Hello Glass Tutorial

Introduction

Before we start; if your Glass isn’t set up yet, view this page. Otherwise, this assumes that your Glass is set up, you have at least a little bit of technical/programming knowledge, and you’re ready to go. If you’d like to take a look at the fully set up project or take the app for a spin, check out the HelloGlass GitHub repository.

Getting started

First, let’s initialize a new Empty Activity project with the Minimum SDK set to API 19: Android 4.4 (KitKat). Wait for a bit for it to get itself set up, and then we’re ready to move on.

Importing the GDK

To get started, please download the original GDK - here’s the source if you ever want to take a look: GlassKit/gdk - and drag it into the app/libs folder (which can be found by switching the tab at the top left from Android to Project). If the libs folder isn’t in the app directory, you will have to make it.¹ Finally, right click on gdk.jar in the libs folder and select Add as Library from the menu to be able to use it in your project. You will now be able to use the old GDK in whatever version you’re using!

Changes to the default project

Below are a few changes we need to make before we’re ready to run:

AndroidManifest.xml

At the path app/manifests/AndroidManifest.xml, we’re going to tweak just a couple things. Replace the <activity></activity> with what’s below:

<activity  
    android:name="com.{your name}.{project name}.MainActivity"  
    android:enabled="true"  
    android:exported="true">  
    <intent-filter>
        <action android:name="com.google.android.glass.action.VOICE_TRIGGER" />  
    </intent-filter>
    <meta-data android:name="com.google.android.glass.VoiceTrigger"
        android:resource="@xml/show_me_a_demo" />  
</activity>

As mentioned here on step 4, to make sure you don’t blind yourself, remove the following line inside the first <application> tag:

android:theme="@style/Theme.{project name}"

MainActivity.java

At the path app/java/com.{your name}.{project name}/MainActivity.java, we need to change the whole file, essentially. Copy and paste the following in, replacing what’s there already:

package com.{your name}.{project name};

import android.app.Activity;
import android.os.Bundle;

public class MainActivity extends Activity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }
}

activity_main.xml

At the path app/res/layout/activity_main.xml, we’re going to replace everything once again with what’s below:

<?xml version="1.0" encoding="utf-8"?>  
<FrameLayout  
    xmlns:android="http://schemas.android.com/apk/res/android"  
    android:layout_width="match_parent"  
    android:layout_height="match_parent">  
  
    <TextView        android:id="@+id/textView"  
        android:layout_width="match_parent"  
        android:layout_height="match_parent"  
        android:gravity="center"  
        android:text="Hello Glass!" />  
</FrameLayout>

show_me_a_demo.xml (new)

We must make a new file at the path app/res/xml entitled show_me_a_demo.xml, and inside is:

<?xml version="1.0" encoding="utf-8"?>  
<!-- https://glasskit.dev/archive/glass/develop/gdk/reference/com/google/android/glass/app/VoiceTriggers.Command -->  
<trigger command="SHOW_ME_A_DEMO" />

Final steps

To get your code to run on your Glass, you must first navigate to Run > Edit Configurations and then at the bottom under Launch Options, set the Launch parameter to be Specified Activity instead of Default Activity. Below, select com.{your name}.{project name}.MainActivity and then hit Apply.

You should be able to build and run now!

Footnotes