Android on Micha Kops' Tech Notes

Factory Reset for Google Pixel-C Android Tablet

Sun, 13 Jun 2021 00:00:00 +0200

Steps

Reboot the system by pressing "Power" and "Volume down" simultaneously
Boot menu should appear, use "Volume up/down" to select the menu item "Android Recovery", "Power" to confirm
System reboots, a screen appears with a message "No command" - this is no error though it looks like one
Press "Power" and "Volume up" together and a menu "Android Recovery" appears
Use "Volume up/down" to select the menu item "Wipe data/factory reset", "Power" to confirm
User data on the device is deleted and the original meu is shown
Select the menu item "Reboot system now" and confirm by pressing the "Power" Button
The device reboots and you may configure the Android system …

Quick Mobile Application Prototyping with Ionic Creator

Tue, 17 Nov 2015 00:00:00 +0100

When it comes to the field of hybrid mobile application development, Ionic and its tool-stack is often an attractive choice.

Now there is Ionic Creator to speed up the development process offering an in-browser editor to create user interfaces via drag and drop and supporting basic templates for mobile applications like tabbed layouts etc.

In addition, a project created with this tool may be downloaded and started with easy and that’s what I’d like to show in the following short example.

Creating a hybrid mobile Application with Ionic, Cordova and AngularJS

Sun, 03 May 2015 00:00:00 +0200

Nowadays in the realm of hybrid mobile application development there is a variety of available frameworks worth having a look at.

In the following tutorial I’d like to demonstrate the development life-cycle for a complete mobile application using Ionic, Cordova and AngularJS (and others) covering every step from the initial project setup, creating Angular Controllers, Directives, adding Cordova Plug-Ins, running and testing the application in the browser and emulator up to finally running the application on an Android device and assembling files for a release.

Using the Android Daydream API

Tue, 22 Jan 2013 00:00:00 +0100

Daydream is the new interactive screensaver mode that was added in the Android 4.2 / Jelly Beans release. Such “dreams” may be activated when the device is in idle mode or inserted into a dock.

In the following tutorial we’re going to create a simple daydream that starts a simple animation and in addition we’ll be adding a configuration screen to alter the behaviour of this daydream.

Create a new Android Application

First of all we need a new android project. I am using Eclipse and the ADT plugin here but any other solution like using a specific Maven archetype and the Jayway Maven plugin or using SBT should work, too.

Using the Android Fragment API in a Tablet App

Sun, 18 Mar 2012 00:00:00 +0100

Since I got a new tablet running Android 4.0 aka ice cream sandwich I wanted to play around a bit with the fragments API and creating an application for a tablet.

In the following tutorial, we’re going to build an application that renders several articles from a popular tech blog (just kidding) in a web view.

What to build

We’re going to build an application that is able to display web links in the left section of the screen and when clicked, displaying the corresponding website content in the right section of the application screen.

Writing Styles and Themes on Android

Sat, 03 Dec 2011 00:00:00 +0100

Using reusable styles and themes to modify an Android application’s look is really easy and helps to not violate thy DRY (don’t repeat yourself) principle by typing styles in every single UI element again and again.

In the following tutorial we’re going to write and apply some simple styles and a finally theme to a simple Android application.

Prerequisites

The following environment is needed to follow this tutorial …

Java Development Kit 6
Android SDK
An AVM with at least Android 2.2 / API Version 8
I recommend using Eclipse with the ADT Plugin installed

Managing Background Tasks on Android using the Alarm Manager

Sun, 27 Nov 2011 00:00:00 +0100

In today’s tutorial we’re going to take a look on how to handle periodically scheduled tasks on our Android device by using BroadcastReceivers, Services and the AlarmManager.

Prerequisites

The following environment is needed to follow this tutorial …

Java Development Kit 6
Android SDK
An AVM with at least Android 2.2 / API Version 8
I recommend using Eclipse with the ADT Plugin installed

The Concept

We’re going to create a first broadcast receiver that gets initiated at boot time. This component then should make use of Android’s AlarmManager API and schedule a cyclic task using an explicit intent.

Android Widget Tutorial: Creating a screen-lock Widget in a few steps

Thu, 06 Oct 2011 00:00:00 +0200

In today’s Android tutorial we’re going to take a look at Android’s Widget API and how to make a widget interact with a service using intents.

Figure 1. hasCode Android Widget Tutorial Logo

We’re going to create a fully functional application that allows us to enable or disable our smartphone’s screen lock settings using a widget that can be placed on our home screen.

