Two-Way databinding in EditText

Question

I have this object

ObservableInt someNumber;

public ObservableInt getSomeNumber()
{
    return someNumber;
}

public void setSomeNumber(ObservableInt numbe         


        

Answer 1

There is an unpublished trick for simple primitive conversions:

<android.support.v7.widget.AppCompatEditText
    android:layout_width="0dp"
    android:layout_height="@dimen/agro_item_height"
    android:layout_weight="1"
    android:inputType="numberDecimal"
    android:text="@={`` + myObject.someNumber}"
    android:gravity="center_horizontal"/>

I believe it was only added in Android Studio 2.2.

Answer 2

Simply do this:

android:text="@={user.username}"

Full code:

 <EditText
            android:id="@+id/username"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:hint="user name"
            android:text="@={user.username}"/>

And User class

public class User {
public ObservableField<String> username = new ObservableField<>();
public ObservableField<String> password = new ObservableField<>();

public User() {
    this("", "");
}

public User(String username, String password) {
    this.username.set(username);
    this.password.set(password);
}

Answer 3

Thanks to the binding adapters from @LongRanger I was able to advance a lot more in my solution but I had to make some changes on the adapters and in my code. First of all I had to init the ObservableInt member like this:

ObservableInt someNumber;

public ObservableInt getSomeNumber()
{
    return someNumber;
}

public void setSomeNumber(ObservableInt number)
{
    this.someNumber = number;
}

Second, I had to change the adapters given by @LongRanger to be like this:

@BindingAdapter("android:text")
public static void bindIntegerInText(AppCompatEditText tv, int value)
{
    tv.setText(String.valueOf(value));    

    // Set the cursor to the end of the text
    tv.setSelection(tv.getText().length());
}

@InverseBindingAdapter(attribute = "android:text")
public static int getIntegerFromBinding(TextView view)
{
    String string = view.getText().toString();

    return string.isEmpty() ? 0 : Integer.parseInt(string);
}

That way I avoid the error: Invalid int "", when trying to do Integer.parse(...) on the @InverseBindingAdapter. After this I had to put the cursor on the end of the EditText with the @BindingAdapter, otherwise the cursor kept moving to the start.

Answer 4

You can do two-way binding on EditText.

Using one-way data binding, you can set a value on an attribute and set a listener that reacts to a change in that attribute

variable is string type

<android.support.v7.widget.AppCompatEditText
    ...
    android:text="@={model.someString}"
    />

variable is number

<android.support.v7.widget.AppCompatEditText
    ...
    android:text="@={`` + model.someNumber}"
    />

`` two back apostrophe do binding automatically

• convert number to string when setting it on EditText
• convert string text to number when setting in Model

Tip

From documentation you can see, two-way binding can be used for many purpose.

1. CheckBox, RadioButton, Switch, ToggleButton

android:checked="@={model.checked}"

2. RadioGroup - android:checkedButton

android:checkedButton="@={model.selectedId}"

3. RatingBar - android:rating

android:rating="@={model.rating}"

etc.

Answer 5

I try to use the custom setter as @George Mount mentioned(https://medium.com/google-developers/android-data-binding-custom-setters-55a25a7aea47#.vsry4d95w) , and inspired by this answer (Android two way binding with Integer type causes databinding does not exist)

You can still use the original code for two-way binding.

Model class

public class Age {
    private ObservableInt someNumber;
    private ObservableField<String> someStr;
    public Age() {
        someNumber = new ObservableInt();
        someStr = new ObservableField<>();
    }
    public ObservableInt getSomeNumber() {
        return someNumber;
    }
    public void setSomeNumber(ObservableInt pSomeNumber) {
        someNumber.set(pSomeNumber.get());
    }
    public ObservableField<String> getSomeStr() {
        return someStr;
    }
    public void setSomeStr(ObservableField<String> pSomeStr) {
        someStr.set(pSomeStr.get());
    }
}

Custom setter and getter for the attribute

@BindingAdapter("android:text")
public static void bindIntegerInText(AppCompatEditText tv, int value) {
    tv.setText(String.valueOf(value));
}
@InverseBindingAdapter(attribute = "android:text")
public static int getIntegerFromBinding(TextView view) {
    return Integer.parseInt(view.getText().toString());
}

Code in Activity

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    ActivityMain2Binding binding = DataBindingUtil.setContentView(this, R.layout.activity_main2);
    mAge = new Age();
    mAge.setSomeNumber(new ObservableInt(3));
    mAge.setSomeStr(new ObservableField<>("Test"));
    binding.setAge(mAge);
    binding.btn.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            mAge.setSomeNumber(new ObservableInt(4));
            mAge.setSomeStr(new ObservableField<>("Hello World"));
        }
    });
}

I make 4 demo with ObservableInt, Observable , normal String resource and binding String resource in the xml.

<string name="helloworld">Hello World</string>

activity_main3.xml

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

    >

    <data>

        <variable
            name="age"
            type="example.com.testerapplication.Age"/>
    </data>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical">

        <android.support.v7.widget.AppCompatEditText
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="@={age.someNumber}"/>

        <android.support.v7.widget.AppCompatEditText
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="@={age.someStr}"/>

        <android.support.v7.widget.AppCompatEditText
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="@string/helloworld"/>

        <android.support.v7.widget.AppCompatEditText
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="@{@string/helloworld}"/>

        <Button
            android:id="@+id/btn"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="Test"
            />
    </LinearLayout>

</layout>

Answer 6

@CommonsWare is right, you should use ObservableField<Str‌​ing> instead of ObservableInt. If you really needit as number, just parse it Integer.valueOf(stringNumber).

public ObservableField<Str‌​ing> someNumber;

//and in xml code:

<EditText
        android:layout_width="0dp"
        android:layout_height="@dimen/agro_item_height"
        android:layout_weight="1"
        android:inputType="numberDecimal"
        android:text="@={myObject.someNumber}"
        android:gravity="center_horizontal"/>

EDITED: Or, as mentioned, write custom @InverseBindingAdapter

public class MyEditTextBindingAdapters {

    @BindingConversion
    public static String intToStr(Integer value) {
        return value != null ? String.valueOf(value) : "";
    }

    @InverseBindingAdapter(attribute = "android:text")
    public static Integer captureIntValue(EditText view) {
        long value = 0;
        try {
            value = Integer.parseInt(view.getText().toString());
        } catch (NumberFormatException e) {
            e.printStackTrace();
        }
        return value;
    }
}