Question

I have defined the TextView array as final.
And I set a OnClickListener() for all the array elements,
and I am able to use setBackground (even the array is not set as final).
But I cannot use getText() method which return NullPointerException during operation.

Do you guys know why is the problem existed?

final ArrayList<TextView> seats = new ArrayList<TextView>();

@Override
public void onCreate(Bundle savedInstanceState) {
    .
    .
    seats.add((TextView) findViewById(R.id.A1));
    seats.add((TextView) findViewById(R.id.A2));
    seats.add((TextView) findViewById(R.id.A3));
    .
    .
    for (int i = 0; i<seats.size(); i++)
        seats.get(i).setOnClickListener(seatClick);
    .
    .
}
OnClickListener seatClick = new OnClickListener()
{
    @Override
    public void onClick(View v)
    {
        v.setBackgroundColor(-16711681);
        Toast.makeText(getApplicationContext(), ((TextView)v).getText().toString(), Toast.LENGTH_SHORT);
    }
};

The TextView is defined something like this:

<TextView
        android:id="@+id/A1"
        android:background="#0AFC1A"
        android:textColor="#FFFFFF"
        android:layout_width="30dp"
        android:layout_height="30dp"
        android:gravity="center"
        android:text="A1" />

Answer 1

i tested your code its working fine. just change it.

 Toast.makeText(getApplicationContext(), ((TextView)v).getText().toString(), Toast.LENGTH_SHORT).show();

this is full code

seats.add((TextView) findViewById(R.id.textView2));
            seats.add((TextView) findViewById(R.id.textView3));
            seats.add((TextView) findViewById(R.id.textView4));



            OnClickListener seatClick = new OnClickListener()
            {
                @Override
                public void onClick(View v)
                {
                  v.setBackgroundColor(-16711681);
                      Toast.makeText(getApplicationContext(), ((TextView)v).getText().toString(), Toast.LENGTH_SHORT).show();
                }
            };

            for (int i = 0; i<seats.size(); i++)
                seats.get(i).setOnClickListener(seatClick);