java - jtextfield documentFilter once defined, value not loading in the jtextfield -

i have jtextfield named tpvv, wrote documentfilter accept numbers, maximum length of 3.and have button edit, when click button entire row loaded in textfield's editing jtable(value in jtextfield tpvv remains constant). jtextfield defined without documentfilter works well(loads values jtable textfields based on row selection). when comment documentfilter works well, cannot provide validation (accept number , length of 3).

i need check validation tpvv , load values jtable based on different row selection clicking edit button.

`class numericandlengthfilter extends documentfilter {          /**          * number of characters allowed.          */         private int length = 0;          /**          * restricts number of charcacters can entered given length.          * @param length number of characters allowed.          */         public numericandlengthfilter(int length) {             this.length = length;         }          @override         public void insertstring(filterbypass fb, int offset, string string,                 attributeset attr) throws                 badlocationexception {             if (isnumeric(string)) {                 if (this.length > 0 && fb.getdocument().getlength() + string.                         length()                         > this.length) {                     return;                 }                 super.insertstring(fb, offset, string, attr);             }         }          @override         public void replace(filterbypass fb, int offset, int length, string text,                 attributeset attrs) throws                 badlocationexception {             if (isnumeric(text)) {                 if (this.length > 0 && fb.getdocument().getlength() + text.                         length()                         > this.length) {                     return;                 }                 super.insertstring(fb, offset, text, attrs);             }         }          /**          * method tests whether given text can represented number.          * method can enhanced further specific needs.          * @param text input text.          * @return {@code true} if given string can converted number; otherwise returns {@code false}.          */         private boolean isnumeric(string text) {             if (text == null || text.trim().equals("")) {                 return false;             }             (int icount = 0; icount < text.length(); icount++) {                 if (!character.isdigit(text.charat(icount))) {                     return false;                 }             }             return true;         }  } //((abstractdocument) tpvv.getdocument()).setdocumentfilter(new numericandlengthfilter(3)); 

`last commented line defined in code validation purpose call. please solve problem.

you're ignoring parameters passed , mean...

• offset offset within document new text inserted...
• length number of characters deleted

now, if use length within if statement, start see difference. basically, when call settext, length equal number of characters in text field (as text replaced)...

public void replace(filterbypass fb, int offset, int length, string text,                 attributeset attrs) throws                 badlocationexception {     if (isnumeric(text)) {          system.out.println(offset + "; " + length + "; " + text);          if (this.length > 0 &&              fb.getdocument().getlength() + text.length() - length > this.length) {             return;         }         super.replace(fb, offset, length, text, attrs);     } } 

you're calling super.insertstring(fb, offset, text, attrs); in replace method, isn't helpful either...

update comments

the problem you're facing settext(null) fact isnumeric in filter returning false null , empty ("") values, these valid in contexts...

now, alter isnumeric method, might adversely affect other methods of filter, instead, should place additional condition in replace catch case , deal appropriately...

public void replace(filterbypass fb, int offset, int length, string text,                 attributeset attrs) throws                 badlocationexception {     if (isnumeric(text)) {          system.out.println(offset + "; " + length + "; " + text);          if (this.length > 0 &&              fb.getdocument().getlength() + text.length() - length > this.length) {             return;         }         super.replace(fb, offset, length, text, attrs);     } else if (text == null || text.equals("")) {         super.replace(fb, offset, length, text, attrs);     } }