JAVA

Check whether a double is not a number in java

double delta = -3;
double val = Math.sqrt(delta);
System.out.println(Double.isNaN(val)); // true

how to check if string is double or not in java

String 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  

how to tell if a number is an int or a double java

if (x % 1 == 0)  // true: it's an integer, false: it's not an integer