Question: I am creating a applet in java where the user enters some data into four different four different text fields, clicks a button, and the data is taken from those fields and stored in a text field next to it. 

I have a button made, and it implements ActionListener, just not sure how to get the text from the four fields into the one field together.

Answer: 
No, it's defined. 

`nodeptr p = start, n;` defined 2 variables, `p` and `n`. And `p` is initialized by `start`, while `n` is not.
It is perfectly legal declare multiple variables in a single line of code. However note that in you example both start and n will be of type nodeptr. However you cannot have something like this:
int a, float b, double c; //this is illegal