Question

based on the contents of a vector(IDs), i m trying to create the corresponding no. of buttons but I m having problems doing that. I was wondering if anyone could help?

Below is the code that i m using to try to get that done...

ButtonField[] btn = new ButtonField[list.IDs.size()];
        for(int i=0; i<list.IDs.size(); i++){
            btn[i].setLabel((String)list.IDs.elementAt(i));
            add(btn[i]);
        }

I m currently getting an null pointer exception on the setLabel line.

Answer 1

You are creating an array (btn) of ButtonFields but you aren t actually initializing the actual elements of the array.

When you create an array in Java, all of the elements of the array are initially NULL.

Try this:

ButtonField[] btn = new ButtonField[list.IDs.size()];
        for(int i=0; i<list.IDs.size(); i++){
            btn[i] = new ButtonField(...);
            btn[i].setLabel((String)list.IDs.elementAt(i));
            add(btn[i]);
        }

Notice the new line, which sets the array element to an actual object:

btn[i] = new ButtonField(...);

Of course, you will need to fill in whatever arguments are necessary for the constructor.

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