Finally, I am going to show how to use a smartphone to test and debug our application and connect it to the IDE.

Playing around with the Android Animation Framework

Mon, 27 Sep 2010 00:00:00 +0200

Animations add some spice to our Android applications and the offered animation framework makes it easy to create custom animations and tweens.

So lets dance around and create some animations ;) ..

About

There are two ways to create animations – via XML declaration or in a Java class. We’re going to focus on XML declaration – if you’re interested in java based declaration – take a look at the Android JavaDocs and the subclasses of android.view.animation.Animation.

How to create an Android App using Google’s App Inventor

Wed, 04 Aug 2010 00:00:00 +0200

Today we’re going to take a look at Google’s App Inventor feature that offers programming-novices a nice possibility to enter the fabulous world of Android App programming without deeper knowledge of the API or complex SDK installations.

So lets build some stuff ..

Prerequisites

Java 6 JDK
App Inventors Extras Software
A Google App Inventor Beta Account – request one here

What we are going to build

We are building a simple GUI with a Textbox and a button
A click on the button starts an event that queries the acceleration sensor for coordinates
If the sensor is active and enabled then the coordinates are displayed in the text box

Sensor Fun: Location Based Services and GPS for Android

Sun, 30 May 2010 00:00:00 +0200

The Android SDK offers a nice API to receive information about available providers for location based services and get the current location and coordinates.

In this short tutorial we’re going to build a small activity that displays a list of available location providers and shows the current position using GPS services.

Example Application

Create a new Android Project using ADT and your IDE with a package named com.hascode.android.location_app

Add the permissions needed to the AndroidManifest.xml – it should look like this

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
	package="com.hascode.android.location_app" android:versionCode="1"
	android:versionName="1.0">
	<application android:icon="@drawable/icon" android:label="@string/app_name">
		<activity android:name=".LocationActivity" android:label="@string/app_name">
			<intent-filter>
				<action android:name="android.intent.action.MAIN" />
				<category android:name="android.intent.category.LAUNCHER" />
			</intent-filter>
		</activity>

	</application>
	<uses-sdk android:minSdkVersion="7" />

	<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"></uses-permission>
	<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"></uses-permission>
	<uses-permission android:name="android.permission.ACCESS_LOCATION_EXTRA_COMMANDS"></uses-permission>
	<uses-permission android:name="android.permission.ACCESS_MOCK_LOCATION"></uses-permission>
</manifest>

Android Gestures

Fri, 21 May 2010 00:00:00 +0200

Since version 1.6 Android offers a library for recognition and handling of new gestures using a touch display. With the gesture builder it is possible to capture new gestures in the emulator. Gestures can be integrated into an activity like that.

GestureLibrary gLib = GestureLibraries.fromRawResource(this, R.raw.spells);
if (!gLib.load()) {
  finish();
}

Furthermore we need a gesture overlay in the UI:

 <android.gesture.GestureOverlayView
    android:id="@+id/gestures"
    android:layout_width="fill_parent"
    android:layout_height="0dip"
    android:layout_weight="1.0" />

In the next step we implement an event handler for the gesture (Source: http://developer.android.com/resources/articles/gestures.html):

GestureOverlayView gestures = (GestureOverlayView) findViewById(R.id.gestures);
gestures.addOnGesturePerformedListener(this);

public void onGesturePerformed(GestureOverlayView overlay, Gesture gesture) {
 ArrayList<prediction> predictions = mLibrary.recognize(gesture);

   if (predictions.size() > 0) {
     Prediction prediction = predictions.get(0);
     if (prediction.score > 1.0) {
       Toast.makeText(this, prediction.name, Toast.LENGTH_SHORT).show();
     }
   }
 }

Creating a simple Gesture App with Android

Fri, 14 May 2010 00:00:00 +0200

The integration of gestures into your android app adds some nice functionality and is made very easy using Google’s GestureBuilder application and the integrated GestureLibrary and Gesture Overlay API – so let’s build a sample app.

If you need some basic information regarding gestures on android first – take a look at this article.

Creating a gesture library

First you need to define the gestures that should be captured in the application later. For this reason there’s the GestureBuilder delivered with the Android SDK. You can find the app in the samples directory of your android sdk – e.g. <installation-directory>/android-sdk-linux_86/platforms/android-2.1/samples/GestureBuilder.

