Android onfocuschange in xml

Question

I have an Android app, and in the xml layout file I have something like this:

    <CheckBox
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:id="@+id/checkBoxDone"
    android:checked="false"
    android:clickable="true"
    android:onClick="doneCheckBoxClicked" />

Then in the java code I implemented

    public void doneCheckBoxClicked(View v) { ...}

Can I use similar approach for focus changing actions. Have in the xml something like

android:onFocusChanged="editTextFieldFocusChanged"

and then in java code:

public void editTextFieldFocusChanged(View v, boolean hasFocus) { ...}

Or there is no way to do onFocusChange in the xml?

Answer 1

If you are using Android data binding to bind your handlers then you could write a custom BindingAdapter anywhere in your code to pass your handler from xml to java:

@BindingAdapter("app:onFocusChange")
public static void onFocusChange(EditText text, final View.OnFocusChangeListener listener) {
    text.setOnFocusChangeListener(listener);
}

And in Handler.java write a getter that returns an anonymous class:

public class Handler {
    public View.OnFocusChangeListener getOnFocusChangeListener() {
        return new View.OnFocusChangeListener() {
            @Override
            public void onFocusChange(View view, boolean isFocussed) {
                System.out.print("S");
            }
        };
    }
}

Now in your xml you can pass in the handler like this:

<layout xmlns:tools="http://schemas.android.com/tools"
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto">
    <data>
        <variable name="handler" type="Handler" />
    </data>
    <EditText app:onFocusChange="@{handler.OnFocusChangeListener}"/>
</layout>

Answer 2

We can't set focus change listener of editext in xml file like onclick listener. We need to do it in Java file only.

edit_Text.setOnFocusChangeListener(new OnFocusChangeListener() {
@Override
public void onFocusChange(View v, boolean hasFocus) {
    if(hasFocus){
        Toast.makeText(getApplicationContext(), "got the focus", Toast.LENGTH_LONG).show();
    }else {
        Toast.makeText(getApplicationContext(), "lost the focus", Toast.LENGTH_LONG).show();
    }
   }
});