Lim_Dul hat gesagt.:http://java.sun.com/j2se/1.5.0/docs/api/java/awt/FontMetrics.html#stringWidth(java.lang.String)
Font myFont = new Font("MyFont", Font.PLAIN, 12);
FontMetrics fm = new FontMetrics(myFont);
String myString = "StringDessenBreiteIchWissenWill";
int myStringWidth = fm.stringWidth(myString);