0)
+        m_pJNIEnv->CallStaticVoidMethod(nDesktopClass, nCallbackDamaged);
 }
 
 void AndroidSalInstance::GetWorkArea( Rectangle& rRect )
@@ -209,15 +228,6 @@ AndroidSalInstance::AndroidSalInstance( SalYieldMutex *pMutex )
     int res = (lo_get_javavm())->AttachCurrentThread(&m_pJNIEnv, NULL);
     LOGI("AttachCurrentThread res=%d env=%p", res, m_pJNIEnv);
 
-    m_nDesktopClass = m_pJNIEnv->FindClass("org/libreoffice/experimental/desktop/Desktop");
-    if (m_nDesktopClass == 0)
-        LOGE("Could not find Desktop class");
-    else {
-        m_nCallbackDamaged = m_pJNIEnv->GetStaticMethodID(m_nDesktopClass, "callbackDamaged", "()V");
-        if (m_nCallbackDamaged == 0)
-            LOGE("Could not find the callbackDamaged method");
-    }
-
     LOGI("created Android Sal Instance thread: %d",
          (int)pthread_self());
 }

vcl/inc/android/androidinst.hxx

@@ -47,11 +47,6 @@ class AndroidSalInstance : public SvpSalInstance
     // in which soffice_main() runs
     JNIEnv *m_pJNIEnv;
 
-    // The Desktop class
-    jclass m_nDesktopClass;
-
-    jmethodID m_nCallbackDamaged;
-
 public:
     AndroidSalInstance( SalYieldMutex *pMutex );
     virtual ~AndroidSalInstance();