swing - Java documentlistener - program stop working after input -

hi have problem documentlistener. program stop working after insert value textfield. program should xor 1st row of textfields 2nd row of textfields , put result 3rd row of textfields

package opa.beta1;  import java.awt.borderlayout; import java.math.biginteger; import javax.swing.jframe; import javax.swing.jpanel; import javax.swing.jtextfield; import javax.swing.swingutilities; import javax.swing.event.documentevent; import javax.swing.event.documentlistener;  public class textfieldevent {      jtextfield arrayiv[] = new jtextfield[8];     jtextfield plaintextarray[] = new jtextfield[8];     jtextfield ciphertextarray[] = new jtextfield[8];     jframe frame = new jframe("opa");     jpanel panel1 = new jpanel();     jpanel panel2 = new jpanel();     jpanel panel3 = new jpanel();      public void setjpanel(jtextfield array[], jpanel container, string s) {         (int = 0; < 8; i++) {             array[i] = new jtextfield(s, 4);             array[i].getdocument().adddocumentlistener(new documentlistener() {                 @override                 public void insertupdate(documentevent de) {                     setciphertext();                 }                  @override                 public void removeupdate(documentevent de) {                     setciphertext();                 }                  @override                 public void changedupdate(documentevent de) {                     setciphertext();                 }             });             container.add(array[i]);         }     }      public string setxortext(jtextfield textfield1, jtextfield textfield2) {         string okno1, okno2;         okno1 = textfield1.gettext();         okno2 = textfield2.gettext();         if (okno1.equals("")) {             return okno2;         }         biginteger pom1 = new biginteger(okno1, 16);         if (okno2.equals("")) {             return okno1;         }         biginteger pom2 = new biginteger(okno2, 16);         biginteger res = pom1.xor(pom2);         string s = res.tostring(16);         return s;     }      public string setxortext(jtextfield pole1[], jtextfield pole2[], int i) {          string okno1 = pole1[i].gettext();         string okno2 = pole2[i].gettext();         if (okno1.equals("")) {             return pole2[i].gettext();         }         biginteger pom1 = new biginteger(okno1, 16);         if (okno2.equals("")) {             return pole1[i].gettext();         }         biginteger pom2 = new biginteger(okno2, 16);         biginteger res = pom1.xor(pom2);         string s = res.tostring(16);         return s;     }      public void setciphertext() {         //textfield3.settext(setxortext(textfield1, textfield2));         (int = 0; < 8; i++) {             ciphertextarray[i].settext(setxortext(arrayiv, plaintextarray, i));         }     }      public textfieldevent() {         setjpanel(arrayiv, panel1, "1a");         setjpanel(plaintextarray, panel2, "1b");         setjpanel(ciphertextarray, panel3, "1");          frame.add(panel1, borderlayout.north);         frame.add(panel2, borderlayout.center);         frame.add(panel3, borderlayout.south);          frame.setdefaultcloseoperation(jframe.dispose_on_close);         frame.pack();         frame.setvisible(true);         frame.setsize(675, 275);         frame.setresizable(false);     }      public static void main(string[] args) {         swingutilities.invokelater(new runnable() {             @override             public void run() {                 new textfieldevent();             }         });      } } 

stacktrace

exception in thread "awt-eventqueue-0" java.lang.illegalstateexception: attempt mutate in notification @ javax.swing.text.abstractdocument.writelock(abstractdocument.java:1338) @ javax.swing.text.abstractdocument.replace(abstractdocument.java:659) @ javax.swing.text.jtextcomponent.settext(jtextcomponent.java:1718) @ opa.beta1.textfieldevent.setciphertext(textfieldevent.java:82) @ opa.beta1.textfieldevent$1.removeupdate(textfieldevent.java:33) 

this line

setjpanel(ciphertextarray, panel3, "1"); 

also adds documentlistener every element of ciphertextarray textfield. every time value of 1 of cipher text textfields changes, method setciphertext() invoked.

this leads following sequence:

1. you enter new value in 1 of textfields of arrayiv or plaintextarray
2. setciphertext() invoked
3. setciphertext() changes value of cipher text textfield
4. setciphertext() again invoked (explanation above). go 2.

thats why illegalstateexception.

so solution not add documentlistener textfields in ciphertextarray.

solution implemented follows:

public void setjpanel(jtextfield array[], jpanel container, string s, boolean doclistener) {     (int = 0; < 8; i++) {         array[i] = new jtextfield(s, 4);         if (doclistener) {             array[i].getdocument().adddocumentlistener(new documentlistener() {                 @override                 public void insertupdate(documentevent de) {                     setciphertext();                 }                  @override                 public void removeupdate(documentevent de) {                     setciphertext();                 }                  @override                 public void changedupdate(documentevent de) {                     setciphertext();                 }             });         }         container.add(array[i]);     } }  [...]      setjpanel(arrayiv, panel1, "1a", true);     setjpanel(plaintextarray, panel2, "1b", true);     setjpanel(ciphertextarray, panel3, "1", false);