Merge branch '1707-fragment-listeners' into 'master'

Don't overwrite listener references with null during fragment changes

Closes #1707, #1706, #1704, and #1697

See merge request briar/briar!1227

briar-android/src/main/java/org/briarproject/briar/android/blog/BlogController.java

@@ -9,7 +9,6 @@ import org.briarproject.briar.android.controller.handler.ResultExceptionHandler;
 
 import java.util.Collection;
 
-import androidx.annotation.Nullable;
 import androidx.annotation.UiThread;
 
 @NotNullByDefault
@@ -18,7 +17,10 @@ public interface BlogController extends BaseController {
 	void setGroupId(GroupId g);
 
 	@UiThread
-	void setBlogSharingListener(@Nullable BlogSharingListener listener);
+	void setBlogSharingListener(BlogSharingListener listener);
+
+	@UiThread
+	void unsetBlogSharingListener(BlogSharingListener listener);
 
 	void loadBlogPosts(
 			ResultExceptionHandler<Collection<BlogPostItem>, DbException> handler);

briar-android/src/main/java/org/briarproject/briar/android/blog/BlogControllerImpl.java

@@ -96,10 +96,15 @@ class BlogControllerImpl extends BaseControllerImpl
 	}
 
 	@Override
-	public void setBlogSharingListener(@Nullable BlogSharingListener listener) {
+	public void setBlogSharingListener(BlogSharingListener listener) {
 		this.listener = listener;
 	}
 
+	@Override
+	public void unsetBlogSharingListener(BlogSharingListener listener) {
+		if (this.listener == listener) this.listener = null;
+	}
+
 	@Override
 	public void eventOccurred(Event e) {
 		if (groupId == null || listener == null)

briar-android/src/main/java/org/briarproject/briar/android/blog/BlogFragment.java

@@ -141,7 +141,8 @@ public class BlogFragment extends BaseFragment
 	@Override
 	public void onDestroy() {
 		super.onDestroy();
-		blogController.setBlogSharingListener(null);
+		blogController.unsetBlogSharingListener(this);
+		sharingController.unsetSharingListener(this);
 	}
 
 	@Override

briar-android/src/main/java/org/briarproject/briar/android/blog/FeedController.java

@@ -7,7 +7,6 @@ import org.briarproject.briar.api.blog.Blog;
 
 import java.util.Collection;
 
-import androidx.annotation.Nullable;
 import androidx.annotation.UiThread;
 
 @NotNullByDefault
@@ -19,7 +18,10 @@ public interface FeedController extends BaseController {
 	void loadPersonalBlog(ResultExceptionHandler<Blog, DbException> handler);
 
 	@UiThread
-	void setFeedListener(@Nullable FeedListener listener);
+	void setFeedListener(FeedListener listener);
+
+	@UiThread
+	void unsetFeedListener(FeedListener listener);
 
 	@NotNullByDefault
 	interface FeedListener extends BlogListener {

briar-android/src/main/java/org/briarproject/briar/android/blog/FeedControllerImpl.java

@@ -69,10 +69,15 @@ class FeedControllerImpl extends BaseControllerImpl implements FeedController {
 	}
 
 	@Override
-	public void setFeedListener(@Nullable FeedListener listener) {
+	public void setFeedListener(FeedListener listener) {
 		this.listener = listener;
 	}
 
+	@Override
+	public void unsetFeedListener(FeedListener listener) {
+		if (this.listener == listener) this.listener = null;
+	}
+
 	@Override
 	public void eventOccurred(Event e) {
 		if (listener == null) throw new IllegalStateException();

briar-android/src/main/java/org/briarproject/briar/android/blog/FeedFragment.java

@@ -134,7 +134,7 @@ public class FeedFragment extends BaseFragment implements
 	@Override
 	public void onDestroy() {
 		super.onDestroy();
-		feedController.setFeedListener(null);
+		feedController.unsetFeedListener(this);
 	}
 
 	@Override

briar-android/src/main/java/org/briarproject/briar/android/controller/SharingController.java

@@ -16,6 +16,12 @@ public interface SharingController {
 	@UiThread
 	void setSharingListener(SharingListener listener);
 
+	/**
+	 * Unsets the listener.
+	 */
+	@UiThread
+	void unsetSharingListener(SharingListener listener);
+
 	/**
 	 * Call this when your lifecycle starts,
 	 * so the listener will be called when information changes.

briar-android/src/main/java/org/briarproject/briar/android/controller/SharingControllerImpl.java

@@ -43,6 +43,11 @@ public class SharingControllerImpl implements SharingController, EventListener {
 		this.listener = listener;
 	}
 
+	@Override
+	public void unsetSharingListener(SharingListener listener) {
+		if (this.listener == listener) this.listener = null;
+	}
+
 	@Override
 	public void onStart() {
 		eventBus.addListener(this);

briar-android/src/main/java/org/briarproject/briar/android/privategroup/list/GroupListController.java

@@ -10,8 +10,6 @@ import org.briarproject.briar.api.privategroup.GroupMessageHeader;
 
 import java.util.Collection;
 
-import javax.annotation.Nullable;
-
 import androidx.annotation.UiThread;
 
 @NotNullByDefault
@@ -21,7 +19,10 @@ interface GroupListController extends DbController {
 	 * The listener must be set right after the controller was injected
 	 */
 	@UiThread
-	void setGroupListListener(@Nullable GroupListListener listener);
+	void setGroupListListener(GroupListListener listener);
+
+	@UiThread
+	void unsetGroupListListener(GroupListListener listener);
 
 	@UiThread
 	void onStart();

briar-android/src/main/java/org/briarproject/briar/android/privategroup/list/GroupListControllerImpl.java

@@ -80,10 +80,15 @@ class GroupListControllerImpl extends DbControllerImpl
 	}
 
 	@Override
-	public void setGroupListListener(@Nullable GroupListListener listener) {
+	public void setGroupListListener(GroupListListener listener) {
 		this.listener = listener;
 	}
 
+	@Override
+	public void unsetGroupListListener(GroupListListener listener) {
+		if (this.listener == listener) this.listener = null;
+	}
+
 	@Override
 	@CallSuper
 	public void onStart() {

briar-android/src/main/java/org/briarproject/briar/android/privategroup/list/GroupListFragment.java

@@ -112,7 +112,7 @@ public class GroupListFragment extends BaseFragment implements
 	@Override
 	public void onDestroy() {
 		super.onDestroy();
-		controller.setGroupListListener(null);
+		controller.unsetGroupListListener(this);
 	}
 
 	@Override