get parent's view from a layout

Question

I have a FragmentActivity with this layout:

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent" >

<TextView
    android:id="@+id/textView1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="@string/menulabel"
    android:textSize="24sp" />

<EditText
    android:id="@+id/editText1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:ems="10"
    android:inputType="text"
    android:layout_below="@+id/textView1"
    android:hint="@string/search_title_hint" />

<TextView
    android:id="@+id/textView2"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="@string/spinnersearch"
    android:layout_below="@+id/editText1" />

<LinearLayout
    android:id="@+id/layout1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_below="@+id/textView2" >

    <Spinner
        android:id="@+id/spinner_search"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:prompt="@string/spinnersearch" />

    <Button
        android:id="@+id/button1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/reset_search" />

</LinearLayout>

<Button
    android:id="@+id/button2"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="@string/buttonnewcat"
    android:layout_below="@+id/layout1" />

<Button
    android:id="@+id/button3"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="@string/buttondelcat" 
    android:layout_below="@+id/button2" />

<Button
    android:id="@+id/button4"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="@string/buttoneditcat"
    android:layout_below="@+id/button3" />

<Button
    android:id="@+id/button5"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="@string/buttonnewtext"
    android:layout_below="@+id/button4" />

<Button
    android:id="@+id/button6"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="@string/buttondeltext"
    android:layout_below="@+id/button5" />

<RelativeLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent" >

    <side.menu.scroll.ScrollerLinearLayout
        android:id="@+id/menu_content_side_slide_layout"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical" >

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="45dp"
            android:background="@drawable/ab_solid_example"
            android:orientation="horizontal" >

            <ImageView
                android:id="@+id/main_tmp_button"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:background="@drawable/actionbar_background"
                android:src="@drawable/download" />

        </LinearLayout>
        <FrameLayout
            android:id="@+id/fragment_container"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:background="@drawable/bg_groud" />

    </side.menu.scroll.ScrollerLinearLayout>
</RelativeLayout>

and the ScrollerLinearLayout class is something like this:

public class ScrollerLinearLayout extends LinearLayout {
    // code of the class
}

How to access from ScrollerLinearLayout to the parent layout to get - for example - the editetxt? FragmentActivity and ScrollerLineraLayout are in different packages of the same projects. I tried to use the getParent() function in this way within the ScrollerLinearLayout but it doesn't work.

RelativeLayout r = (RelativeLayout) this.getParent().getParent();
int w = r.findViewById(R.id.editText1).getLayoutParams().width;

Someone help me? Thanks!

Answer 1

The getParent method returns a ViewParent, not a View. You need to cast the first call to getParent() also:

RelativeLayout r = (RelativeLayout) ((ViewGroup) this.getParent()).getParent();

As stated in the comments by the OP, this is causing a NPE. To debug, split this up into multiple parts:

ViewParent parent = this.getParent();
RelativeLayout r;
if (parent == null) {
    Log.d("TEST", "this.getParent() is null");
}
else {
    if (parent instanceof ViewGroup) {
        ViewParent grandparent = ((ViewGroup) parent).getParent();
        if (grandparent == null) {
            Log.d("TEST", "((ViewGroup) this.getParent()).getParent() is null");
        }
        else {
            if (parent instanceof RelativeLayout) {
                r = (RelativeLayout) grandparent;
            }
            else {
                Log.d("TEST", "((ViewGroup) this.getParent()).getParent() is not a RelativeLayout");
            }
        }
    }
    else {
        Log.d("TEST", "this.getParent() is not a ViewGroup");
    }
}

//now r is set to the desired RelativeLayout.