Java – jtextarea contains only numbers, but negative values are allowed

I have a jtextarea, just accept numbers This is my code:

DocumentFilter onlyNumberFilter = new AxisJTextFilter();
    final JTextArea areaTextoXMin = new JTextArea(String.valueOf(xMin));
    ((AbstractDocument)areaTextoXMin.getDocument()).setDocumentFilter(onlyNumberFilter);

Applies to positive numbers, but not negative numbers How can I solve this problem?

Editor: sorry, axisjtextfilter was found on the Internet, I forgot Its code is:

import javax.swing.text.*;
import java.util.regex.*;

public class AxisJTextFilter extends DocumentFilter
{
    public void insertString(DocumentFilter.FilterBypass fb,int offset,String text,AttributeSet attr) throws BadLocationException
    {
        StringBuilder sb = new StringBuilder();
        sb.append(fb.getDocument().getText(0,fb.getDocument().getLength()));
        sb.insert(offset,text);
        if(!containsOnlyNumbers(sb.toString())) return;
        fb.insertString(offset,text,attr);
    }
    public void replace(DocumentFilter.FilterBypass fb,int length,fb.getDocument().getLength()));
        sb.replace(offset,offset + length,text);
        if(!containsOnlyNumbers(sb.toString())) return;
        fb.replace(offset,length,attr);
    }
    public boolean containsOnlyNumbers(String text)
    {
        Pattern pattern = Pattern.compile("\\d*(\\.\\d{0,3})?");
        Matcher matcher = pattern.matcher(text);
        boolean isMatch = matcher.matches();
        return isMatch;
    }
}

Solution

Try modifying the regular expression (int validation method containsonlynumbers)

Pattern pattern = Pattern.compile("^[\\-\\+]?\\d+(\\.\\d+)?$");

This will accept the following numbers:

> 1234 > -1234 > 1234 > 1234.1234

I hope it helps

UDI