android-databinding-binding-pass-object-to-customview.md

title: Android: Simpler passing objects to custom views with databinding tags: android,android-databinding,android-custom-views

If you have a custom view, you can pass an object to it via databinding. Let's say you have this basic custom view.

public class CustomV extends Button {

  public static class APojo {
    private String oj;

    public String getOj() {
     return oj;
    }

    public void setOj(String oj) {
     this.oj = oj;
     }
  }

  private APojo thing;

  public CustomV(Context context) {
    super(context);
    init(null, 0);
  }

  public CustomV(Context context, AttributeSet attrs) {
    super(context, attrs);
    init(attrs, 0);
  }

  public CustomV(Context context, AttributeSet attrs, int defStyle) {
    super(context, attrs, defStyle);
    init(attrs, defStyle);
  }

  private void init(AttributeSet attrs, int defStyle) {
    setText("Custom innit");
  }

  public APojo getThing() {
    return thing;
  }

  public void setThing(APojo thing) {
    this.thing = thing;
  }
}

It's a basic custom view class, with a basic pojo class at at the top, a class variable and a getter and setter for that.

Now initialise this custom view:

<com.example.CustomV
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
  app:thing="@{somevar.someinstance}"
/>

The somevar is just a databinding variable instance you have. someinstance is an instance of the APojo class. And the app: namespace is the standard xml:app="http://schemas.android.com/apk/res-auto".

Now when you initalise that view, the setThing method in your custom view will be called.