Difference between aar vs jar. And how to implement aar in Android

Although .jar and .aar files are very similar but still there are few differences between them :

1. .jar stands for Java Archive and .aar stands for Android archive.

2.  A Jar file is basically a zip-file which contains one or many class files and text files containing some sort of meta data. Jar files can be used to bundle java library containing many classes into single file. Where as .aar files are same as .jar but their also contains android stuff like source files, layouts, drawable and manifest files as a would module contains.

3. Except Android Studio the rest of the world does not know what is that thing aar file unlike jar files.

How to compile a .aar file in your android project

Add .aar file to libs folders under your module

1. Add below code snippet to your project level gradle file

// Top-level build file where you can add configuration options common to all sub-projects/modules.

buildscript {
    repositories {
        jcenter()
        flatDir {
            dirs 'aars','libs'
        }
    }

    dependencies {
        classpath 'com.android.tools.build:gradle:2.2.2'
        // NOTE: Do not place your application dependencies here; they belong
        // in the individual module build.gradle files
    }
}

allprojects {
    repositories {
        jcenter()
    }
}

task clean(type: Delete) {
    delete rootProject.buildDir
}

2. Below code to your module level gradle

  compile(name:'name of the aar file here', ext:'aar')

Cheers!!

How to add a common header across all activities using Parent-Child Relationship

This blog post demonstrates how to add a common header layout in all our Android Activities using simple Parent-Child Relationship.

Note : you can add Fragments as well in the container i am using in the parent class to have one activity and multiple fragments as per your app architecture.

My use case was to implement a common header in an existing project with 50+ activities which shows a to line header with a message whether a user is online or offline without changing to much in the existing code.  

1. BaseActivity.java

package kamal.com.headtest;

import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.FrameLayout;
import android.widget.LinearLayout;
import android.widget.RelativeLayout;
import android.widget.TextView;

public class BaseActivity extends AppCompatActivity {

    private TextView tvHeader,tvClose;
    private FrameLayout activityContainer;
    private RelativeLayout rlHeaderView;

    @Override
    public void setContentView(int layoutResID) {
        LinearLayout llparentView = (LinearLayout) getLayoutInflater().inflate(R.layout.activity_main, null);
        initViews(llparentView);
        getLayoutInflater().inflate(layoutResID, activityContainer, true);
        super.setContentView(llparentView);
    }

    /**
     *  Initialize BaseActivity Views
     * @param view : parent use to initialize child views
     */
    private void initViews(View view){
        tvHeader=(TextView)view.findViewById(R.id.headertext);
        tvClose=(TextView)view.findViewById(R.id.closebtn);
        activityContainer = (FrameLayout) view.findViewById(R.id.activity_content);
        rlHeaderView=(RelativeLayout)view.findViewById(R.id.headerviewrl);
        tvClose.setOnClickListener(closeBtnListener);
    }


    /**
     *  anonymous onclicklistener to handle a click event for Close button in header.
     */
    private View.OnClickListener closeBtnListener=new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            finish();
        }
    };

    /**
     *  Method to be overiden by child classes if need to hide header view
     * @param show : true or false as to handle visibility of the header
     */
    public void showHeader(boolean show){
        rlHeaderView.setVisibility(show ? View.VISIBLE : View.GONE);
    }

    /**
     *  Method to be overiden by child classes if need to hide header view
     * @param value : of the header
     */
    public void setHeaderText(String value){
        tvHeader.setText(value);
    }
}

2. ChildActivity.java

package kamal.com.headtest;

import android.os.Bundle;
import android.support.annotation.Nullable;

public class ChildActivity extends BaseActivity{

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        super.setContentView(R.layout.childlayout);
        showHeader(true);;
    }
}

3. activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/parent_view"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <RelativeLayout
        android:id="@+id/headerviewrl"
        android:layout_width="match_parent"
        android:orientation="horizontal"
        android:layout_height="?actionBarSize">

        <TextView
            android:id="@+id/headertext"
            android:layout_width="wrap_content"
            android:layout_height="?actionBarSize"
            android:layout_centerHorizontal="true"
            android:gravity="center"
            android:padding="10dp"
            android:textSize="20sp"
            android:textStyle="bold"
            android:text="My Header View" />

        <TextView
            android:id="@+id/closebtn"
            android:layout_width="wrap_content"
            android:layout_height="?actionBarSize"
            android:gravity="center"
            android:padding="10dp"
            android:textSize="30sp"
            android:textStyle="bold"
            android:layout_alignParentRight="true"
            android:text="X" />

    </RelativeLayout>

    <View
        android:layout_width="match_parent"
        android:layout_height="2dp"
        android:background="#000000"
        />

    <FrameLayout
        android:id="@+id/activity_content"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />

</LinearLayout>

4. childlayout.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:layout_width="match_parent"
    android:layout_height="match_parent">
 
    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:padding="10dp"
        android:layout_marginTop="10dp"
        android:layout_centerHorizontal="true"
        android:text="Testing child" />

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:padding="10dp"
        android:layout_marginTop="10dp"
        android:layout_centerHorizontal="true"
        android:text="Testing child" />

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:padding="10dp"
        android:layout_marginTop="10dp"
        android:layout_centerHorizontal="true"
        android:text="Testing child" />

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:padding="10dp"
        android:layout_marginTop="10dp"
        android:layout_centerHorizontal="true"
        android:text="Testing child" />

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:padding="10dp"
        android:layout_marginTop="10dp"
        android:layout_centerHorizontal="true"
        android:text="Testing child" />

</LinearLayout>

5. manifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="kamal.com.headtest">

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".ChildActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>
</manifest>

Output:






Cheers :-)