apps/OboeTester/app/src/main/res/layout/activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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:orientation="vertical"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.google.sample.oboe.manualtest.MainActivity">

    <TextView
        android:id="@+id/versionText"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="V?" />

    <Button
        android:id="@+id/buttonTestOutput"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:onClick="onLaunchTestOutput"
        android:text="Test Output" />

    <Button
        android:id="@+id/buttonTestInput"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:onClick="onLaunchTestInput"
        android:text="Test Input" />

    <Button
        android:id="@+id/buttonTapToTone"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:onClick="onLaunchTapToTone"
        android:text="Tap to Tone Latency" />

    <Button
        android:id="@+id/buttonRecorder"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:onClick="onLaunchRecorder"
        android:text="Record and Play" />

    <Button
        android:id="@+id/buttonEcho"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:onClick="onLaunchEcho"
        android:text="Echo Input to Output" />

    <Button
        android:id="@+id/button_rt_latency"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:onClick="onLaunchRoundTripLatency"
        android:text="Round Trip Latency" />

    <Button
        android:id="@+id/button_manual_glitches"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:onClick="onLaunchManualGlitchTest"
        android:text="Manual Glitch Test" />

    <Button
        android:id="@+id/button_auto_glitches"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:onClick="onLaunchAutoGlitchTest"
        android:text="Auto Glitch Test" />

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal">

        <CheckBox
            android:id="@+id/useCallback"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginRight="30sp"
            android:text="Use Callback"
            android:checked="true"
            android:onClick="onUseCallbackClicked"
            />

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Size:" />

        <EditText
            android:id="@+id/callbackSize"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:ems="10"
            android:text="0"
            android:inputType="number" />

    </LinearLayout>

    <CheckBox
        android:id="@+id/setSpeakerphoneOn"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginRight="30sp"
        android:text="call setSpeakerphoneOn()"
        android:checked="false"
        android:onClick="onSetSpeakerphoneOn"
        />

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Mode:" />

        <Spinner
            android:id="@+id/spinnerAudioMode"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:entries="@array/audio_modes"
            android:prompt="@string/audio_mode_prompt" />

    </LinearLayout>


    <TextView
        android:id="@+id/deviceView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:lines="1"
        android:text="@string/init_device" />

    <TextView
        android:id="@+id/text_build_info"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:ems="10"
        android:text="V?" />

</LinearLayout>