Scanner hasNextDouble() method in Java with Examples
The hasNextDouble() method of java.util.Scanner class returns true if the next token in this scanner’s input can be interpreted as a Double using the nextDouble() method. The scanner does not advance past any input.
Syntax:
public Double hasNextDouble()
Parameters: The function does not accepts any parameter.
Return Value: This function returns true if and only if this scanner’s next token is a valid Double.
Exceptions: The function throws IllegalStateException if this scanner is closed.
Below programs illustrate the above function:
Program 1:
// Java program to illustrate the// hasNextDouble() method of Scanner class in Java// without parameter import java.util.*; public class GFG1 { public static void main(String[] argv) throws Exception { String s = "gfg 2 geeks!"; // new scanner with the // specified String Object Scanner scanner = new Scanner(s); // use US locale to interpret Doubles in a string scanner.useLocale(Locale.US); // iterate till end while (scanner.hasNext()) { // check if the scanner's // next token is a Double with the default radix System.out.print("" + scanner.hasNextDouble()); // print what is scanned System.out.print(" -> " + scanner.next() + "\n"); } // close the scanner scanner.close(); }} |
Output:
false -> gfg true -> 2 false -> geeks!
Program 2: Program to demonstrate exception
// Java program to illustrate the// hasNextDouble() method of Scanner class in Java// Exception case import java.util.*; public class GFG1 { public static void main(String[] argv) throws Exception { try { String s = "gfg 2 geeks!"; // new scanner with the // specified String Object Scanner scanner = new Scanner(s); // use US locale to interpret Doubles in a string scanner.useLocale(Locale.US); scanner.close(); // iterate till end while (scanner.hasNext()) { // check if the scanner's // next token is a Double with the default radix System.out.print("" + scanner.hasNextDouble()); // print what is scanned System.out.print(" -> " + scanner.next() + "\n"); } // close the scanner scanner.close(); } catch (IllegalStateException e) { System.out.println("Exception: " + e); } }} |
Output:
Exception: java.lang.IllegalStateException: Scanner closed
Reference: https://docs.oracle.com/javase/7/docs/api/java/util/Scanner.html#hasNextDouble()
