Center a textview vertical to a EditText

What I'm trying to do is have a TextView, and to the right of it an editText that takes up the rest of the space. The textView should be centered vertically along the editText. Now I can do this using an linearlayout, however I would prefer to do it in a relativelayout.

<RelativeLayout
     xmlns:android="http://schemas.android.com/apk/res/android"
     android:layout_width="wrap_content"
     android:layout_height="wrap_content"
     android:padding="10dp">
     <TextView
          android:id="@+id/loginText"
          android:layout_width="wrap_content"
          android:layout_height="wrap_content"
          android:text="Login:"
          android:paddingRight="20dp" />

<EditText开发者_StackOverflow中文版
          android:id="@+id/login"
          android:layout_width="fill_parent"
          android:layout_height="wrap_content"
          android:layout_toRightOf="@id/loginText" />

</RelativeLayout>

What you want to do is possible by using the android:layout_alignBottom and android:layout_alignTop properties provided by the RelativeLayout to its children and the android:gravity property of the TextView.

These properties allow you to set the bottom/top edge of a view to match the bottom/top edge of another view. By applying them to the TextView you can effectively make the TextView match the height of the EditText control. Then, with the gravity property you can make the text in the TextView center vertically inside the TextView control.

The following example should work as you intended:

<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"
    android:padding="5dp" >
    <TextView android:id="@+id/user_name_label"
        android:text="@string/user_name"
        android:layout_width="wrap_content"
        android:layout_height="0dp" 
        android:layout_alignBottom="@+id/user_name_text"
        android:layout_alignTop="@id/user_name_text"
        android:layout_marginRight="5dp"
        android:gravity="center_vertical" />
    <EditText android:id="@id/user_name_text"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_alignParentTop="true"
        android:layout_alignParentRight="true"
        android:layout_toRightOf="@id/user_name_label" />
</RelativeLayout>

add android:layout_gravity="center_vertical" to your Textview

this would place the textview centered vertically in the parent