Create two-way binding with Android Data Binding

Question

I have implemented the new Android data-binding, and after implementing realised that it does not support two-way binding. I have tried to solve this manually but I am strug

Answer 1

I struggled to find a full example of 2-way databinding. I hope this helps. The full documentation is here: https://developer.android.com/topic/libraries/data-binding/index.html

activity_main.xml:

Item.java:

import android.databinding.BaseObservable;
import android.databinding.Bindable;

public class Item extends BaseObservable {
    private String name;
    private Boolean checked;
    @Bindable
    public String getName() {
        return this.name;
    }
    @Bindable
    public Boolean getChecked() {
        return this.checked;
    }
    public void setName(String name) {
        this.name = name;
        notifyPropertyChanged(BR.name);
    }
    public void setChecked(Boolean checked) {
        this.checked = checked;
        notifyPropertyChanged(BR.checked);
    }
}

MainActivity.java:

public class MainActivity extends AppCompatActivity {

    public Item item;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        item = new Item();
        item.setChecked(true);
        item.setName("a");

        /* By default, a Binding class will be generated based on the name of the layout file,
        converting it to Pascal case and suffixing “Binding” to it.
        The above layout file was activity_main.xml so the generate class was ActivityMainBinding */

        ActivityMainBinding binding = DataBindingUtil.setContentView(this, R.layout.activity_main);
        binding.setItem(item);
    }

    public void button_onClick(View v) {
        item.setChecked(!item.getChecked());
        item.setName(item.getName() + "a");
    }
}

build.gradle:

android {
...
    dataBinding{
        enabled=true
    }

}