Android Data Binding @BindingConversion failure for int to string

Question

Ran into a mysterious problem when trying to make a @BindingConversion for int to string.
The following code works for floats to strings:

xml:

...
<variable
        name="myViewModel"
        type="... .SomeModel" />
...
<TextView
            style="@style/StyleStuff"
            android:text="@{myViewModel.number}" />

code:

public class SomeModel {
    public ObservableFloat number = new ObservableFloat();
}

and setting:

viewModel.number.set(3.14f);

But if I try the same thing for ints to strings I get a crash.

 public ObservableInt number = new ObservableInt();

with

viewModel.number.set(42);

I get the following:

FATAL EXCEPTION: main
Process: ...myapplication, PID: 14311
android.content.res.Resources$NotFoundException: String resource ID #0xfa0
    at android.content.res.Resources.getText(Resources.java:1123)
    at android.support.v7.widget.ResourcesWrapper.getText(ResourcesWrapper.java:52)
    at android.widget.TextView.setText(TextView.java:4816)
    at ...executeBindings(ActivityAdaptersBinding.java:336)
    at android.databinding.ViewDataBinding.executePendingBindings(ViewDataBinding.java:355)

Any ideas? Thanks!

CommonsWare · Accepted Answer · 2019-07-20T19:51:17.660

238

android:text with an int assumes that the int is a string resource ID. Use android:text="@{Integer.toString(myViewModel.number)}".

~~You will also need to import the Integer class:~~ (no longer needed)

edited Jul 20 '19 at 19:51

answered Jun 16 '16 at 19:42

CommonsWare

986,068
189
2,389
2,491

1

Aha! Thank you! I would've thought data binding would check and convert the int before it hit the text view, but apparently not~ This means that we should be careful whenever using BindingConversion if the original type might be misinterpreted and used without hitting the converter. – Dave Jun 17 '16 at 01:20
@Dave: "I would've thought data binding would check and convert the int before it hit the text view" -- no, because for all data binding knows, you *are* giving it a string resource ID. "This means that we should be careful" -- yes. :-) – CommonsWare Jun 17 '16 at 11:34
5

How would you do this if you wanted to create 2-way binding? – InfernalRapture Aug 08 '16 at 02:17
1

@InfernalRapture: Perhaps an `@InverseBindingAdapter`, though I haven't played with that yet. – CommonsWare Aug 08 '16 at 10:56
@CommonsWare That was what I was looking for, after a few hours of messing around that was the trick of it. – InfernalRapture Aug 08 '16 at 17:48
It matters that the import is before anything else, like in my case were i had a variable in my data clause. Import types must be before the variable. – ZooMagic Aug 02 '18 at 15:10
I dont think import is necessary. As java.lang.* are available by default – Irshad Kumail Jul 20 '19 at 19:50
how its possible two way bindings? – Sreejesh K Nair Mar 25 '20 at 06:00
@SreejeshKNair: `TextView` does not support input, so there is no need for a two-way binding with `TextView`. – CommonsWare Mar 25 '20 at 11:46

Wesely · Answer 2 · 2019-07-04T07:20:02.977

28

Beware, In latest DataBinding (2019), It does NOT require importing Integer nor String or you will get this error:

****/ data binding error ****msg:Missing import expression although it is registered file

official doc says : java.lang.* is imported automatically.

Just go either

android:text="@{Integer.toString(myViewModel.number)}" or

android:text="@{String.valueOf(myViewModel.number)}"

directly.

edited Jul 04 '19 at 07:20

answered Apr 24 '19 at 03:39

Wesely

1,425
14
23

This is should be upvoted, today databinding doesn't need to import `java.lang.String` or `java.lang.Integer` in order to do the conversion. – Rhony May 25 '19 at 07:34

score 23 · Answer 3 · edited Jul 14 '18 at 03:06

23

Convert int to string for set in TextView like below:

android:text="@{String.valueOf(myViewModel.number)}"

Also, String class must be imported by the layout:

<layout>
   <data>
      <import type="java.lang.String" />
   </data>

   …

</layout>

edited Jul 14 '18 at 03:06

Raja Jawahar

6,742
9
45
56

answered Oct 06 '17 at 12:54

Marjan Davodinejad

449
5
11

score 19 · Answer 4 · edited Jun 20 '20 at 09:12

19

Simplest solution, may be it would help someone.

android:text="@{`` + model.intValue}"

This can be used in two-way binding for EditText also. Where users input is set as Integer value in model, and shown as String.

android:text="@={`` + model.intValue}"

See this answer also.

edited Jun 20 '20 at 09:12

Community

1
1

answered Aug 01 '18 at 19:00

Khemraj Sharma

57,232
27
203
212

score 6 · Answer 5 · answered Dec 25 '18 at 08:30

6

This worked for me

  <TextView
        android:id="@+id/number"
        android:text='@={Converter.convertIntToString(myViewModel.number)}'

        />

Converter class with inverse method

public class Converter {


public static int convertStringToInt(String text) {
   return Integer.parseInt(text);
}

@InverseMethod(value="convertStringToInt")
public static String convertIntToString(int value) {
    return Integer.toString(value);
}}

answered Dec 25 '18 at 08:30

shahana kareen

364
4
10

4

This is overkill! – OhhhThatVarun Sep 24 '19 at 09:15
1

You can use Binding Adapter for this. – felipe.rce Jan 20 '20 at 02:12

score 6 · Answer 6 · answered Mar 15 '21 at 05:44

6

It's too late but i update it for newbies. You can parse to int in xml by using:

Integer.parseInt(string)

or to String by:

String.valueOf(string)

answered Mar 15 '21 at 05:44

Hosein Haqiqian

579
9
16

Android Data Binding @BindingConversion failure for int to string

6 Answers6

Simplest solution, may be it would help someone.

Linked

Related