Change unique ID generation to UUID

Author: Daniel Novak

library/src/main/java/eu/inloop/viewmodel/AbstractViewModel.java

@@ -11,12 +11,12 @@
 
 public abstract class AbstractViewModel<T extends IView> {
 
-    private int mUniqueIdentifier;
+    private String mUniqueIdentifier;
 
     @Nullable
     private T mView;
 
-    void setUniqueIdentifier(int uniqueIdentifier) {
+    void setUniqueIdentifier(String uniqueIdentifier) {
         mUniqueIdentifier = uniqueIdentifier;
     }
 
@@ -25,7 +25,7 @@ void setUniqueIdentifier(int uniqueIdentifier) {
      * @return An app unique identifier for the current viewmodel instance (will be kept during orientation
      * change). This identifier will be reset in case the corresponding activity is killed.
      */
-    public int getUniqueIdentifier() {
+    public String getUniqueIdentifier() {
         return mUniqueIdentifier;
     }
 

library/src/main/java/eu/inloop/viewmodel/ViewModelHelper.java

@@ -8,15 +8,15 @@
 import android.support.v4.app.Fragment;
 import android.util.Log;
 
+import java.util.UUID;
 import java.util.concurrent.atomic.AtomicInteger;
 
 public class ViewModelHelper<T extends IView, R extends AbstractViewModel<T>> {
 
-    private int mScreenId;
+    private String mScreenId;
     private R mViewModel;
     private boolean mModelRemoved;
     private boolean mOnSaveInstanceCalled;
-    private static final AtomicInteger sModelIndex = new AtomicInteger(0);
 
     /**
      * Call from {@link android.app.Activity#onCreate(android.os.Bundle)} or
@@ -38,9 +38,9 @@ public void onCreate(@Nullable Bundle savedInstanceState,
 
         // screen (activity/fragment) created for first time, attach unique ID
         if (savedInstanceState == null) {
-            mScreenId = sModelIndex.incrementAndGet();
+            mScreenId = UUID.randomUUID().toString();
         } else {
-            mScreenId = savedInstanceState.getInt("identifier");
+            mScreenId = savedInstanceState.getString("identifier");
             mOnSaveInstanceCalled = false;
         }
 
@@ -161,7 +161,7 @@ public R getViewModel() {
      * @param bundle
      */
     public void onSaveInstanceState(@NonNull Bundle bundle) {
-        bundle.putInt("identifier", mScreenId);
+        bundle.putString("identifier", mScreenId);
         if (mViewModel != null) {
             mViewModel.saveState(bundle);
             mOnSaveInstanceCalled = true;

library/src/main/java/eu/inloop/viewmodel/ViewModelProvider.java

@@ -2,6 +2,8 @@
 import android.support.annotation.NonNull;
 import android.util.SparseArray;
 
+import java.util.HashMap;
+
 /**
  * Create and keep this class inside your Activity. Store it
  * in {@link android.support.v4.app.FragmentActivity#onRetainCustomNonConfigurationInstance()
@@ -12,32 +14,32 @@ public class ViewModelProvider {
 
     private static final ViewModelProvider sInstance = new ViewModelProvider();
 
-    private final SparseArray<AbstractViewModel<? extends IView>> mViewModelCache;
+    private final HashMap<String, AbstractViewModel<? extends IView>> mViewModelCache;
 
     private ViewModelProvider() {
-        mViewModelCache = new SparseArray<>();
+        mViewModelCache = new HashMap<>();
     }
 
     public static ViewModelProvider getInstance() {
         return sInstance;
     }
 
-    public synchronized void remove(int modelIndex) {
-        mViewModelCache.remove(modelIndex);
+    public synchronized void remove(String modeIdentifier) {
+        mViewModelCache.remove(modeIdentifier);
     }
 
     @SuppressWarnings("unchecked")
     @NonNull
-    public synchronized <T extends IView> ViewModelWrapper<T> getViewModel(int modelIndex, @NonNull Class<? extends AbstractViewModel<T>> viewModelClass) {
-        AbstractViewModel<T> instance = (AbstractViewModel<T>) mViewModelCache.get(modelIndex);
+    public synchronized <T extends IView> ViewModelWrapper<T> getViewModel(String modelIdentifier, @NonNull Class<? extends AbstractViewModel<T>> viewModelClass) {
+        AbstractViewModel<T> instance = (AbstractViewModel<T>) mViewModelCache.get(modelIdentifier);
         if (instance != null) {
             return new ViewModelWrapper<>(instance, false);
         }
 
         try {
             instance = viewModelClass.newInstance();
-            instance.setUniqueIdentifier(modelIndex);
-            mViewModelCache.put(modelIndex, instance);
+            instance.setUniqueIdentifier(modelIdentifier);
+            mViewModelCache.put(modelIdentifier, instance);
             return new ViewModelWrapper<>(instance, true);
         } catch (Exception ex) {
             throw new RuntimeException(ex);