What is Android?

Android OS versions

Architecture

App Components

Activities - screens

Intents - message

Services - background tasks

Content Providers - provide content to other apps 

Broadcast Receivers - receive messages from the OS or other apps

The Manifest file

 <application>
    <activity>
        <intent-filter>
            <action />
            <category />
            <data />
        </intent-filter>
        <meta-data />
    </activity>

    <uses-permission />

    <uses-sdk />
</application>
        

Translation - явен, ясен, очевиден

Contains description of what components your app contains

The R file

package com.apphunt.app;

public final class R {
    public static final class anim {
        public static final int abc_fade_in=0x7f040000;
        public static final int abc_fade_out=0x7f040001;
        public static final int abc_grow_fade_in_from_bottom=0x7f040002;
        public static final int slide_out_top=0x7f040014;
        ...
    }

    public static final class color {
        public static final int abc_background_cache_hint_selector_material_dark=0x7f0d0074;
        public static final int abc_background_cache_hint_selector_material_light=0x7f0d0075;
        ...
    }

    public static final class dimen {
        public static final int ab_elevation=0x7f080015;
        public static final int ab_shadow_height=0x7f080016;
        ...
    }

    public static final class layout {
        public static final int abc_action_bar_title_item=0x7f030000;
        ...
    }
}

Gradle

What gradle gives you?

1. Customize, configure, extend build process - (Groovy)
2. Create multiple APKs with different features
3. Reuse code and resources
4. Great maven integration

compileSdkVersion 19
buildToolsVersion "19.0.0"

defaultConfig {
    minSdkVersion 8
    targetSdkVersion 19
    versionCode 1
    versionName "1.0"
}

dependencies {
    compile project(":lib")
    compile 'com.android.support:appcompat-v7:19.0.1'
    compile fileTree(dir: 'libs', include: ['*.jar'])
}

app/build.gradle

Building & Running

Decompilation needs:

or Android APK Decompiler

• Dex2Jar
• ApkTool
• JD-GUI

Let's decompile

What is an Activity?

activity_main.xml

<RelativeLayout>

<Button />

</RelativeLayout>

MainActivity.java

onCreate(Bundle bundle) {

  setContentView(R.layout.activity_main)

}

Activity Lifecycle

Passing data between activities

Intent intent = new Intent(this, 
                           Activity2.class)
startActivity(intent)

Intent types

Explicit - specific component

Implicit - Unkown component

Receiving data from other apps

Intent Filters

 <!-- This activity handles "SEND" actions with text data -->
<intent-filter>
    <action android:name="android.intent.action.SEND"/>
    <category android:name="android.intent.category.DEFAULT"/>
    <data android:mimeType="text/plain"/>
</intent-filter>

Let's code