RelativeLayout相对布局

align：对齐

常用属性：

layout_toRightOf：在**的右边

android:layout_toRightOf="@+id/view_3"

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layout_alignBottom：底部和**对齐

android:layout_alignBottom="@+id/view_3"

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layout_below:在**下面

android:layout_below="@+id/ll_1"

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layout_alignParentTop：与外部容器的顶部对齐

android:layout_alignParentTop="true"

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