Improved implementation

Author: johnkil

.travis.yml

@@ -4,8 +4,8 @@ android:
   components:
     - platform-tools
     - tools
-    - android-23
-    - build-tools-23.0.3
+    - android-24
+    - build-tools-24.0.0
     - extra-android-m2repository
     - extra-android-support
 

CHANGELOG.md

@@ -2,6 +2,13 @@ Change Log
 ==========
 
 
+## Version 1.1.0
+
+_2016-07-07_
+
+Improved implementation.
+
+
 ## Version 1.0.0
 
 _2016-05-26_

README.md

@@ -15,7 +15,7 @@ Implementation of the multiple back stacks. Using this library allows implementa
 Compatibility
 -------------
 
-This library is compatible from API 7 (Android 2.1).
+This library is compatible from API 9 (Android 2.3).
 
 
 Download
@@ -36,7 +36,7 @@ Add the dependency
 
 ```groovy
 dependencies {
-    compile 'com.github.jetradarmobile:multibackstack:1.0.0'
+    compile 'com.github.jetradarmobile:multibackstack:1.1.0'
 }
 ```
 

multibackstack-sample/src/main/java/com/jetradar/multibackstack/sample/MainActivity.java

@@ -30,54 +30,67 @@
 import static com.ashokvarma.bottomnavigation.BottomNavigationBar.OnTabSelectedListener;
 
 public class MainActivity extends BackStackActivity implements OnTabSelectedListener {
-  private static final String STATE_TAB_ID = "tab_id";
+  private static final String STATE_CURRENT_TAB_ID = "current_tab_id";
   private static final int MAIN_TAB_ID = 0;
 
-  private BottomNavigationBar bottomNavigationBar;
+  private BottomNavigationBar bottomNavBar;
   private Fragment curFragment;
   private int curTabId;
 
   @Override
   protected void onCreate(Bundle state) {
     super.onCreate(state);
     setContentView(R.layout.activity_main);
-    setUpBottomNavigationBar();
+    setUpBottomNavBar();
+
+    if (state == null) {
+      bottomNavBar.selectTab(MAIN_TAB_ID, false);
+      showFragment(rootTabFragment(MAIN_TAB_ID));
+    }
   }
 
-  private void setUpBottomNavigationBar() {
-    bottomNavigationBar = (BottomNavigationBar) findViewById(R.id.bottom_navigation);
-    bottomNavigationBar
+  private void setUpBottomNavBar() {
+    bottomNavBar = (BottomNavigationBar) findViewById(R.id.bottom_navigation);
+    bottomNavBar
         .addItem(new BottomNavigationItem(R.drawable.ic_search_24dp, R.string.search))
-        .addItem(new BottomNavigationItem(R.drawable.ic_favorite_24dp, R.string.favorite))
+        .addItem(new BottomNavigationItem(R.drawable.ic_favorite_24dp, R.string.favorites))
         .addItem(new BottomNavigationItem(R.drawable.ic_profile_24dp, R.string.profile))
         .initialise();
+    bottomNavBar.setTabSelectedListener(this);
+  }
 
-    bottomNavigationBar.setTabSelectedListener(this);
-    if (getSupportFragmentManager().findFragmentById(R.id.content) == null) {
-      bottomNavigationBar.selectTab(MAIN_TAB_ID, false);
-      showFragment(fragmentByTab(MAIN_TAB_ID));
+  @NonNull
+  private Fragment rootTabFragment(int tabId) {
+    switch (tabId) {
+      case 0:
+        return ItemListFragment.newInstance(getString(R.string.search));
+      case 1:
+        return ItemListFragment.newInstance(getString(R.string.favorites));
+      case 2:
+        return ItemListFragment.newInstance(getString(R.string.profile));
+      default:
+        throw new IllegalArgumentException();
     }
   }
 
   @Override
   protected void onRestoreInstanceState(Bundle savedInstanceState) {
     super.onRestoreInstanceState(savedInstanceState);
     curFragment = getSupportFragmentManager().findFragmentById(R.id.content);
-    curTabId = savedInstanceState.getInt(STATE_TAB_ID);
-    bottomNavigationBar.selectTab(curTabId, false);
+    curTabId = savedInstanceState.getInt(STATE_CURRENT_TAB_ID);
+    bottomNavBar.selectTab(curTabId, false);
   }
 
   @Override
   protected void onSaveInstanceState(Bundle outState) {
-    outState.putInt(STATE_TAB_ID, curTabId);
+    outState.putInt(STATE_CURRENT_TAB_ID, curTabId);
     super.onSaveInstanceState(outState);
   }
 
