android - Right Align button in horizontal LinearLayout

Question

If you look at the attached image. I need my button to be right aligned but for some reason it's not working with 'gravity:right'...

Here's my code for that layout:

<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:orientation="horizontal"
    android:layout_marginTop="35dp">

    <TextView
        android:id="@+id/lblExpenseCancel"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/cancel"
        android:textColor="#404040"
        android:layout_marginLeft="10dp"
        android:textSize="20sp"
        android:layout_marginTop="9dp" />

    <Button
        android:id="@+id/btnAddExpense"
        android:layout_width="wrap_content"
        android:layout_height="45dp"
        android:background="@drawable/stitch_button"
        android:layout_marginLeft="10dp"
        android:text="@string/add"
        android:layout_gravity="right"
        android:layout_marginRight="15dp" />

</LinearLayout>

Why is no working?!

Answer 1

Single LinearLayout solution. Only adding a simple spacing view:
(No-one seemed to have mentioned this one, only more complicated multi-layout solutions.)

<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:orientation="horizontal"
    android:layout_marginTop="35dp">

    <TextView
        android:id="@+id/lblExpenseCancel"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/cancel"
        android:textColor="#404040"
        android:layout_marginLeft="10dp"
        android:textSize="20sp"
        android:layout_marginTop="9dp" />

    <!-------------------------  ADDED SPACER VIEW -------------------->
    <View
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:layout_weight="1"
        />
    <!------------------------- /ADDED SPACER VIEW -------------------->

    <Button
        android:id="@+id/btnAddExpense"
        android:layout_width="wrap_content"
        android:layout_height="45dp"
        android:background="@drawable/stitch_button"
        android:layout_marginLeft="10dp"
        android:text="@string/add"
        android:layout_gravity="right"
        android:layout_marginRight="15dp" />

</LinearLayout>

Note the "highlighted" View, I didn't modify anything else. Height=0 makes sure it's not visible. Width=0 is because the width is determined by the LinearLayout based on weight=1. This means that the spacer view will stretch as much as possible in the direction (orientation) of the LinearLayout.

Note that you should use android.widget.Space or android.support.v4.widget.Space instead of View if your API level and/or dependencies allow it. Space achieves the job in a cheaper way, because it only measures and doesn't try to draw anything like View does; it's also more expressive conveying the intention.