Plane assignment program from hell for a very bad java programmer

Problem:
-Create a java program in which an airline can keep track of it's seating assignments.

-Using the InputDialog Method ask the user how many people will be coming aboard the plane.

- The plane consists of only 5 seats.

- Keep assigning people to the seats in the plane until all seats are filled.

-Once every seat is filled tell the user no more seats are avaiable.


Question:
Ok I have a simple question. How do I make it so that I can read the elements inside an array and if any one of them gets to or above 5 it stops letting me input numbers. For example, let's say I have 2 in index 0 and 3 in index 1, that makes 5 so I don't want to store anything more and when i go and input another number it doesn't let me. Another example, let's say index 0 holds the number 5 then it won't let me progress to index 1 because I already have the desired number which is 5. I hope that was pretty clear. This is for a plane assignment seating program with only 5 seats. This is what I have so far:

import javax.swing.JOptionPane;


public class Seating {
    public static void main(String args[]) {
    	 int seatstaken = 0;
    	 int seats[] = new int [5];
    do{	 
    JOptionPane.showMessageDialog(null, "Welcome to Coqui Air!");
    	
    
    
    for ( int i= 0; i < seats.length; i ++){
    	 String party = JOptionPane.showInputDialog("How many people will be traveling with you today?");
    	 int partynum = Integer.parseInt(party);
    	 seats[i] = partynum;
    	
    }
    
    for (int i = 0; i <seats.length; i++){
    	seatstaken += seats[i];
    }
    
    }while(seatstaken < seats.length);
    
    if (seatstaken > 5){
    	 JOptionPane.showMessageDialog(null, "Plane full.");
    }
    	
    
    	 
    
    	
}
    
}

It's pretty terrible code, but I'm a beggining java programmer and my proffessor did not explain this subject of arrays at all, he just gave us a very brief example and it did not clear up my doubts whatsoever. Also in his example he uses a scanner for input, the problem requires that we use the JOptionPane user input method. Any help is appreciated as I have been trying to solve this since 4 pm my time.