text.append("\t" + nf1.formatString("Points") +
"\t" + nf2.formatString("Values") + "\n\n");
for(int i = 0; i <= size() - 1; i++) {
text.append( "\t" + nf1.format( points.get(i) ) + "\t" +
nf2.format( values.get(i) ) + "\n" );
}
return text.toString();
}