Android XML layout checkbox “onclick” method bind to a function not found in MainActivity

Question

Is it possible in Android to bind the "onclick" method from a checkbox to a function defined in a java class file directly in the XML file?

something like this

//XML layout File

....

 <CheckBox
     android:id="@+id/checkbox_1"
     android:layout_width="wrap_content"
     android:layout_height="wrap_content"
     android:text="@string/testString"
     android:textColor="@color/testcolor"
     android:onClick="onClickCheckbox_1_do"/>

...

public class TestClass{
     ...
     public void onClickCheckbox_1_do(View view) {
        //DoStuff
     }

}

Thanks!

Answer 1

Yes, you can. I just did. Write this code in your layout file:

<CheckBox
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:onClick="click"/>

And in your activity:

public void click(View view)
{
}

Answer 2

Yes. it's possible.

To define the click event handler for a checkbox, you should add android:onClick attribute to the element in your XML layout. The value for this attribute must be the name of the method you want to call in response to a click event. The Activity hosting the layout must then implement the corresponding method.

The method you declare in the android:onClick attribute must have a signature exactly as shown above. Specifically, the method must: 1. Be public 2. Return void, and 3. Define a View as its only parameter (this will be the View that was clicked)

Below is the code examples: xml.

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent">
<CheckBox android:id="@+id/checkbox_meat"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="@string/meat"
    android:onClick="onCheckboxClicked"/>
<CheckBox android:id="@+id/checkbox_cheese"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="@string/cheese"
    android:onClick="onCheckboxClicked"/>
</LinearLayout>

The activity method should look as follows:

  public void onCheckboxClicked(View view) {
// Is the view now checked?
boolean checked = ((CheckBox) view).isChecked();

// Check which checkbox was clicked
switch(view.getId()) {
    case R.id.checkbox_meat:
        if (checked)
            // Put some meat on the sandwich
        else
            // Remove the meat
        break;
    case R.id.checkbox_cheese:
        if (checked)
            // Cheese me
        else
            // I'm lactose intolerant
        break;
    // TODO: Veggie sandwich
  }
}

I hope you find this helpful.