It feels like we’ve been using android devices for ages now, but it has only been a little over ten years since the android debut.

• Origin story: In October 2003, before the term “smartphone” was used and much before IOS launched its first iPhone, Android Inc was founded in California. One of the founders, Rubin, quoted that Android Inc was going to develop smarter mobile devices that are more aware of its owner’s location and preferences.
  As reported by PC World, Android OS was originally meant to improve the OS of digital cameras. The company even pitched to investors in 2004, explaining how Android could be installed on a camera and connected to a PC. After the market for stand-alone cameras declined, the company shifted its gears to OS inside mobile devices.
• Widely popular: Android vs. iOS development has been dominating the operating system market for the past few years. Android holds 68% of the market share, and iOS holds about 29.92% while the rest are smaller operating systems.
• Built using different programming languages: Java is the most-used language to build an android app. Some other languages are Kotlin, C++, C#, and Python.
• Other trivia: Android released its first version of OS in Sept. 2008 with no code name at all. A few months later, Android 1.1 was released. It didn’t have a public code name, but it was internally referred to as “Petit four,” which refers to a French dessert.
  
  It was not until the launch of Android 1.5 that the OS version got its first public code name: “Cupcake.” The credit for naming the Android versions after candy and desserts have gone to its project manager, Ryan Gibson. When asked the reason behind these names, he said, “Since these devices make our lives so sweet, each Android version is named after a dessert.”
  Another fun fact, the android robot itself is an open-source project. Unlike other companies, Android didn’t protect the mascot allowing it to be modified and redesigned under the Creative Commons 3.0 Attribution License.
  In July 2005, Google acquired Android Inc. with its core employees Rubin, Miner, and White. And, every year when Google reveals its code name, it places a new statue with the code name on the lawn in front of its company office in California.

A lot of features make Android a great choice vs. other operating systems. Two of which are:

• Android devices span all price ranges.
• More smartphone manufacturers use Android.

These are some of the tools that are commonly used by Android developers:

1. Android Studio

This is the official IDE for Android development. The tool provides a common environment in which developers can build apps for various Android platforms such as phones, tablets, TVs, etc.

2. Android NDK

Using the Android Native Development Kit, Android developers can develop parts of the app using native code, written in C and C++. It also libraries through which native activities and certain physical components can be accessed.

3. Android Debug Bridge or ADB

As the name suggests, this tool is used for debugging Android devices. The tool is a command-line interface tool that lets you communicate with a device and perform various functions like installing, copying files, and running commands through the Unix shell.

4. Genymotion

Genymotion is an Android Emulator that allows Android developers to interact with a virtual Android environment. It allows users to test how the app would work on a wide range of devices.

5. Instabug

This tool enables Android developers to check for bugs, and crashes and also acquire feedback from users so that these bugs can be worked upon. Instabug would have to be added to the live app so that the end-users can reach developers via it.

Below are some key points that we at Flexiple have learned through trial and error - a process of filtering through over 15,000 developers. You can use these in your process to hire Android developers.

• Years of software development experience: Be specific about the technology you’re looking for and the number of years of experience needed. A proxy to years of experience can be the number of production-level apps worked on.
• Expertise in a specific programming language: Different programming languages used to develop an android app have its own nuances. While a good programmer can pick up other languages, it’s a plus point to hire a developer who already has expertise in it.
• Type of products built in the past: Based on the type of product you are trying to build - social network, SAAS product, etc. - you can prioritize certain developers over others.
• Exposure to specific industries: Developers who have built products in certain industries will already know key aspects of laying the foundation for a great product and will be able to predict possible problems.
• Experience working remotely: A developer with past remote work experience is an added advantage as they would have first-hand experience of everything - right from how contracts work to streamlined communication, as well as timelines and deliverables.
• Strong communication: An essential thing to look at when hiring a freelancer is excellent communication skills. Since all the interaction happens online, a freelancer should be able to effectively communicate to ensure a streamlined execution of all work.

If you'd like to see detailed mobile developer job descriptions, check out these templates for Flutter and Android JDs.

