Things every android developer should know - part 5

Description: Hello coders! In this post I'm gonna show some interesting tips and tricks you can start using in your android project.

Also check out Part 1,Part 2, Part 3 and Part 4

So let's get started.

1. How to remove boiler plate code of  Parcelable interface?

Let's consider this class with Parcelable Interface implementation. This class contains overriden methods which are boiler plate at larger extends

class User(val id: String, val name: String, val age: Long, val address: String, val isPrime: Boolean, val contact: String) : Parcelable {
    constructor(parcel: Parcel) : this(
            parcel.readString(),
            parcel.readString(),
            parcel.readLong(),
            parcel.readString(),
            parcel.readByte() != 0.toByte(),
            parcel.readString())

    override fun writeToParcel(parcel: Parcel, flags: Int) {
        parcel.writeString(id)
        parcel.writeString(name)
        parcel.writeLong(age)
        parcel.writeString(address)
        parcel.writeByte(if (isPrime) 1 else 0)
        parcel.writeString(contact)
    }

    override fun describeContents(): Int = 0

    companion object CREATOR : Parcelable.Creator {
        override fun createFromParcel(parcel: Parcel): User {
            return User(parcel)
        }

        override fun newArray(size: Int): Array {
            return arrayOfNulls(size)
        }
    }

}

So here comes @Parcelize annotation into picture. Lets modify our User class using @Parcelize

@Parcelize
class User(val id: String, val name: String, val age: Long, val address: String, 
           val isPrime: Boolean, val contact: String) : Parcelable

@Parcelize is the part of androidExtensions we have to enable it by adding below snippets within module's build.gradle section.

android {
    ...
    androidExtensions {
        experimental true
    }
    ...
}

2. Using Plurals

Although plurals where introduced long time back, but have seen developers adding logics for plural strings. Let's take an example of adding plural, when any post is liked.

    <plurals> name="like_count">
        <item quantity="one">%d second ago</item>
        <item quantity="other">%d seconds ago</item>
    </plurals>

Access within the code

mContext.resources.getQuantityString(R.plurals.like_count, 1, 2)

#Output:
2 second ago

#Note: First argument matches the plural and second is the argument for %d 

3. How to Change Default layout of activity?

Its interesting because it will help to add some constant template(toolbar in all the activity etc ) which we normally add after the activity is created, henceforth saving time. Simply Go to File -> New -> Edit File Templates

Edit Templates

Changing Root Tag for layouts

In the above example we can simply replace  ROOT_TAG with <LinearLayout> and next time when we create new layout it will start with <LinearLayout>



Bingo we're done.

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Things every android developer should know - part 4

Description: In this post, I will show you some interesting tools from Android Studio that developers use.

Also check out Part 1,Part 2  and  Part 3.


So let's get started.

1. Layout Inspector: Layout Inspector is an interesting tool to help track view and their respective properties. It contains-

•    View Tree - contains the hierarchy of the Android widgets displaying the full nesting of views.
•    Properties Table - contains the properties attached to the respective view. e.g.: layouts/methods/padding and many more.

 a) How to enable it?

        Goto Tools -> Android -> Layout Inspector fig.1 

     

fig.1 Layout Inspector

 Note: Make sure you have an Android process running for your app and you have an active window present to take the screenshot.

 b) How to understand it?(fig.2)

    Left
       - 'View Tree' showing the full hierarchy of the screen.
   Center
     - Screenshot of the active window       
   Right
      - 'Properties Table' for each view.

  View Click
    - Properties of the widgets get updated on the right pane i.e. 'Properties Table.' and get highlighted on the screenshot screen.

fig.2 Layout Inspector

fig.3 Layout Inspector with Properties

RecyclerView:

<RelativeLayout 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:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:paddingBottom="@dimen/activity_vertical_margin"
    tools:context=".MainActivity">
    <android.support.v7.widget.RecyclerView
        android:id="@+id/percentList"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        />
</RelativeLayout>

RecyclerView Item:

<android.support.percent.PercentRelativeLayout
   xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
    <TextView
        android:id="@+id/fifty_huntv"
        android:background="#ff7acfff"
        android:text="20% - 50%"
        android:textColor="@android:color/white"
        style="@style/STYLE_PERCENT_TV"
        app:layout_heightPercent="20%"
        app:layout_widthPercent="50%" />
    <TextView
        android:layout_toRightOf="@id/fifty_huntv"
        android:background="#ffff5566"
        android:text="80%-50%"
        style="@style/STYLE_PERCENT_TV"
        app:layout_heightPercent="80%"
        app:layout_widthPercent="50%" />


</android.support.percent.PercentRelativeLayout>

Its an amazing tool to analyse the screen UI for the developers with all the information available on single click. Simply great.