Playing around with QR Codes

Tue, 11 May 2010 00:00:00 +0200

Sometimes QR codes are a nice way to distribute information like calendar events, contact information, e-mail, geo-locations or internet addresses.

In the following article we’re going to encode information to QR code images using the ZXing library and afterwards decode information from a given QR code.

Finally we’re taking a look on online QR code generators and how to integrate the ZXing library in a Maven project.

The ZXing Library

Download the ZXing Libraries from http://code.google.com/p/zxing/downloads/list – the file name is ZXing-<version>.zip
Unpack the downloaded archive somewhere
Change to the extracted directory and run ant. If you don’t have JavaME installed – and you don’t have to for the samples below – run ant buildwithoutj2me – that will do the job
Having compiled the libraries you’re now free to include the core.jar from zxing-<version>/core/ and the javase.jar from zxing-<version>/javase as dependency in your project

Sensor Fun: Creating a simple audio recorder/player

Sun, 02 May 2010 00:00:00 +0200

Sound recording and playback is really simple using the MediaRecorder and MediaPlayer classes .. see the example below ..

Sample App

First some layout .. a button to start/stop recording and a button to play the recorded stuff (main.xml):

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    >
<TextView
	android:id="@+id/output"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:text=""
    />
<Button android:text="@+string/record" android:id="@+id/btRecord" android:layout_width="wrap_content" android:layout_height="wrap_content"></Button>
<Button android:text="@+string/play" android:id="@+id/btPlay" android:layout_width="wrap_content" android:layout_height="wrap_content"></Button>
</LinearLayout>

Adjusting the externalized strings in the strings.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <string name="app_name">Soundrecorder Tutorial</string>
	<string name="record">Record!</string>
	<string name="play">Play</string>
</resources>

Sensor Fun: Using the accelerometer on Android

Tue, 27 Apr 2010 00:00:00 +0200

Here is an example on how to use the accelerometer in your Android application. If you want to simulate the acceleration on the emulator I highly recommend the Sensor Simulator on the OpenIntents website.

The following example app displays the coordinates received by the sensor.

The Acceleration App

The activity – AccelerationActivity.java

package com.hascode.android;

import android.app.Activity;
import android.content.Context;
import android.hardware.Sensor;
import android.hardware.SensorEvent;
import android.hardware.SensorEventListener;
import android.hardware.SensorManager;
import android.os.Bundle;
import android.widget.TextView;

public class AccellerationActivity extends Activity {
	private TextView result;
	private SensorManager sensorManager;
	private Sensor sensor;
	private float x, y, z;

	@Override
	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.main);

		sensorManager = (SensorManager) getSystemService(Context.SENSOR_SERVICE);
		sensor = sensorManager.getSensorList(Sensor.TYPE_ACCELEROMETER).get(0);

		result = (TextView) findViewById(R.id.result);
		result.setText("No result yet");
	}

	private void refreshDisplay() {
		String output = String
				.format("x is: %f / y is: %f / z is: %f", x, y, z);
		result.setText(output);
	}

	@Override
	protected void onResume() {
		super.onResume();
		sensorManager.registerListener(accelerationListener, sensor,
				SensorManager.SENSOR_DELAY_GAME);
	}

	@Override
	protected void onStop() {
		sensorManager.unregisterListener(accelerationListener);
		super.onStop();
	}

	private SensorEventListener accelerationListener = new SensorEventListener() {
		@Override
		public void onAccuracyChanged(Sensor sensor, int acc) {
		}

		@Override
		public void onSensorChanged(SensorEvent event) {
			x = event.values[0];
			y = event.values[1];
			z = event.values[2];
			refreshDisplay();
		}

	};
}

First steps on Android: Creating a simple Todo App

Mon, 26 Apr 2010 00:00:00 +0200

In this tutorial we are going to build a simple todo app that is able to store simple todos in a database. The user is able to add new todos or delete old ones by clicking on a todo. For this tutorial we won’t use maven to keep it simple – if maven integration is desired – take a look at this tutorial.

Steps

Create a new android project using the Android SDK and your IDE
Create some packages com.hascode.android.activity and com.hascode.android.persistence

Create the layout in res/layout/main.xml – the main elements: a listview for the todos-list, a textbox and a button to enter new data.

