Eclipse Window Builder Monty hall gui

Question

My program is set to test the Monty Hall problem 10000 times and then set text boxes to the number of rounds (10000) and the number of wins, only it doesnt take the second text box and set the text when the method is called, can anyone tell me why?

 package com.main.www;

import java.awt.EventQueue;
import java.util.Random;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JTextField;

public class MontyHallRedo {
public static final Random gen = new Random();
public static final int ROUNDS = 10000;

/** chooses a random door other than door1 or door2 */
private static int chooseAnotherDoor(int door1, int door2) {
    int result;
    do
        result = gen.nextInt(3);
    while (result == door1 || result == door2);
    return result;
}

private JFrame frame;
private JTextField textField;

/**
 * Launch the application.
 */
public static void main(String[] args) {
    EventQueue.invokeLater(new Runnable() {
        public void run() {
            try {
                MontyHallRedo window = new MontyHallRedo();
                window.frame.setVisible(true);
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    });
    calculate();
}

String ROUNDS2 = String.valueOf(ROUNDS);

private JLabel lblRoundsWon;
private static JTextField textField_1;

/**
 * Create the application.
 */
public MontyHallRedo() {
    initialize();
}

/**
 * Initialize the contents of the frame.
 */
private void initialize() {

    calculate();

    frame = new JFrame();
    frame.setBounds(100, 100, 716, 507);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.getContentPane().setLayout(null);

    JLabel lblRounds = new JLabel("Rounds Played:");
    lblRounds.setBounds(10, 155, 98, 49);
    frame.getContentPane().add(lblRounds);

    textField = new JTextField();
    textField.setBounds(94, 169, 86, 20);
    frame.getContentPane().add(textField);
    textField.setColumns(10);
    textField.setText(ROUNDS2);
    textField.setEditable(false);

    lblRoundsWon = new JLabel("Rounds Won:");
    lblRoundsWon.setBounds(237, 155, 68, 49);
    frame.getContentPane().add(lblRoundsWon);

    textField_1 = new JTextField();
    textField_1.setBounds(315, 169, 86, 20);
    frame.getContentPane().add(textField_1);
    textField_1.setColumns(10);
    textField_1.setEditable(false);

}

private static void calculate() {
    int wins = 0;
    for (int i = 0; i < ROUNDS; i++) {
        int prize = gen.nextInt(3);
        int userChoice1 = gen.nextInt(3);
        // host opens door other than user's choice without prize
        int hostChoice = chooseAnotherDoor(prize, userChoice1);
        // user always switches
        int userChoice2 = chooseAnotherDoor(userChoice1, hostChoice);
        if (userChoice2 == prize)
            wins++;
        textField_1.setText(String.format("%.4f", wins));
    }
}
}

Answer 1

calculate() is getting called in initialize() before the GUI objects are created.

textField_1.setText(String.format("%.4f", wins));

when above line is called, textField_1 is not a valid object.