Compruebe si un doble no es un número en Java
double delta = -3;
double val = Math.sqrt(delta);
System.out.println(Double.isNaN(val)); // true
Wissam
double delta = -3;
double val = Math.sqrt(delta);
System.out.println(Double.isNaN(val)); // trueString decimalPattern = "([0-9]*)\\.([0-9]*)";
String number="20.00";
boolean match = Pattern.matches(decimalPattern, number);
System.out.println(match); //if true then decimal else not