[android] Refactored & simplified the way default fragment activity handles fragments.

android/src/com/mapswithme/maps/base/BaseMwmFragmentActivity.java

@@ -1,6 +1,8 @@
 package com.mapswithme.maps.base;
 
 import android.os.Bundle;
+import android.support.v4.app.Fragment;
+import android.support.v4.app.FragmentTransaction;
 import android.support.v7.app.AppCompatActivity;
 import android.support.v7.widget.Toolbar;
 import android.view.MenuItem;
@@ -18,6 +20,9 @@ public class BaseMwmFragmentActivity extends AppCompatActivity
   protected void onCreate(Bundle savedInstanceState)
   {
     super.onCreate(savedInstanceState);
+    final int layoutId = getContentLayoutResId();
+    if (layoutId != 0)
+      setContentView(layoutId);
 
     // Use full-screen on Kindle Fire only
     if (Utils.isAmazonDevice())
@@ -27,6 +32,8 @@ public class BaseMwmFragmentActivity extends AppCompatActivity
     }
 
     MWMApplication.get().initStats();
+
+    attachDefaultFragment();
   }
 
   @Override
@@ -83,4 +90,56 @@ public class BaseMwmFragmentActivity extends AppCompatActivity
   {
     setSupportActionBar(getToolbar());
   }
+
+  /**
+   * Override to set custom content view.
+   * @return layout resId.
+   */
+  protected int getContentLayoutResId()
+  {
+    return 0;
+  }
+
+  protected void attachDefaultFragment()
+  {
+    final String fragmentName = getFragmentClassName();
+    if (fragmentName != null)
+      replaceFragment(getFragmentClassName(), false, getIntent().getExtras());
+  }
+
+  /**
+   * Replace attached fragment with the new one.
+   */
+  public void replaceFragment(String fragmentClassName, boolean addToBackStack, Bundle args)
+  {
+    final int resId = getFragmentContentResId();
+    if (findViewById(resId) == null)
+      throw new IllegalStateException("Fragment can't be added, since getFragmentContentResId() isn't implemented or returns wrong resourceId.");
+
+    final FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
+    final Fragment fragment = Fragment.instantiate(this, fragmentClassName, args);
+    transaction.replace(resId, fragment, fragmentClassName);
+    if (addToBackStack)
+      transaction.addToBackStack(null);
+    transaction.commit();
+  }
+
+  /**
+   * Override to automatically attach fragment in onCreate. Tag applied to fragment in back stack is set to fragment name, too.
+   * WARNING : if custom layout for activity is set, getFragmentContentResId() must be implemented, too.
+   * @return class name of the fragment, eg FragmentClass.getName()
+   */
+  protected String getFragmentClassName()
+  {
+    return null;
+  }
+
+  /**
+   * Get resource id for the fragment. That must be implemented to return correct resource id, if custom layout is set.
+   * @return resourceId for the fragment
+   */
+  protected int getFragmentContentResId()
+  {
+    return android.R.id.content;
+  }
 }

android/src/com/mapswithme/maps/bookmarks/BookmarkCategoriesActivity.java

@@ -1,8 +1,6 @@
 package com.mapswithme.maps.bookmarks;
 
 import android.os.Bundle;
-import android.support.v4.app.Fragment;
-import android.support.v4.app.FragmentTransaction;
 import android.support.v7.widget.Toolbar;
 
 import com.mapswithme.maps.R;
@@ -16,15 +14,27 @@ public class BookmarkCategoriesActivity extends BaseMwmFragmentActivity
   {
     super.onCreate(savedInstanceState);
 
-    setContentView(R.layout.activity_fragment_and_toolbar);
     final Toolbar toolbar = getToolbar();
     toolbar.setTitle(R.string.bookmark_sets);
     UiUtils.showHomeUpButton(toolbar);
     displayToolbarAsActionBar();
+  }
 
-    FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
-    Fragment fragment = Fragment.instantiate(this, BookmarkCategoriesFragment.class.getName(), getIntent().getExtras());
-    transaction.replace(R.id.fragment_container, fragment, "fragment");
-    transaction.commit();
+  @Override
+  protected int getContentLayoutResId()
+  {
+    return R.layout.activity_fragment_and_toolbar;
+  }
+
+  @Override
+  protected String getFragmentClassName()
+  {
+    return BookmarkCategoriesFragment.class.getName();
+  }
+
+  @Override
+  protected int getFragmentContentResId()
+  {
+    return R.id.fragment_container;
   }
 }

android/src/com/mapswithme/maps/bookmarks/BookmarkListActivity.java

@@ -1,8 +1,6 @@
 package com.mapswithme.maps.bookmarks;
 
 import android.os.Bundle;
-import android.support.v4.app.Fragment;
-import android.support.v4.app.FragmentTransaction;
 import android.support.v7.widget.Toolbar;
 
 import com.mapswithme.maps.R;
@@ -16,15 +14,21 @@ public class BookmarkListActivity extends BaseMwmFragmentActivity
   {
     super.onCreate(savedInstanceState);
 
