An Android Jetpack Data Binding Tutorial - Revision history

Neil: /* Adding Binding Expressions */

2019-01-16T18:43:43Z

‎Adding Binding Expressions

2019-01-16T18:43:26Z

‎Working with the Binding Class

2019-01-16T18:43:05Z

‎Adding the Layout Element

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 With these changes made, the next step is to begin inserting some binding expressions into the view elements of the data binding layout file.
 == Adding Binding Expressions ==
 The first binding expression will bind the resultText TextView to the result value within the model view. Edit the main_fragment.xml file, locate the resultText element and modify the text property so that the element reads as follows:
@@ Line 239: / Line 239: @@
     android:layout_width="wrap_content"
     android:layout_height="wrap_content"
     android:text='@{safeUnbox(myViewModel.result) == 0.0 ? "Enter value" : String.valueOf(safeUnbox(myViewModel.result)) + " euros"}'
     app:layout_constraintBottom_toBottomOf="parent"

@@ Line 155: / Line 155: @@
 Build and run the app once again to make sure that these changes take effect.
 == Working with the Binding Class ==
 The next step is to modify the code within the MainFragment.java file to obtain a reference to the binding class instance. This is best achieved by rewriting the onCreateView() method:
@@ Line 184: / Line 184: @@
         return binding.getRoot();
+    }
+.

@@ Line 96: / Line 96: @@
 == Adding the Layout Element ==
 As described in “An Overview of Android Jetpack Data Binding”, in order to be able to use data binding, the layout hierarchy must have a layout component as the root view. This requires that the following changes be made to the main_fragment.xml layout file (app -> res -> layout -> main_fragment.xml). Open this file in the layout editor tool, switch to Text mode and make these changes:
@@ Line 108: / Line 108: @@
         <android.support.constraint.ConstraintLayout
             android:id="@+id/main"
             android:layout_width="match_parent"