commit 74d9fe799e2cba556a9f723a826fd6e0c9f3679e
author Edwin Kempin <ekempin@google.com> Mon Apr 11 17:45:04 2016 +0200
committer Edwin Kempin <ekempin@google.com> Mon Apr 11 17:45:04 2016 +0200
tree dbf21f254892586ecb97a3e0d712bd63269452d2
parent 8b48c935b453e59633b6a92abf065ee1680c7644

Fix back navigation from initial fragment

Clicking on the hardware back button while the initial fragment was
shown resulted in showing an empty screen and only on a second click
the app was moved to the background.

This was because the initial fragment was wrongly added to the back
stack.

Change-Id: I482842b8a578c715ce5ee0d1396b3e683d098b16
Signed-off-by: Edwin Kempin <ekempin@google.com>

app/src/main/java/com/google/reviewit/MainActivity.java

diff --git a/app/src/main/java/com/google/reviewit/MainActivity.java b/app/src/main/java/com/google/reviewit/MainActivity.java
index 4960f72..13705fd 100644
--- a/app/src/main/java/com/google/reviewit/MainActivity.java
+++ b/app/src/main/java/com/google/reviewit/MainActivity.java
@@ -22,6 +22,7 @@
 import android.support.annotation.StringRes;
 import android.support.v4.app.Fragment;
 import android.support.v4.app.FragmentManager;
+import android.support.v4.app.FragmentTransaction;
 import android.support.v4.widget.DrawerLayout;
 import android.support.v7.app.ActionBarDrawerToggle;
 import android.support.v7.widget.Toolbar;
@@ -139,15 +140,15 @@
     });
 
     if (getApp().getPrefs().showIntro) {
-      displayView(new IntroFragment1());
+      displayInitialView(new IntroFragment1());
     } else if (savedInstanceState == null) {
       switch (getApp().getPrefs().startScreen) {
         case REVIEW_SCREEN:
-          displayView(1);
+          displayInitialView(newFragmentInstance(items.get(1).fragmentClass));
           break;
         case SORT_SCREEN:
         default:
-          displayView(0);
+          displayInitialView(newFragmentInstance(items.get(0).fragmentClass));
           break;
       }
     }
@@ -173,12 +174,24 @@
     drawer.closeDrawer(list);
   }
 
+  private void displayInitialView(Fragment fragment) {
+    displayView(fragment, false);
+  }
+
   private void displayView(Fragment fragment) {
+    displayView(fragment, true);
+  }
+
+  private void displayView(Fragment fragment, boolean addToBackStack) {
     FragmentManager fragmentManager = getSupportFragmentManager();
-    fragmentManager.beginTransaction()
-        .replace(R.id.mainFrame, fragment)
-        .addToBackStack(null)
-        .commit();
+    FragmentTransaction t = fragmentManager.beginTransaction()
+        .replace(R.id.mainFrame, fragment);
+
+    if (addToBackStack) {
+      t.addToBackStack(null);
+    }
+
+    t.commit();
   }
 
   private Fragment newFragmentInstance(