java - How to set Combobox value to one of the choices in the list -

i need change value of current jcombobox value.

i got in settings gui class used main.class:

package com.tominocz.cookieclicker;  import java.awt.borderlayout; import java.awt.color; import java.awt.dimension; import java.awt.flowlayout; import java.awt.toolkit; import java.awt.event.actionevent; import java.awt.event.actionlistener;  import javax.swing.imageicon; import javax.swing.jbutton; import javax.swing.jcombobox; import javax.swing.jframe; import javax.swing.jpanel; import javax.swing.border.lineborder;  @suppresswarnings({ "serial", "rawtypes", "unchecked" }) public class settings extends jframe {      private string[] choicelist = { "default (arial)", "comic sans ms" };      public class choicecombolistener implements actionlistener {         public void actionperformed(actionevent ev) {             jcombobox cb = (jcombobox) ev.getsource();             string currentcomboselection = (string) cb.getselecteditem();             if (currentcomboselection.equals(choicelist[0])) {                 main.selectedfont = "arial";                 main.refreshgame();                 main.opt.setsize(240, 105);                 save.savegame(main.save);             }             if (currentcomboselection.equals(choicelist[1])) {                 main.selectedfont = "comic sans ms";                 main.refreshgame();                 main.opt.setsize(240, 107);                 save.savegame(main.save);             }         }     }      public settings() {         super("settings");         setlayout(new flowlayout());          dimension screen = toolkit.getdefaulttoolkit().getscreensize();         int x = (int) (((screen.getwidth()) - this.getwidth()) / 2 - 200);         int y = (int) (((screen.getheight()) - this.getheight()) / 2 - 100);         this.setlocation(x, y);         this.setalwaysontop(true);          this.seticonimage(((imageicon) main.settingsicon).getimage());          jpanel northpanel = new jpanel();         northpanel.setignorerepaint(true);         northpanel.setborder(new lineborder(color.gray));         this.getcontentpane().add(northpanel, borderlayout.north);         jcombobox choicecombo = new jcombobox(choicelist);         northpanel.add(main.choosefont);         northpanel.add(choicecombo);         choicecombo.addactionlistener(new choicecombolistener());          // hereeeeeeeeeeeeeeeeeeeeeee         if (main.selectedfont.equals("comic sans ms")) {             [the current jcombobox value(may default 1 - choicelist[0])] = choicelist[1];         }         // hereeeeeeeeeeeeeeeeeeeeeee          main.ok.setborder(null);         main.ok.setborderpainted(false);         main.ok.setcontentareafilled(false);         add(main.ok);         main.ok.addactionlistener(new actionlistener() {             public void actionperformed(actionevent e) {                 object source = e.getsource();                 if (source instanceof jbutton) {                     main.opt.dispose();                 }             }         });     } } 

now how change currentcomboselection value if i'm not available use in:

public settings() {

...

?

suggestions:

• you can set jcombobox's selected item 1 of 2 ways: via setselectedindex(int index) or setselecteditem(object item) first way, choose index of desired selection , 2nd way choose object held jcombobox (here strings) supposed selected.

other issues:

• you getting data main class directly accessing field, possibly static field @ that. don't make code tightly coupled, set hard find bugs, , difficult enhance or change. use tightly controlled getter methods instead. i.e., give main public font getselectedfont() method class can call method in non-static way without directly fiddling main's fields, without making main fields static shouldn't static.
• the same goes directly changing main's state in settings class -- that's not how java safely same reasons above. oops principles don't thrown out window because you're creating event-driven gui.
• it looks supposed secondary window displayed main gui window. if so, should displayed dialog, such jdialog or joptionpane , not jframe. prevent display icon on os's toolbar, guarantee window on top of main window, , allow window displayed in modal fashion if need be.
• you're setting layout of contentpane flowlayout, , yet trying add jpanel borderlayout.north position. won't work.

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for example, simple code similar yours uses joptionpane secondary dialog window:

import java.awt.component; import java.awt.dimension; import java.awt.event.actionevent; import javax.swing.*;  public class testsettingspanel {     private static void createandshowgui() {       mainpanel mainpanel = new mainpanel();        jframe frame = new jframe("test settings");       frame.setdefaultcloseoperation(jframe.dispose_on_close);       frame.getcontentpane().add(mainpanel);       frame.pack();       frame.setlocationbyplatform(true);       frame.setvisible(true);    }     public static void main(string[] args) {       swingutilities.invokelater(new runnable() {          public void run() {             createandshowgui();          }       });    } }  class mainpanel extends jpanel {    private static final long serialversionuid = 1l;    public static final string[] choice_list = { "default (arial)",          "comic sans ms", "courier", "times new roman" };    private static final int pref_w = 500;    private static final int pref_h = 400;    private jtextfield fontfield = new jtextfield(10);    private settingspanel settingspanel;     public mainpanel() {       fontfield.setfocusable(false);       fontfield.settext(choice_list[0]);        add(new jlabel("font: "));       add(fontfield);       add(new jbutton(new settingsaction("change settings")));    }     @override // let's make bigger    public dimension getpreferredsize() {       if (ispreferredsizeset()) {          return super.getpreferredsize();       }       return new dimension(pref_w, pref_h);    }     private class settingsaction extends abstractaction {       private static final long serialversionuid = 1l;        public settingsaction(string name) {          // give our button / action text          super(name);          int mnemonic = (int) name.charat(0);          putvalue(mnemonic_key, mnemonic); // set alt-key combination short-cut       }        @override       public void actionperformed(actionevent e) {          // create our settingspanel in lazy fashion          if (settingspanel == null) {             settingspanel = new settingspanel();          }           // set combo selection calling setsetting method:          settingspanel.setsetting(fontfield.gettext());           // create joptionpane , dsiplay settingspanle inside of          component parentcomponent = mainpanel.this;          string title = "change font settings";          int optiontype = joptionpane.ok_cancel_option;          int messagetype = joptionpane.plain_message;          // display joptionpane here          int result = joptionpane.showconfirmdialog(parentcomponent,                settingspanel, title, optiontype, messagetype);          // find out button user pressed          if (result == joptionpane.ok_option) {             // if ok button pressed, extract information settingspanel             string fonttype = settingspanel.getfonttype();             fontfield.settext(fonttype);          }       }    } }  // note settingspanel ignorant gui displays it.  class settingspanel extends jpanel {    private static final long serialversionuid = 1l;    private jcombobox<string> choicelistcombo = new jcombobox<>(mainpanel.choice_list);     public settingspanel() {       add(new jlabel("select font:"));       add(choicelistcombo);    }     // allow outside classes set combo's selected item     public void setsetting(string text) {       if (text != null && !text.trim().isempty()) {          choicelistcombo.setselecteditem(text);       }    }     // allow outside classes extract selected item combo    public string getfonttype() {       return (string) choicelistcombo.getselecteditem();    }  }