Android For Beginners: Interview Questions And Answers.

Android for beginners: Interview Help

I) What are the components of Android? Elaborate!

The main components of Android are:

1) Activity

2) Intent

3) Service

4) Broadcast receiver

5) Content Provider

1) Activity

Activity provides an interface for users to interact with the application and take an action (for instance: Login to a website). The different screens/windows of an application are the different activities. An application generally has multiple activities.

Activities are like the pages in a website. For instance, in a Facebook app, the login screen is one activity, and the news feeds from your friends after signing in would be another one.

2) Intent

Think of Intent as a message to allow the application to request action from the other application components (like activity), for instance VIEW, CALL, PLAY etc.

Suppose, on your Facebook app, the running activity is the Newsfeed, and you want to view (in full frame) a pic your friend posted. The click action on the photo would be the View Photo Intent, and the Photo screen (which is a new activity) gets loaded on the click (as the message is communicated).

3) Services

Services are components that do not have a User Interface; they run in the background. An example of Service component in Facebook app would be the friend request notifications. They would continue to run, even if you switch to another activity or application.

4) Content Provider

Content provider is a data store that enables data sharing across different applications. Content providers provide a uniform interface to access the data. An example is Call logs.

5) Broadcast Receiver

A Broadcast receiver comes into action only in specific situations. Suppose an Intent for which a particular broadcast receiver has been registered occurs, the broadcast receiver is triggered into action and the user gets a notification for the same. (For example: Battery low notification)

You’ll get a walk-through of the entire process using examples, in Edureka’s Android for beginners training.

II) Some C programming Question for you

1) How can you print “hello world” without using semicolon (;)?

Think about it a little before looking at the solution.

Solution
This question can be solved in more than one way:
a)

 #include
  void main()
  {
  if(printf("Hello World")) { }
  }

b)

  {
  while(printf("Hello World")){}
  }

c)

 { do{} while(printf("Hello World")){} }

Sometimes, multiple choice programming questions can be asked in Android for beginners interviews. Check this one out for instance:

2) What will be output of following C code?

#include
int main()
{
int *a1;
char **a2;
float ***a3;
double ****a4;
printf("%d %d %d %d ",sizeof(a1),sizeof(a2),sizeof(a3),sizeof(a4));
return 0;
}
Options 

a) 1 2 4 8

b) 2 4 4 8

c) 2 4 2 4

d) 2 2 2 2

Answer: d.

Size of pointer is same no matter what type it is (2 byte)

Note – This is assuming that we are on a 32 bit machine. On 64 bit it will be 4 bytes.

III) Java Coding Question

1) Can you write a java code to swap two numbers?

Solution

public class Swap {
public static void main(String[ ] args)  {
int x = 5;
int y = 6;
//store 'x' in a temp variable
int temp = x;
x  =  y;
y  =  temp;
System.out.println("x=" + x+ "y=" + y);
}
}

2) Write Java code to swap two numbers without using a third variable i.e. temp in the above case.
Tough..??

Not really; in fact you know it already :)

Solution

public class Swap {
public static void main(String[ ] args)  {
int x = 5;
int y = 6;
//Add both the variables and store them in x  i.e x = 11 (x=5 + y=6).
x = x + y;
//Now subtract y from x and store in y i.e y = 5 (x=11 - y=8) . Hence initial value of x is assigned to y.
y = x - y;
//Now subtract y from x and store in x i.e x = 6 (x=11 - y=5) . Hence initial value of y is assigned to x.
x = x - y;
// Both the values are swapped successfully without using the third variable
System.out.println("x=" + x+ "y=" + y);
}
}

Candidates with advanced knowledge would be expected to answer questions much difficult than these. This post however deals with Android for beginners basics.