Data binding: How pass Context in xml to method?

Question

Android Studio 3.0.

Here my custom method:

public static int getTileWidthDpInScreen(Context context) {
    // some code here
    return tileWidthDp;
}

here my xml file with data binding code :

<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools">

    <data>

        <import type="com.myproject.android.customer.util.GUIUtil" />

    </data>

    <android.support.constraint.ConstraintLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

        <ImageView
            android:id="@+id/imageViewPhoto"
            android:layout_width="@{GUIUtil.getTileWidthDpInScreen()}"
            android:layout_height="@dimen/preview_image_height"
            android:scaleType="centerCrop"
            app:layout_constraintLeft_toLeftOf="parent"
            app:layout_constraintRight_toRightOf="parent"
            app:layout_constraintTop_toTopOf="parent" />       


    </android.support.constraint.ConstraintLayout>

</layout>

And as result I get error:

e: java.lang.IllegalStateException: failed to analyze: android.databinding.tool.util.LoggedErrorException: Found data binding errors.
data binding error msg:cannot find method getTileWidthDpInScreen() in class com.myproject.android.customer.util.GUIUtil

This error because I'm not pass context in method getTileWidthDpInScreen().

How I get context in xml and pass it in method: getTileWidthDpInScreen()?

OK. It's work: A special variable named context is generated for use in binding expressions as needed. The value for context is the Context from the root View's getContext(). The context variable will be overridden by an explicit variable declaration with that name. So as result here work code: android:layout_width="@{GUIUtil.getTileWidthDpInScreen(context)}" — Alex
– Alex, Commented Nov 29, 2017 at 9:08
Possible duplicate of Android DataBinding where to get context? — dalla92
– dalla92, Commented Nov 29, 2017 at 9:13

Jéwôm' · Accepted Answer · 2019-08-28 11:08:51Z

20

The Android documentation say :

A special variable named context is generated for use in binding expressions as needed. The value for context is the Context object from the root View's getContext() method. The context variable is overridden by an explicit variable declaration with that name.

So the solution is : android:layout_width="@{GUIUtil.getTileWidthDpInScreen(context)}

answered Aug 28, 2019 at 11:08

Jéwôm'

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Morgan Koh · Accepted Answer · 2019-10-16 06:51:44Z

6

You just have to import <import type="android.content.Context" /> in your xml data imports.

Then, you can access context for your databinding simply with context.

<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android">

    <data>
        <import type="android.content.Context" />

        <import type="com.myproject.android.customer.util.GUIUtil" />
    </data>

    <androidx.constraintlayout.widget.ConstraintLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

        <ImageView
            android:id="@+id/imageViewPhoto"
            android:layout_width="@{GUIUtil.getTileWidthDpInScreen(context)}"
            android:layout_height="@dimen/preview_image_height"
            android:scaleType="centerCrop"
            app:layout_constraintLeft_toLeftOf="parent"
            app:layout_constraintRight_toRightOf="parent"
            app:layout_constraintTop_toTopOf="parent" />

    </androidx.constraintlayout.widget.ConstraintLayout>
</layout>

answered Oct 16, 2019 at 6:51

Morgan Koh

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1 Comment

João Miranda Over a year ago

It is not necessary to import Context, data binding already adds the variable context to the scope

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