Data binding: set property if it isn't null

user_3253896 0
Viewed 61221

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.

android-databinding android
3 Answers

Data binding does not need to check for null value, it will be handled by binding class.

If you need to check null for other purpose (like setting default value) then you can use like this.

android:text='@{item.gender != null ? item.gender : @string/male}'

or 

android:text='@{item.gender ?? @string/male}'

Both above examples are same. Here @string/male is default value, when item.gender is null.

user_68915630

I tried something like this.

<layout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto">

  <data>
     <import type="android.text.TextUtils"/>
     <variable
        name="mOrder"
        type="com.test.app.models.Order" />
  </data>
  <TextView
    android:id="@+id/mLblSource"
    android:layout_width="100dp"
    android:layout_height="40dp"
    android:layout_marginTop="8dp"
    android:layout_marginEnd="8dp"
    android:text='@{TextUtils.isEmpty(mOrder.order_id) ? "- -" : mOrder.order_id}'
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintBottom_toBottomOf="parent" />
</layout>
user_40657690
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