Data binding: set property if it isn't null

Question

Cannot understand... How to set some property of view only if variable field isn't null?
For example

<?xml version="1.0" encoding="utf-8"?> <layout xmlns:android="http://schemas.android.com/apk/res/android">      <data>         <variable             name="item"             type="com.test.app.Item" />     </data>      <RelativeLayout         android:layout_width="match_parent"         android:layout_height="60dp"         android:orientation="horizontal">          <ImageView             android:id="@+id/icon"             android:layout_width="wrap_content"             android:layout_height="wrap_content"             android:layout_alignParentLeft="true"             android:layout_alignParentStart="true"             android:layout_centerVertical="true"             android:layout_margin="16dp"             android:src="@{item.getDrawable()}"/>          <LinearLayout             android:layout_width="match_parent"             android:layout_height="wrap_content"             android:layout_centerVertical="true"             android:layout_marginEnd="16dp"             android:layout_marginLeft="72dp"             android:layout_marginRight="16dp"             android:layout_marginStart="72dp"             android:layout_toLeftOf="@id/action"             android:layout_toStartOf="@id/action"             android:orientation="vertical">              <TextView                 android:id="@+id/text1"                 android:layout_width="match_parent"                 android:layout_height="wrap_content"                 android:singleLine="true"                 android:textColor="@color/black_87"                 android:textSize="16sp"                 android:text="@{item.getTitle()}"/>              <TextView                 android:id="@+id/text2"                 android:layout_width="match_parent"                 android:layout_height="wrap_content"                 android:autoLink="web|email"                 android:linksClickable="false"                 android:singleLine="true"                 android:textColor="@color/black_54"                 android:textSize="14sp"                 android:text="@{item.getSubtitle()}"/>           </LinearLayout>      </RelativeLayout> </layout> 

Some field of Item can be null and I won't call methods of layout views unnecessarily. And I won't get NullPointerException. How can I set property only if it isn't null?
P.S. Sorry for English.

Answer 1

Well data binding avoids NullPointerException in general by checking for it and assigns the default value (null for example) even if item itself is null in your example.

But a basic example for null checks for the item's properties:

android:text='@{item.title != null ? user.title : ""}' 

Or use the "Null Coalescing Operator". The null coalescing operator (??) chooses the left operand if it is not null or the right if it is null.

android:text='@{item.title ?? ""}' 

Note that title or getTitle doesn't matter.