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 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();
}
} |
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 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);
}
}
} |
Exception thrown: java.util.InputMismatchException
Program 3: To demonstrate NoSuchElementException
// 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);
}
}
} |
Not found Double value :Gfg Exception thrown: java.util.NoSuchElementException
Program 4: To demonstrate IllegalStateException
// 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);
}
}
} |
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()