<?xml version="1.0" encoding="utf-8"?>
    <RelativeLayout
        android:id="@+id/widget31"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        xmlns:android="http://schemas.android.com/apk/res/android"
    >
        <TableRow
            android:id="@+id/row"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:orientation="horizontal"
            android:layout_below="@+id/tasklist"
            android:layout_alignParentLeft="true"
        >
            <EditText
                android:id="@+id/etNewTask"
                android:layout_width="200px"
                android:layout_height="wrap_content"
                android:text=""
                android:textSize="18sp"
            >
            </EditText>
            <Button
                android:id="@+id/btNewTask"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="@+string/add_button_name"
            >
            </Button>
        </TableRow>
        <ListView
            android:id="@+id/tasklist"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:layout_alignParentTop="true"
            android:layout_alignParentLeft="true"
        >
        </ListView>
</RelativeLayout>

Signing APK with the Maven-Jar-Signer Plugin

Sat, 17 Apr 2010 00:00:00 +0200

There is a nice Maven plugin helping you signing your Android app – the Maven Jar Signer Plugin. If you want to learn more about Maven integration in an android project take a look at this article.

Maven Profile Setup

Add the following code to your pom.xml

<?xml version="1.0"?>
<profiles>
    <profile>
        <id>sign</id>
        <build>
            <plugins>
                <plugin>
                    <groupId>org.apache.maven.plugins</groupId>
                    <artifactId>maven-jarsigner-plugin</artifactId>
                    <version>1.2</version>
                    <executions>
                        <execution>
                            <id>signing</id>
                            <goals>
                                <goal>sign</goal>
                            </goals>
                            <phase>package</phase>
                            <inherited>true</inherited>
                            <configuration>
                                <archiveDirectory/>
                                <includes>
                                    <include>target/*.apk</include>
                                </includes>
                                <keystore>path/to/keystore</keystore>
                                <storepass>storepasword</storepass>
                                <keypass>keypassword</keypass>
                                <alias>key-alias</alias>
                            </configuration>
                        </execution>
                    </executions>
                </plugin>
                <plugin>
                    <groupId>com.jayway.maven.plugins.android.generation2</groupId>
                    <artifactId>maven-android-plugin</artifactId>
                    <inherited>true</inherited>
                    <configuration>
                        <sign>
                            <debug>false</debug>
                        </sign>
                    </configuration>
                </plugin>
            </plugins>
        </build>
    </profile>
</profiles>

How to integrate Android Development Tools and Maven

Fri, 02 Apr 2010 00:00:00 +0200

With the Maven Android Plugin it is possible to build and deploy/undeploy your android app and start/stop the emulator – if you’re used to maven you won’t be going without it ;)

If you’re interested in signing your apk using maven – take a look at this article

Project Setup

Create an android project using the android tool

We need some dependencies – so create a pom.xml in the project’s root directory – I took this from the plugin samples and modified it:

<?xml version="1.0" encoding="UTF-8"?>
<!--
 Copyright (C) 2009 Jayway AB

 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
 You may obtain a copy of the License at

 http://www.apache.org/licenses/LICENSE-2.0

 Unless required by applicable law or agreed to in writing, software
 distributed under the License is distributed on an "AS IS" BASIS,
 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 See the License for the specific language governing permissions and
 limitations under the License.
-->
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
     <modelVersion>4.0.0</modelVersion>
     <groupId>com.hascode.android.app</groupId>
     <artifactId>demo</artifactId>
     <packaging>apk</packaging>
     <name>hasCode.com - Sample Android App using the Maven Android Plugin</name>
     <version>0.1</version>
     <dependencies>
         <dependency>
             <groupId>android</groupId>
             <artifactId>android</artifactId>
             <version>2.1</version>
             <scope>provided</scope>
         </dependency>

         <dependency>
             <groupId>junit</groupId>
             <artifactId>junit</artifactId>
             <version>4.8.1</version>
             <scope>test</scope>
         </dependency>
     </dependencies>

     <build>
         <!--<finalName>${artifactId}</finalName>-->
         <plugins>
             <plugin>
                 <groupId>com.jayway.maven.plugins.android.generation2</groupId>
                 <artifactId>maven-android-plugin</artifactId>
                 <configuration>
                     <sdk>
                         <path>${env.ANDROID_HOME}</path>
                         <platform>3</platform>
                     </sdk>
                     <deleteConflictingFiles>true</deleteConflictingFiles>
                 </configuration>
                 <extensions>true</extensions>
             </plugin>

             <plugin>
                 <artifactId>maven-compiler-plugin</artifactId>
                 <configuration>
                 <source>1.5</source>
                 <target>1.5</target>
                 </configuration>
             </plugin>

         </plugins>
     </build>

</project>