align_parent_bottom与SquareRelativeLayout的行为不同

Question

我想得到这个

这是我的xml布局

<?xml version="1.0" encoding="utf-8"?>
<android.support.v7.widget.CardView
android:layout_height="wrap_content"
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:elevation="5dp"
app:cardCornerRadius="2dp"
android:layout_margin="2dp"
android:clickable="true"
android:foreground="?attr/selectableItemBackground">
<com.example.akash.music.view.SquareRelativeLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent">
    <ImageButton
        android:id="@+id/img_button_delete"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentRight="true"
        android:layout_gravity="right"
        android:background="?android:selectableItemBackground"
        android:padding="4dp"
        app:srcCompat="@drawable/ic_clear_black" />
    <TextView
        android:padding="4dp"
        android:id="@+id/text"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_vertical"
        android:text="Hello"
        android:textSize="@dimen/text_size_primary" />
    <View
        android:id="@+id/view"
        android:layout_above="@+id/button_apply"
        android:layout_width="match_parent"
        android:layout_height="2dp"
        android:background="@color/colorBackground" />

    <TextView
        android:clickable="true"
        android:padding="8dp"
        android:textStyle="bold"
        android:textSize="@dimen/text_size_primary"
        android:id="@+id/button_apply"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="?attr/selectableItemBackground"
        android:text="APPLY"
        android:gravity="center"
        android:layout_alignParentBottom="true"
        />

    </com.example.akash.music.view.SquareRelativeLayout>
    </android.support.v7.widget.CardView>

这里是SquareRelativeLayout.class

public class SquareRelativeLayout extends RelativeLayout {


public SquareRelativeLayout(Context context) {
    super(context);
}

public SquareRelativeLayout(Context context, AttributeSet attrs) {
    super(context, attrs);
}

public SquareRelativeLayout(Context context, AttributeSet attrs, int defStyleAttr) {
    super(context, attrs, defStyleAttr);
}

@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
    super.onMeasure(widthMeasureSpec, heightMeasureSpec);
    setMeasuredDimension(widthMeasureSpec,widthMeasureSpec);
}
}

问题是我无法将APPLY按钮对齐到SquareRelativeLayout的底部。如果我这样做，它就变得不可见了。