extends PlainDocument : Document Event « Swing JFC « Java

extends PlainDocument


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import javax.swing.text.AttributeSet;
import javax.swing.text.BadLocationException;
import javax.swing.text.PlainDocument;

 * Helper class. Only allows an Double value in the document.
 * @author <a href="mailto:vhardy@apache.org">Vincent Hardy</a>
 * @version $Id: DoubleDocument.java 504084 2007-02-06 11:24:46Z dvholten $
public class DoubleDocument extends PlainDocument {

     * Strip all non digit characters.  The first character must be '-' or '+'.
     * Only one '.' is allowed.
    public void insertString(int offs, String str, AttributeSet a)
            throws BadLocationException {

        if (str == null) {

        // Get current value
        String curVal = getText(0, getLength());
        boolean hasDot = curVal.indexOf('.') != -1;

        // Strip non digit characters
        char[] buffer = str.toCharArray();
        char[] digit = new char[buffer.length];
        int j = 0;

        if(offs==0 && buffer!=null && buffer.length>0 && buffer[0]=='-')
            digit[j++] = buffer[0];

        for (int i = 0; i < buffer.length; i++) {
                digit[j++] = buffer[i];
            if(!hasDot && buffer[i]=='.'){
                digit[j++] = '.';
                hasDot = true;

        // Now, test that new value is within range.
        String added = new String(digit, 0, j);
            StringBuffer val = new StringBuffer(curVal);
            val.insert(offs, added);
            String valStr = val.toString();
            if( valStr.equals(".") || valStr.equals("-") || valStr.equals("-."))
                super.insertString(offs, added, a);
                Double.valueOf( valStr );
                super.insertString(offs, added, a);
        }catch(NumberFormatException e){
            // Ignore insertion, as it results in an out of range value

    public void setValue(double d){
            remove(0, getLength());
            insertString(0, String.valueOf( d ), null);
        }catch(BadLocationException e){
            // Will not happen because we are sure
            // we use the proper range

    public double getValue(){
            String t = getText(0, getLength());
            if(t != null && t.length() > 0){
                return Double.parseDouble(t);
                return 0;
        }catch(BadLocationException e){
            // Will not happen because we are sure
            // we use the proper range
            throw new Error( e.getMessage() );


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