How to create your own numeric components ?

[Geert Van Landeghem <gvl@xxxxxxxxxxxxxx>]

Hi All,

I'm trying to create my own numeric textfields: I've created a subclass of
JTextField and I'm using the KeyPressed 
method to obtain control over digits and separators entered.

Is there a way to obtain the position of the cursor in the field when
generating each KeyEvent?

when using the following code:
   JRNumField jrn_myfield=new JRNumField(6,2, '.');
   // creates a numeric textfield with 6 positions and 2 decimals and '.' as
separator
following valid values can be entered:
  1234.56
  12.56
  1234
  ...
but also:
  12.234
  12221.1
To resolve this problem I need a way to obtain the position of the cursor
(before or after the separator)
Has anybody an idea how to do this or are there some 'home-made' components
already available with the
the same functionality?

the code I'm using in keyPressed follows:

/**
 * This method was created in VisualAge.
 * @param ke java.awt.event.KeyEvent
 */
public void keyTyped(KeyEvent ke) {
  // getLength() returns total number of digits
  // getDecimals() returns the digits after the separator
  // getNotation returns the type of separator (comma or period)
  char typedChar=ke.getKeyChar();
  int length= getPositions();
 
  // calculate the position of the separator
  int pos=getText().indexOf(getNotation());
  // set separator to true if separator has allready been entered 
  boolean separator=pos > -1;

  System.out.println("Keyevent=" + ke); 
 
  // calculate the maximum total length in characters
  // if decimals specified add 1 to total length(separator)
  if (getDecimals() > 0) {
        length++;
  }
  // logging
  System.out.println("Event = " + ke + getText());
  
  // if length of field is equal to maximum length-1
  // consume the KeyEvent: throw it away!
  if (getText().length() > length-1){
          if (getSelectedText().compareTo(getText())==0) {
                  setText("");
                  return;
          }       
          System.out.println("String to long");
          ke.consume();
          return;
  }
  
  
  // test the character being entered
  // is character a digit?
  else if (Character.isDigit(typedChar)) {  
          System.out.println("It is a digit!");
          // if decimals specified and seperator has been found
          if (getDecimals() > 0 && separator) {
              int numBefore=pos;
                  int numAfter=getText().length()- (pos+1);
                  // is number of digits before or after seperator reached?
                  // logging
                  System.out.println("Length= " + getText().length() + "
Position= " + pos + " before="+ numBefore + " numAfter=" + numAfter + "
decimals=" +getDecimals());
                  if  (numBefore <= getPositions()-getDecimals() && numAfter
<= getDecimals()) {
                     return;
                     // !! not correct !!
                     // !! you need to know the position where the character
has been entered...
                     // !! (where the KeyEvent is being generated)
                  }
                  else {
                          ke.consume();
                          return;
                  }       
          }       
          else if (getDecimals() > 0 && !separator) {
                  // if decimals specified and no seperator has been found

              if (getText().length() > getPositions()-getDecimals()-1) {
                          ke.consume();
                          return;
                  }
                  return;
          }    
  }
  
  // is character equal to separator?
  else if (ke.getKeyChar()== getNotation() && getDecimals() > 0){
          System.out.println("It is a seperator!");
          // if seperator has allready been used?
          if (separator) {
                  System.out.println("Separator has already been used");
                  ke.consume();
          }
          else {
                  System.out.println("This is the separator!");
                  return;                 
          }
  }
  
  // no valid character entered
  // throw away event
  else {
          System.out.println("No seperator and no digit!");
          ke.consume();
          return;
  }       
}


----------------------------------------------------------------------------
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Geert Van Landeghem
Reynders Etiketten
gvl@reynderseti.be (Office)
hydra@vt4.net (Home)
03/460.12.56 (Office)
0477/759.533 (GSM)

<<never play leapfrog with a unicorn>>
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