Scanner nextDouble() method in Java with Examples
Last Updated :
12 Oct, 2018
The
nextDouble() method of
java.util.Scanner class scans the next token of the input as a Double. If the translation is successful, the scanner advances past the input that matched.
Syntax:
public double nextDouble()
Parameters: The function does not accepts any parameter.
Return Value: This function returns the
Double scanned from the input.
Exceptions: The function throws three exceptions as described below:
- InputMismatchException: if the next token does not matches the Double regular expression, or is out of range
- NoSuchElementException: throws if input is exhausted
- IllegalStateException: throws if this scanner is closed
Below programs illustrate the above function:
Program 1:
Java
// Java program to illustrate the
// nextDouble() 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 9 + 6 = 12.0";
// create a new scanner
// with the specified String Object
Scanner scanner = new Scanner(s);
while (scanner.hasNext()) {
// if the next is a Double,
// print found and the Double
if (scanner.hasNextDouble()) {
System.out.println("Found Double value :"
+ scanner.nextDouble());
}
// if no Double is found,
// print "Not Found:" and the token
else {
System.out.println("Not found Double() value :"
+ scanner.next());
}
}
scanner.close();
}
}
Output:
Not found Double() value :Gfg
Found Double value :9.0
Not found Double() value :+
Found Double value :6.0
Not found Double() value :=
Found Double value :12.0
Program 2: To demonstrate InputMismatchException
Java
// Java program to illustrate the
// nextDouble() method of Scanner class in Java
// InputMismatchException
import java.util.*;
public class GFG1 {
public static void main(String[] argv)
throws Exception
{
try {
String s = "Gfg 9 + 6 = 12.0";
// create a new scanner
// with the specified String Object
Scanner scanner = new Scanner(s);
while (scanner.hasNext()) {
// if the next is a Double
// print found and the Double
// since the value 60 is out of range
// it throws an exception
System.out.println("Next Double value :"
+ scanner.nextDouble());
}
scanner.close();
}
catch (Exception e) {
System.out.println("Exception thrown: " + e);
}
}
}
Output:
Exception thrown: java.util.InputMismatchException
Program 3: To demonstrate NoSuchElementException
Java
// Java program to illustrate the
// nextDouble() method of Scanner class in Java
// NoSuchElementException
import java.util.*;
public class GFG1 {
public static void main(String[] argv)
throws Exception
{
try {
String s = "Gfg";
// create a new scanner
// with the specified String Object
Scanner scanner = new Scanner(s);
// Trying to get the next Double value
// more times than the scanner
// Hence it will throw exception
for (int i = 0; i < 5; i++) {
// if the next is a Double,
// print found and the Double
if (scanner.hasNextDouble()) {
System.out.println("Found Double value :"
+ scanner.nextDouble());
}
// if no Double is found,
// print "Not Found:" and the token
else {
System.out.println("Not found Double value :"
+ scanner.next());
}
}
scanner.close();
}
catch (Exception e) {
System.out.println("Exception thrown: " + e);
}
}
}
Output:
Not found Double value :Gfg
Exception thrown: java.util.NoSuchElementException
Program 4: To demonstrate IllegalStateException
Java
// Java program to illustrate the
// nextDouble() method of Scanner class in Java
// IllegalStateException
import java.util.*;
public class GFG1 {
public static void main(String[] argv)
throws Exception
{
try {
String s = "Gfg 9 + 6 = 12.0";
// create a new scanner
// with the specified String Object
Scanner scanner = new Scanner(s);
// close the scanner
scanner.close();
System.out.println("Scanner Closed");
System.out.println("Trying to get "
+ "next Double value");
while (scanner.hasNext()) {
// if the next is a Double,
// print found and the Double
if (scanner.hasNextDouble()) {
System.out.println("Found Double value :"
+ scanner.nextDouble());
}
// if no Double is found,
// print "Not Found:" and the token
else {
System.out.println("Not found Double value :"
+ scanner.next());
}
}
}
catch (Exception e) {
System.out.println("Exception thrown: " + e);
}
}
}
Output:
Scanner Closed
Trying to get next Double value
Exception thrown: java.lang.IllegalStateException: Scanner closed
Reference: https://docs.oracle.com/javase/7/docs/api/java/util/Scanner.html#nextDouble()