java - Moving a focus to Next JTextfield when it crosses it Jtextfieldlimit -

i'm working design license activation part. had 2 text fields in java swing.

java code:

jtextfield1.setdocument(new jtextfieldlimit(8));    jtextfield2.setdocument(new jtextfieldlimit(8)); 

when jtextfield1 ended entering 8 alphanumeric characters. had move focus next jtextfield2 automatically.are there default methods available or how can done.

the basic answer question is, keyboardfocusmanager#focusnextcompnent

the longer answer more complicated.

lets start fact java 1.4, no longer required or recommended utilise document functionality, instead use documentfilter, see implementing document filter , documentfilter examples more details

i prefer reusable , configurable solutions, end, i'd prefer see solution allowed me change decision making processes involved in deciding when focus should transferred , configure how transfer occurs

now, remember, use custom focustraversalpolicy change way in focus moves between components, isn't desirable solution.

let's start basics...

    public interface autofocustransferdelegate {         public boolean shouldtransferfocus(document doc);     }      public interface autofocustransferobserver {         public void focustransfershouldoccur(document doc);     }      public class autofocustransferhandler implements documentlistener {          private autofocustransferlistener listener;         private autofocustransferdelegate delegate;          public autofocustransferhandler(autofocustransferlistener listener, autofocustransferdelegate delegate) {             this.listener = listener;             this.delegate = delegate;         }          @override         public void insertupdate(documentevent e) {             checkfortransfer(e.getdocument());         }          @override         public void removeupdate(documentevent e) {             checkfortransfer(e.getdocument());         }          @override         public void changedupdate(documentevent e) {             checkfortransfer(e.getdocument());         }          public void checkfortransfer(document doc) {             if (delegate != null && delegate.shouldtransferfocus(doc)) {                 if (listener != null) {                     listener.focustransfershouldoccur(doc);                 }             }         }      } 

here have "delegate", used configure , customise decisions making process on when transfer should take place, "observer" notified when transfer should take place, allows decide "how" transfer should take place , documentlistener monitor document used query delegate , notify observer.

sure, wrap in single class, now, have simple , highly configurable solution don't need extend classes in order achieve new result (nit pick on part). it's basic example of composition on inheritance.

and might able use like...

import java.awt.eventqueue; import java.awt.gridbagconstraints; import java.awt.gridbaglayout; import java.awt.keyboardfocusmanager; import javax.swing.jbutton; import javax.swing.jframe; import javax.swing.jpanel; import javax.swing.jtextfield; import javax.swing.uimanager; import javax.swing.unsupportedlookandfeelexception; import javax.swing.event.documentevent; import javax.swing.event.documentlistener; import javax.swing.text.abstractdocument; import javax.swing.text.attributeset; import javax.swing.text.badlocationexception; import javax.swing.text.document; import javax.swing.text.documentfilter;  public class test {      public static void main(string[] args) {         new test();     }      public test() {         eventqueue.invokelater(new runnable() {             @override             public void run() {                 try {                     uimanager.setlookandfeel(uimanager.getsystemlookandfeelclassname());                 } catch (classnotfoundexception | instantiationexception | illegalaccessexception | unsupportedlookandfeelexception ex) {                     ex.printstacktrace();                 }                  jframe frame = new jframe("testing");                 frame.setdefaultcloseoperation(jframe.exit_on_close);                 frame.add(new testpane());                 frame.pack();                 frame.setlocationrelativeto(null);                 frame.setvisible(true);             }         });     }      public class testpane extends jpanel {          public testpane() {             setlayout(new gridbaglayout());             gridbagconstraints gbc = new gridbagconstraints();             gbc.gridwidth = gridbagconstraints.remainder;              int maxcharacters = 8;             autofocustransferlistener listener = new autofocustransferlistener() {                 @override                 public void focustransfershouldoccur(document doc) {                     keyboardfocusmanager.getcurrentkeyboardfocusmanager().focusnextcomponent();                 }             };             autofocustransferdelegate delegate = new maxlengthautofocustransferdelegate(maxcharacters);             documentfilter filter = new sizefilter(maxcharacters);             documentlistener doclistener = new autofocustransferhandler(listener, delegate);              add(createtextfield(8, filter, doclistener), gbc);             add(createtextfield(8, filter, doclistener), gbc);             add(new jbutton("ok"), gbc);         }          protected  jtextfield createtextfield(int maxcharacters, documentfilter filter, documentlistener doclistener) {             jtextfield field = new jtextfield(maxcharacters);             abstractdocument doc = (abstractdocument)field.getdocument();             doc.setdocumentfilter(filter);             doc.adddocumentlistener(doclistener);             return field;         }      }      public class maxlengthautofocustransferdelegate implements autofocustransferdelegate {          private int maxlength;          public maxlengthautofocustransferdelegate(int maxlength) {             this.maxlength = maxlength;         }          @override         public boolean shouldtransferfocus(document doc) {             return doc.getlength() >= maxlength;         }      }      public class sizefilter extends documentfilter {          private int maxcharacters;          public sizefilter(int maxchars) {             maxcharacters = maxchars;         }          public void insertstring(filterbypass fb, int offs, string str, attributeset a)                 throws badlocationexception {              if ((fb.getdocument().getlength() + str.length()) <= maxcharacters) {                 super.insertstring(fb, offs, str, a);             }         }          public void replace(filterbypass fb, int offs, int length, string str, attributeset a)                 throws badlocationexception {              if ((fb.getdocument().getlength() + str.length() - length) <= maxcharacters) {                 super.replace(fb, offs, length, str, a);             }         }     }      public class autofocustransferhandler implements documentlistener {          private autofocustransferlistener listener;         private autofocustransferdelegate delegate;          public autofocustransferhandler(autofocustransferlistener listener, autofocustransferdelegate delegate) {             this.listener = listener;             this.delegate = delegate;         }          @override         public void insertupdate(documentevent e) {             checkfortransfer(e.getdocument());         }          @override         public void removeupdate(documentevent e) {             checkfortransfer(e.getdocument());         }          @override         public void changedupdate(documentevent e) {             checkfortransfer(e.getdocument());         }          public void checkfortransfer(document doc) {             if (delegate != null && delegate.shouldtransferfocus(doc)) {                 if (listener != null) {                     listener.focustransfershouldoccur(doc);                 }             }         }      }      public interface autofocustransferdelegate {          public boolean shouldtransferfocus(document doc);     }      public interface autofocustransferlistener {          public void focustransfershouldoccur(document doc);     } }