java - Writer not writing anything to file -

public class adddetails extends application {     private final string filename = "c:\\users\\marsh\\onedrive\\documents\\customprograms\\calcprob\\players.txt";     private string name;     private char hand1, hand1;     private double skill1, skill2;     file file = new file(filename);     fileoutputstream fos = null;     writer writer = null;     static stage classstage = new stage();     string x = null;      public adddetails() {         name = "";         hand = '\0';         skill = 0.0;         bhand = '\0';         bskill = 0.0;     }      @suppresswarnings("restriction")     @override     public void start(stage mystage) throws ioexception {         classstage = mystage;         mystage.settitle("details");          gridpane rootnode = new gridpane();         rootnode.setpadding(new insets(15));         rootnode.sethgap(5);         rootnode.setvgap(5);         rootnode.setalignment(pos.center);          scene myscene = new scene(rootnode, 300, 200);          rootnode.add(new label("name:"), 0, 0);         textfield name = new textfield();         rootnode.add(name, 1, 0);         rootnode.add(new label("hand:"), 0, 1);         textfield hand = new textfield();         rootnode.add(hand, 1, 1);         rootnode.add(new label("skill:"), 0, 2);         textfield skill = new textfield();         rootnode.add(skill, 1, 2);         rootnode.add(new label("skill:"), 0, 3);         textfield bskill = new textfield();         rootnode.add(bskill, 1, 3);         rootnode.add(new label("hand:"), 0, 4);         textfield bhand = new textfield();         rootnode.add(bhand, 1, 4);         button sbutton = new button("store");         rootnode.add(sbutton, 1, 5);         gridpane.sethalignment(sbutton, hpos.left);         button ebutton = new button("finish");         rootnode.add(ebutton, 1, 5);         gridpane.sethalignment(ebutton, hpos.right);         name.setprompttext("enter name");         hand.setprompttext("enter hand );             skill.setprompttext("enter skill");         bhand.setprompttext("enter hand");         bskill.setprompttext("enter skill");          mystage.setscene(myscene);         mystage.show();          try {             bufferedreader in = new bufferedreader(new inputstreamreader(new fileinputstream(file), "utf-8"));             fos = new fileoutputstream(file, true);             writer = new outputstreamwriter(fos, "utf-8");              ebutton.setonaction(e -> {                 mystage.close();                 try {                     writer.close();                 } catch (ioexception writerclose) {                     alert alert = new alert(alerttype.error);                     alert.settitle("error");                     alert.setheadertext("error encountered");                     alert.setcontenttext("error: " + writerclose.getmessage());                 }             });              sbutton.setonaction(e -> {                 name = name.gettext();                 hand = hand.gettext().charat(0);                 skill = double.valueof(skill.gettext());                 bskill = double.valueof(bskill.gettext());                 bhand = bhand.gettext().charat(0);                 hand = character.touppercase(hand);                 bhand = character.touppercase(bhand);                  system.out.println(name + "\t" + hand + "\t" + skill + "\t" + bhand + "\t" + bskill);                  try {                      writer.write(name + "\t" + hand + "\t" + skill + "\t" + bhand + "\t" + bskill);                      name.clear();                     hand.clear();                     skill.clear();                     bskill.clear();                     bhand.clear();                  } catch (ioexception br) {                      alert alert = new alert(alerttype.error);                     alert.settitle("error");                     alert.setheadertext("error encountered");                     alert.setcontenttext("error: " + br.getmessage());                  }             });         } catch (ioexception e) {             alert alert = new alert(alerttype.error);             alert.settitle("error");             alert.setheadertext("error encountered");             alert.setcontenttext("error: " + e.getmessage());         } {             try {                 if (writer != null)                     writer.close();                 if (fos != null)                     fos.close();             } catch (ioexception finalclose) {                 alert alert = new alert(alerttype.error);                 alert.settitle("error");                 alert.setheadertext("error encountered");                 alert.setcontenttext("error: " + finalclose.getmessage());             }         }     }      public static void main(string[] args) {         launch(args);     } } 

you're closing output file after it's opened, without writing anything.

the open , close run in main thread when start called, while attempted write happens in event thread when sbutton clicked.

a simple fix open , close fos in sbutton action listener doing write.