How i can optimize this code that contain some repetitive line?

Question

I have below code in android programming ``` Button btn1 = ( Button ) findViewById( R.id.btn1 ); Button btn2 = ( Button ) findViewById( R.id.btn2 ); Button btn3 = ( Button ) findViewById( R.id.btn3 ); Button btn4 = ( Button ) findViewById( R.id.btn4 ); Button btn5 = ( Button ) findViewById( R.id.btn5 ); Button btn6 = ( Button ) findViewById( R.id.btn6 ); Button btn7 = ( Button ) findViewById( R.id.btn7 ); Button btn8 = ( Button ) findViewById( R.id.btn8 ); Button btn9 = ( Button ) findViewById( R.id.btn9 ); ``` And it continue untill btn30 In python I optimize it by below easy code ``` #is a python syntax (for_statement) #python work by tab for i in range(1,31): #in python not need to declare temp temp="""Button btn"""+str(i)+"""=(Button)findViewById(R.id.btn"""+str(i)+""")""" exec(temp)#a default function in python ``` In java programing how i can do it?Or can I do it?do exist a easy code for it? `UPDATE 1` SO there are two way to do it `Code 1`: ``` final int number = 30; final Butt…

Accepted Answer

You can create an array of `Button`'s and use `getIdentifier` method that allows you to get an identifier by its name.

```
final int number = 30;
final Button[] buttons = new Button[number];
final Resources resources = getResources();

for (int i = 0; i < number; i++) {
    final String name = "btn" + (i + 1);
    final int id = resources.getIdentifier(name, "id", getPackageName());

buttons[i] = (Button) findViewById(id);
}
```

In case someone is interested how to achive the same result using Java only

The solution above uses `Android` specific methods (such as `getResources`, `getIdentifier`) and can not be used in usual `Java`, but we can use a `reflection` and write a method that works like a `getIdentifier`:

```
public static int getIdByName(final String name) {
    try {
        final Field field = R.id.class.getDeclaredField(name);

field.setAccessible(true);
        return field.getInt(null);
    } catch (Exception ignore) {
        return -1;
    }
}
```

And then:

```
final Button[] buttons = new Button[30];

for (int i = 0; i < buttons.length; i++) {
    buttons[i] = (Button) findViewById(getIdByName("btn" + (i + 1)));
}
```

How i can optimize this code that contain some repetitive line?

Solution

Problem