When should one use android:clickable?

As the documentation states, and as far as I know :

clickable - Defines whether this view reacts to click events. Must be a boolean value, either "true" or "false".

So for example if you just declare a Webview or View in your layout.xml and try to set an OnClickListener on this views the OnClick event won't be fired unless you specify the attribute :

  android:clickable=true

clickable seems to be useful when you need a view to consume clicks so that they do not go to views beneath the top view.

For example, I have a FrameLayout that I display over an underlying RelativeLayout at certain times. When the user would click on an underlying EditText the focus would shift to that EditText. Really annoying when the FrameLayout was still being shown. Now the user doesn't know why a keyboard just popped up or where they are typing.

When I set clickable="true" in the FrameLayout, users could no longer accidentally click underlying EditText fields.

<RelativeLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    ...>
    <EditText>
    <EditText>
    <EditText>
    <!-- FrameLayout with grayed-out background. -->
    <FrameLayout
        android:id="@+id/sometimes_visible_view"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="#80808080"
        android:clickable="true"
        android:visibility="gone"
        android:focusable="true"
        ...>
        <LinearLayout
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="center"
            ...>
            <View>
            <View>
        </LinearLayout>
    </FrameLayout>
</RelativeLayout>

When you are setting view.setOnClickListener on any View, eg: myButton.setOnClickListener(new OnClickListener) by default it is considered as clickable="true".

So you would not need to mention that in the XML file like android:clickable="true". The onClick() event will be fired without using android:clickable="true".