-    setContentView(R.layout.activity_fragment_and_toolbar);
     final Toolbar toolbar = getToolbar();
     toolbar.setTitle(R.string.bookmarks);
     UiUtils.showHomeUpButton(toolbar);
     displayToolbarAsActionBar();
+  }
 
-    FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
-    Fragment fragment = Fragment.instantiate(this, BookmarksListFragment.class.getName(), getIntent().getExtras());
-    transaction.replace(R.id.fragment_container, fragment, "fragment");
-    transaction.commit();
+  @Override
+  protected int getContentLayoutResId()
+  {
+    return R.layout.activity_fragment_and_toolbar;
+  }
+
+  @Override
+  protected int getFragmentContentResId()
+  {
+    return R.id.fragment_container;
   }
 }

android/src/com/mapswithme/maps/bookmarks/ChooseBookmarkCategoryActivity.java

@@ -2,9 +2,6 @@ package com.mapswithme.maps.bookmarks;
 
 import android.app.Activity;
 import android.content.Intent;
-import android.os.Bundle;
-import android.support.v4.app.Fragment;
-import android.support.v4.app.FragmentTransaction;
 
 import com.mapswithme.maps.base.BaseMwmFragmentActivity;
 
@@ -16,14 +13,9 @@ public class ChooseBookmarkCategoryActivity extends BaseMwmFragmentActivity
   public static final int REQUEST_CODE_EDIT_BOOKMARK = 0x2;
 
   @Override
-  protected void onCreate(Bundle savedInstanceState)
+  protected String getFragmentClassName()
   {
-    super.onCreate(savedInstanceState);
-
-    FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
-    Fragment fragment = Fragment.instantiate(this, ChooseBookmarkCategoryFragment.class.getName(), getIntent().getExtras());
-    transaction.replace(android.R.id.content, fragment, "fragment");
-    transaction.commit();
+    return ChooseBookmarkCategoryFragment.class.getName();
   }
 
   @Override

android/src/com/mapswithme/maps/search/SearchActivity.java

@@ -2,9 +2,6 @@ package com.mapswithme.maps.search;
 
 import android.content.Context;
 import android.content.Intent;
-import android.os.Bundle;
-import android.support.v4.app.Fragment;
-import android.support.v4.app.FragmentTransaction;
 
 import com.mapswithme.maps.base.BaseMwmFragmentActivity;
 
@@ -13,14 +10,9 @@ public class SearchActivity extends BaseMwmFragmentActivity
   public static final String EXTRA_QUERY = "search_query";
 
   @Override
-  protected void onCreate(Bundle savedInstanceState)
+  protected String getFragmentClassName()
   {
-    super.onCreate(savedInstanceState);
-
-    FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
-    Fragment fragment = Fragment.instantiate(this, SearchFragment.class.getName(), getIntent().getExtras());
-    transaction.replace(android.R.id.content, fragment, "fragment");
-    transaction.commit();
+    return SearchFragment.class.getName();
   }
 
   public static void startForSearch(Context context, String query)

android/src/com/mapswithme/maps/settings/StoragePathActivity.java

@@ -1,21 +1,12 @@
 package com.mapswithme.maps.settings;
 
-import android.os.Bundle;
-import android.support.v4.app.Fragment;
-import android.support.v4.app.FragmentTransaction;
-
 import com.mapswithme.maps.base.BaseMwmFragmentActivity;
 
 public class StoragePathActivity extends BaseMwmFragmentActivity
 {
   @Override
-  protected void onCreate(Bundle savedInstanceState)
+  protected String getFragmentClassName()
   {
-    super.onCreate(savedInstanceState);
-
-    FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
-    Fragment fragment = Fragment.instantiate(this, StoragePathFragment.class.getName(), getIntent().getExtras());
-    transaction.replace(android.R.id.content, fragment, "fragment");
-    transaction.commit();
+    return StoragePathFragment.class.getName();
   }
 }