Question: in my android application there is group of buttons.i have given them id as b1,b2,b3...
and using random function i'm generating a number and by using that number i'm changing button image.
ex. if random number is 6.then i want to change image of button whose id is b6.
how can i create id b6 using integer 6 and b and perform operations on that button.

```
    String id;
    Random rand=new Random();
int num=rand.nextInt(9)+1;
id="b"+num;

```

but in android id of button is not in string format

Answer: 
You can simply declare an array with all the button IDs like that:

```
int[] buttonIds = new int[] {R.b1, R.b2, ...};

```

and use it to access the ID of a random button:

```
num = rand.nextInt(buttonIds.length);
int buttonId = buttonIds[num];
findViewById(buttonId).doSomething();

```

But it'll be tedious if the number of buttons becomes large or isn't constant. But for small numbers that seems fast and simple.
The Resources class has this method:

```
public int getIdentifier (String name, String defType, String defPackage) 

```

Have a look at it.