Now that you have made a quality JD, it can still be tricky to evaluate the skills of your applicants when you hire Android developers. To help you with that, we have created a pool of questions that a good Android developer should be comfortable with.

It is important to note that the ability to answer these questions doesn't imply that you have a top quality candidate. But it definitely is a big step in that direction.

To help you navigate through these questions, we’ve categorized the interview questions in 3 parts:

A. Basic concepts: Includes all basic concepts used across languages but we've focused on their significance in Android. This will give you an understanding of how strong their programming foundation is.

B. Advanced concepts: Includes all concepts that someone with higher expertise should know.

C. DS/Algorithm questions: To test the logical capability of the candidate.

A. Basic concepts

Coming soon!

B. Advanced concepts

Coming soon!

C. Data Structure/ Algorithm

1. Given a string containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid. An input string is valid if: Open brackets must be closed by the same type of brackets. Open brackets must be closed in the correct order. Note that an empty string is also considered valid.

class ValidParenthesesFunc {
    func isValid(_ s: String) -> Bool {
        var stc = [Character]()

        for char in s {
            if char == "(" || char == "[" || char == "{" {
                stc.append(char)
            } else if char == ")" {
                guard stc.count != 0 && stc.removeLast() == "(" else {
                    return false
                }
            } else if char == "]" {
                guard stc.count != 0 && stc.removeLast() == "[" else {
                    return false
                }
            } else if char == "}" {
                guard stc.count != 0 && stc.removeLast() == "{" else {
                    return false
                }
            }
        }
        return stc.isEmpty
    }
}

The above code will input 0(false). 

2. Write a Java Program to find whether a string or number is palindrome or not.

import java.util.Scanner;
public class Palindrome {
    public static void main (String[] args) {
        String original, reverse = "";
 Scanner in = new Scanner(System.in);
       int length;
        System.out.println("Enter a number or a string");
        original = in.nextLine();
        length = original.length();
        for (int i =length -1; i>;=0; i--) {
            reverse = reverse + original.charAt(i);
        }
        System.out.println("The reverse is: " +reverse);

        if(original.equals(reverse))
            System.out.println("The string is a palindrome");
        else
            System.out.println("The stringis not a palindrome");

    }
}

Output:
For String- Enter a number or a string
sam
The reverse is: mas
The string is not a palindrome

For Number-Enter a number or a string
99
The reverse is: 99
The number is a palindrome 

3. What will the output of the following code be?

class Test {
public static void main(String args[])
    {
        String str1 = new String("Hello World");
        String str2 = new String("Hello World");

        String str3 = "Hello World";
        String str4 = "Hello World";

        int a = 0, b = 0, c = 0;

        if (str3 == str4)
            a = 1;
        else
            a = 2;

        if (str1.equals(str3))
            b = 1;
        else
            b = 2;

        if (str1 == str4)
            c = 1;
        else
            c = 2;
        System.out.println("a= " + a + " b= " + b + " c= " + c);
    }
}

A. a=2 b=1 c=2
B. a=2 b=2 c=2
C. a=1 b=2 c=1
D. a=1 b=1 c=2

D. a=1 b=1 c=2 because a new memory is created when we make an object with the help of the ‘new’ keyword, 
and the reference variable contains the memory location. 
Here the memory is created with the same string twice, but since we are comparing objects and not strings, 
the object will point to a different memory location and so they are not equal. 

That in a nutshell, is everything you need to consider when hiring a freelance Android developer. As discussed, it isn't easy to find a quality freelance android developer but this guide makes the process easier for you. To offload the entire hiring process, reach out to us at Flexiple. We've designed a high-quality, 6-step screening process to find the top 1% freelance developers. You can find the best freelance Android developers here. We've already served over a hundred clients, earning great reviews for the quality of service.

Lastly, to quickly summarize it for you:

• Note your project requirements and hire accordingly. Do not go for the lowest or the highest-paid developer.
• Don’t hire without vetting- consider asking questions right from the basics to advanced to logical questions.
• Look for companies like Flexiple that help you find the perfect fit.

That is everything you need to know if you want to hire Android developers. Happy hiring! :)