Question

I am currently having the problem of not able to run the following code in Android app development.

import java.util.ArrayList;

public class Test extends FragmentActivity {

ArrayList<String> random;

@Override
protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);
        for (int a=0; a<11; a++){
        random.add("a");
    }
            }
    }

I know the above code does useless action but that is simplified from my problem in the for loop code in JAVA. And I got this error from the error log, “unhandled event loop exception”. Can anyone point out that what I am doing wrong please?

Answer 1

There are at least two problems (I suspect).

First, you’re getting a NullPointerException because you’re not initializing random with a value referring to an actual object.

Next, your syntax is bad here:

for (int a=0; a<11; a++);

Your code is only adding a single element to random – it’s equivalent to:

for (int a=0; a<11; a++)
{
}
random.add("a");

I very much doubt that that’s what you were intending. My guess is that you wanted this instead:

for (int a=0; a<11; a++)
{
    random.add("a");
}