-  @SuppressWarnings("ConstantConditions")
   @Override
   public void onBackPressed() {
-    if (!backStackManager.empty()) {
-      Pair<Integer, Fragment> pair = popFromBackStack();
+    Pair<Integer, Fragment> pair = popFragmentFromBackStack();
+    if (pair != null) {
       backTo(pair.first, pair.second);
     } else {
       super.onBackPressed();
@@ -87,14 +100,14 @@ public void onBackPressed() {
   @Override
   public void onTabSelected(int position) {
     if (curFragment != null) {
-      pushToBackStack(curTabId, curFragment);
+      pushFragmentToBackStack(curTabId, curFragment);
     }
     curTabId = position;
-    curFragment = popFromBackStack(curTabId);
-    if (curFragment == null) {
-      curFragment = fragmentByTab(curTabId);
+    Fragment fragment = popFragmentFromBackStack(curTabId);
+    if (fragment == null) {
+      fragment = rootTabFragment(curTabId);
     }
-    replaceFragment(curFragment);
+    replaceFragment(fragment);
   }
 
   @Override
@@ -105,55 +118,45 @@ public void onTabReselected(int position) {
   @Override
   public void onTabUnselected(int position) {}
 
-  private Fragment fragmentByTab(int tabId) {
-    switch (tabId) {
-      case 0:
-        return ItemListFragment.newInstance(getString(R.string.search));
-      case 1:
-        return ItemListFragment.newInstance(getString(R.string.favorite));
-      case 2:
-        return ItemListFragment.newInstance(getString(R.string.profile));
-      default:
-        throw new IllegalArgumentException();
-    }
-  }
-
   public void showFragment(@NonNull Fragment fragment) {
     showFragment(fragment, true);
   }
 
   public void showFragment(@NonNull Fragment fragment, boolean addToBackStack) {
     if (curFragment != null && addToBackStack) {
-      pushToBackStack(curTabId, curFragment);
+      pushFragmentToBackStack(curTabId, curFragment);
     }
-    curFragment = fragment;
     replaceFragment(fragment);
   }
 
   private void backTo(int tabId, @NonNull Fragment fragment) {
-    curTabId = tabId;
-    bottomNavigationBar.selectTab(curTabId, false);
-    curFragment = fragment;
+    if (tabId != curTabId) {
+      curTabId = tabId;
+      bottomNavBar.selectTab(curTabId, false);
+    }
     replaceFragment(fragment);
     getSupportFragmentManager().executePendingTransactions();
   }
 
   private void backToRoot() {
-    Fragment originalRootFragment = fragmentByTab(curTabId);
-    if (curFragment.getClass() != originalRootFragment.getClass()) {
-      Fragment rootFragment = popRootFromBackStack(curTabId);
-      if (rootFragment == null || rootFragment.getClass() != originalRootFragment.getClass()) {
-        rootFragment = originalRootFragment;
-      }
-      curFragment = rootFragment;
-      replaceFragment(rootFragment);
+    if (isRootTabFragment(curFragment, curTabId)) {
+      return;
     }
+    resetBackStackToRoot(curTabId);
+    Fragment rootFragment = popFragmentFromBackStack(curTabId);
+    assert rootFragment != null;
+    backTo(curTabId, rootFragment);
+  }
+
+  private boolean isRootTabFragment(@NonNull Fragment fragment, int tabId) {
+    return fragment.getClass() == rootTabFragment(tabId).getClass();
   }
 
   private void replaceFragment(@NonNull Fragment fragment) {
     FragmentManager fm = getSupportFragmentManager();
     FragmentTransaction tr = fm.beginTransaction();
     tr.replace(R.id.content, fragment);
-    tr.commit();
+    tr.commitAllowingStateLoss();
+    curFragment = fragment;
   }
 }

multibackstack-sample/src/main/res/values/strings.xml

@@ -2,6 +2,6 @@
   <string name="app_name">MultiBackStack</string>
 
   <string name="search">Search</string>
-  <string name="favorite">Favorite</string>
+  <string name="favorites">Favorites</string>
   <string name="profile">Profile</string>
 </resources>

multibackstack/build.gradle

@@ -5,7 +5,7 @@ android {
   buildToolsVersion rootProject.ext.buildToolsVersion
 
   defaultConfig {
-    minSdkVersion 7
+    minSdkVersion 9
   }
 }
 

multibackstack/src/main/java/com/jetradar/multibackstack/BackStack.java

@@ -25,24 +25,23 @@
 
 public class BackStack implements Parcelable {
   public final int hostId;
-  private final Stack<BackStackEntry> stack;
+  private final Stack<BackStackEntry> entriesStack = new Stack<>();
 
   public BackStack(int hostId) {
     this.hostId = hostId;
-    stack = new Stack<>();
   }
 
   public void push(@NonNull BackStackEntry entry) {
-    stack.push(entry);
+    entriesStack.push(entry);
   }
 
