Prevent crashes and related issues if initial activity is destroyed on Android

* java/org/gnu/emacs/EmacsWindow.java
(EmacsWindow) <initialWindowCreated>: New variable.
(EmacsWindow): If the initial frame has not yet been created,
set attachmentToken to -1.

* java/org/gnu/emacs/EmacsWindowManager.java (registerWindow):
When the window's attachment token is -1 (i.e., it is the
default window), start EmacsActivity rather than
EmacsMultitaskActivity.  Catch exceptions around startActivity.

2 files changed, 47 insertions, 7 deletions

diff --git a/java/org/gnu/emacs/EmacsWindow.java b/java/org/gnu/emacs/EmacsWindow.java
index 0a4d04971e7..218c5639c89 100644
--- a/java/org/gnu/emacs/EmacsWindow.java
+++ b/java/org/gnu/emacs/EmacsWindow.java
@@ -74,6 +74,9 @@ public final class EmacsWindow extends EmacsHandleObject
 {
   private static final String TAG = "EmacsWindow";
 
+  /* Whether any windows have yet been created in this session.  */
+  private static boolean initialWindowCreated;
+
   private static class Coordinate
   {
     /* Integral coordinate.  */
@@ -192,6 +195,14 @@ public final class EmacsWindow extends EmacsHandleObject
     this.parent = parent;
     this.overrideRedirect = overrideRedirect;
 
+    /* The initial frame should always be bound to the startup
+       activity.  */
+    if (!initialWindowCreated)
+      {
+        this.attachmentToken = -1;
+        initialWindowCreated = true;
+      }
+
     /* Create the list of children.  */
     children = new ArrayList<EmacsWindow> ();
 
diff --git a/java/org/gnu/emacs/EmacsWindowManager.java b/java/org/gnu/emacs/EmacsWindowManager.java
index 03487e853fb..e4bd995f15a 100644
--- a/java/org/gnu/emacs/EmacsWindowManager.java
+++ b/java/org/gnu/emacs/EmacsWindowManager.java
@@ -174,6 +174,27 @@ public final class EmacsWindowManager
           }
       }
 
+    /* Do not create a multitasking activity for the initial frame,
+       but arrange to start EmacsActivity.  */
+    if (window.attachmentToken == -1)
+      {
+        intent = new Intent (EmacsService.SERVICE,
+                             EmacsActivity.class);
+        intent.addFlags (Intent.FLAG_ACTIVITY_NEW_TASK);
+
+        try
+          {
+            EmacsService.SERVICE.startActivity (intent);
+          }
+        catch (Exception e)
+          {
+            Log.w (TAG, "an activity could not be started on behalf"
+                   + " of the mapped default window " + window.handle);
+          }
+
+        return;
+      }
+
     intent = new Intent (EmacsService.SERVICE,
                          EmacsMultitaskActivity.class);
 
@@ -205,14 +226,22 @@ public final class EmacsWindowManager
     window.attachmentToken = token;
     intent.putExtra (ACTIVITY_TOKEN, token);
 
-    if (Build.VERSION.SDK_INT < Build.VERSION_CODES.N)
-      EmacsService.SERVICE.startActivity (intent);
-    else
+    try
+      {
+        if (Build.VERSION.SDK_INT < Build.VERSION_CODES.N)
+          EmacsService.SERVICE.startActivity (intent);
+        else
+          {
+            /* Specify the desired window size.  */
+            options = ActivityOptions.makeBasic ();
+            options.setLaunchBounds (window.getGeometry ());
+            EmacsService.SERVICE.startActivity (intent, options.toBundle ());
+          }
+      }
+    catch (Exception e)
       {
-        /* Specify the desired window size.  */
-        options = ActivityOptions.makeBasic ();
-        options.setLaunchBounds (window.getGeometry ());
-        EmacsService.SERVICE.startActivity (intent, options.toBundle ());
+        Log.w (TAG, "an activity could not be started on behalf"
+               + " of a mapped window, " + window.handle);
       }
 
     pruneWindows ();