java - Eclipse Window Builder Monty hall gui -

my program set test monty hall problem 10000 times , set text boxes number of rounds (10000) , number of wins, doesnt take second text box , set text when method called, can 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 random door other door1 or door2 */ private static int chooseanotherdoor(int door1, int door2) {     int result;             result = gen.nextint(3);     while (result == door1 || result == door2);     return result; }  private jframe frame; private jtextfield textfield;  /**  * launch 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 application.  */ public montyhallredo() {     initialize(); }  /**  * initialize contents of 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;     (int = 0; < rounds; i++) {         int prize = gen.nextint(3);         int userchoice1 = gen.nextint(3);         // host opens door other user's choice without prize         int hostchoice = chooseanotherdoor(prize, userchoice1);         // user switches         int userchoice2 = chooseanotherdoor(userchoice1, hostchoice);         if (userchoice2 == prize)             wins++;         textfield_1.settext(string.format("%.4f", wins));     } } } 

calculate() getting called in initialize() before gui objects created.

textfield_1.settext(string.format("%.4f", wins)); 

when above line called, textfield_1 not valid object.