2. How to change the DPI of the Phone using ADB?

Many times in our development phase we want to check the look of Android UI on low/high-end devices. Changing the DPI could come in handy in such cases.

So let get started.

Step 1: Find out your phone's dpi using the below command of adb shell. Search for 'mBaseDisplayInfo='. And then search for density within it. Save it for the future to revert our DPI

adb shell dumpsys display

Step 2: Search for 'mBaseDisplayInfo' and 'density' as shown in fig.4

fig.4 Display Density

Step 3: Finally enter below adb command to change the dpi. (fig.5) with 200dpi,420dpi and 600dpi respectively

adb shell wm density 150

 


Note: If the changes do not reflect you can also try:

adb shell wm density 150 && adb reboot

That it, the screen will be reloaded and icon sizes will change to withstand the density specified in the command.

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Things every android developer should know - part 3

Description: In this post I'm gonna demonstrate some useful tips which we could come handy in our app development life cycle

Also check out Part 1 and Part 2.

So let 's get started.

1. Grant all permissions at once in Marshmallow and above.  

GIST Snippet Here

As we know marshmallow compatible apps require permissions. So we normally show permission dialog to the user asking to grant us. That's fine. But every time clicking that 'allow' feels annoying for developers.

So the idea is to allow all the permissions at once without every time clicking the allow button.

Below  shell script will help to make it happen flawlessly.

#!/bin/sh

#add your package_name
PACKAGE=com.app.code2concept

#create array with all the permission you need to enabled    
PKG_ARRAY='android.permission.CALL_PHONE
        android.permission.GET_ACCOUNTS
        android.permission.READ_SMS
        android.permission.READ_CONTACTS
        android.permission.ACCESS_FINE_LOCATION
        android.permission.CAMERA
        android.permission.WRITE_EXTERNAL_STORAGE'

#lets exceute our command
for permissions in $PKG_ARRAY; 
do
 echo $permissions + ' granted'
 adb shell pm grant $PACKAGE $permissions
done

echo 'Bingo its done'

OUTPUT:

$ sh grant_all_permissions.sh
android.permission.CALL_PHONE +  granted
android.permission.GET_ACCOUNTS +  granted
android.permission.READ_SMS +  granted
android.permission.READ_CONTACTS +  granted
android.permission.ACCESS_FINE_LOCATION +  granted
android.permission.CAMERA +  granted
android.permission.WRITE_EXTERNAL_STORAGE +  granted
Bingo its done'

Before


After

2. Battery Historian

Battery historian translate the battery stats into visualization form thereby helping us to figure out whats the cause and how we can optimized our battery usage.

Pre-requisite:
1. 'adb' is configured
2. Devices is detectable using 'adb devices' command
3. Python(2.7)  is install and path is set.

Step 1: Reset the battery stats to fetch fresh info using below

adb shell dumpsys batterystats --reset

Note: Disconnect phone and explore the app for few minutes and connect again

Step 2: Capture 'batterystats' using below command

adb shell dumpsys batterystats > batterystats.txt

Note: The command creates a file name 'batterystats.txt' into the current directory

Step 3: Clone or download the Github repo of 'Battery Historian' from Here. You will find a python script at path '../battery-historian/scripts/historian.py'

Note: You can keep both 'historian.py' and 'batterystats.txt' in the same folder for ease

Step 4: Finally let execute the python script against our 'batterstats.txt' as input as show below

python historian.py batterystats.txt > batterystats.html

This will create 'battertstats.html' fig.1 which we can use to analyse the battery usage as shown HERE.

fig.1

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