   @Nullable
   public BackStackEntry pop() {
-    return empty() ? null : stack.pop();
+    return empty() ? null : entriesStack.pop();
   }
 
   public boolean empty() {
-    return stack.empty();
+    return entriesStack.empty();
   }
 
   @Override
@@ -53,19 +52,18 @@ public int describeContents() {
   @Override
   public void writeToParcel(Parcel out, int flags) {
     out.writeInt(hostId);
-    int len = stack.size();
-    out.writeInt(len);
-    for (int i = 0; i < len; i++) {
-      stack.get(i).writeToParcel(out, flags);
+    int size = entriesStack.size();
+    out.writeInt(size);
+    for (int i = 0; i < size; i++) {
+      entriesStack.get(i).writeToParcel(out, flags);
     }
   }
 
   private BackStack(Parcel in) {
     hostId = in.readInt();
-    int len = in.readInt();
-    stack = new Stack<>();
-    for (int i = 0; i < len; i++) {
-      stack.push(BackStackEntry.CREATOR.createFromParcel(in));
+    int size = in.readInt();
+    for (int i = 0; i < size; i++) {
+      entriesStack.push(BackStackEntry.CREATOR.createFromParcel(in));
     }
   }
 

multibackstack/src/main/java/com/jetradar/multibackstack/BackStackActivity.java

@@ -25,7 +25,7 @@
 import android.util.Log;
 
 public abstract class BackStackActivity extends AppCompatActivity {
-  private static final String STATE_BACK_STACK = "back_stack";
+  private static final String STATE_BACK_STACK_MANAGER = "back_stack_manager";
 
   protected BackStackManager backStackManager;
 
@@ -44,16 +44,16 @@ protected void onDestroy() {
   @Override
   protected void onSaveInstanceState(Bundle outState) {
     super.onSaveInstanceState(outState);
-    outState.putParcelable(STATE_BACK_STACK, backStackManager.saveState());
+    outState.putParcelable(STATE_BACK_STACK_MANAGER, backStackManager.saveState());
   }
 
   @Override
   protected void onRestoreInstanceState(Bundle savedInstanceState) {
     super.onRestoreInstanceState(savedInstanceState);
-    backStackManager.restoreState(savedInstanceState.getParcelable(STATE_BACK_STACK));
+    backStackManager.restoreState(savedInstanceState.getParcelable(STATE_BACK_STACK_MANAGER));
   }
 
-  protected boolean pushToBackStack(int hostId, @NonNull Fragment fragment) {
+  protected boolean pushFragmentToBackStack(int hostId, @NonNull Fragment fragment) {
     try {
       BackStackEntry entry = BackStackEntry.create(getSupportFragmentManager(), fragment);
       backStackManager.push(hostId, entry);
@@ -65,20 +65,22 @@ protected boolean pushToBackStack(int hostId, @NonNull Fragment fragment) {
   }
 
   @Nullable
-  protected Fragment popFromBackStack(int hostId) {
+  protected Fragment popFragmentFromBackStack(int hostId) {
     BackStackEntry entry = backStackManager.pop(hostId);
     return entry != null ? entry.toFragment(this) : null;
   }
 
   @Nullable
-  protected Pair<Integer, Fragment> popFromBackStack() {
+  protected Pair<Integer, Fragment> popFragmentFromBackStack() {
     Pair<Integer, BackStackEntry> pair = backStackManager.pop();
     return pair != null ? Pair.create(pair.first, pair.second.toFragment(this)) : null;
   }
 
-  @Nullable
-  protected Fragment popRootFromBackStack(int hostId) {
-    BackStackEntry entry = backStackManager.popRoot(hostId);
-    return entry != null ? entry.toFragment(this) : null;
+  protected boolean resetBackStackToRoot(int hostId) {
+    return backStackManager.resetToRoot(hostId);
+  }
+
+  protected boolean clearBackStack(int hostId) {
+    return backStackManager.clear(hostId);
   }
 }

multibackstack/src/main/java/com/jetradar/multibackstack/BackStackEntry.java

@@ -27,9 +27,9 @@
 import android.support.v4.app.FragmentManager;
 
 public class BackStackEntry implements Parcelable {
-  private final String fname;
-  private final SavedState state;
-  private final Bundle args;
+  public final String fname;
+  public final SavedState state;
+  public final Bundle args;
 
   public BackStackEntry(@NonNull String fname, @Nullable SavedState state, @Nullable Bundle args) {
     this.fname = fname;