使用bringToFont实现标签切换

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:gravity="center"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin">
<FrameLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content">

<ImageView
android:id="@+id/iv_t"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:src="@drawable/t"
android:layout_marginLeft="100dp"
android:scaleType="centerCrop"
/>
<ImageView
android:id="@+id/iv_s"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:src="@drawable/s"
android:layout_marginLeft="50dp"
android:scaleType="centerCrop"
/>
<ImageView
android:id="@+id/iv_f"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:src="@drawable/f"
android:scaleType="centerCrop"
/>
</FrameLayout>
<android.support.design.widget.TextInputLayout
android:id="@+id/username"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_margin="10dp">
<EditText
android:id="@+id/et_username"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
</android.support.design.widget.TextInputLayout>
<android.support.design.widget.TextInputLayout
android:id="@+id/password"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_margin="10dp">
<EditText
android:id="@+id/et_pwd"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
</android.support.design.widget.TextInputLayout>
<Button
android:onClick="login"
android:text="登录"
style="@style/as.a" />
<Switch
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
</LinearLayout>

@Override
public void onClick(View view) {
switch (view.getId()) {
case R.id.iv_f:
ivT.bringToFront();
ivS.bringToFront();
break;
case R.id.iv_s:
ivF.bringToFront();
ivT.bringToFront();
break;
case R.id.iv_t:
ivF.bringToFront();
ivS.bringToFront();
break;
default:break;
}
view.bringToFront();
}