The nextDouble() je metóda triedy Java Scanner, ktorá sa používa na skenovanie nasledujúceho tokenu vstupu ako dvojitého. Ak je preklad úspešný, skener minul vstup, ktorý sa zhodoval.

Syntax

Nasleduje vyhlásenie o nextDouble() metóda:

 public double nextDouble() 

Parameter

Táto metóda neakceptuje žiadny parameter.

Návraty

The nextDouble() metóda vráti dvojité skenovanie zo vstupu.

Výnimky

InputMismatchException - Túto výnimku vyvolá, ak sa nasledujúci token nezhoduje s regulárnym výrazom Float alebo je mimo rozsahu.

NoSuchElementException - Túto výnimku vyvolá, ak je vstup vyčerpaný.

IllegalStateException - Túto výnimku vyvolá, ak sa vyvolanie vykoná po zatvorení skenera.

Verzia kompatibility

Java 1.5 a vyššie

Príklad 1

 import java.util.*; public class ScannerNextDoubleExample1 { public static void main(String args[]){ int amount; double balance; //Insert amount and balance from console Scanner input = new Scanner (System.in); System.out.println('Enter the amount: '); amount = input.nextInt(); System.out.println('Enter the Total Balance: '); balance = input.nextDouble(); //reduce amount+fee from balance balance=balance-(amount + 0.50); //print new balance System.out.print('Left Balance is: '+balance); input.close(); } } 

Výkon:

 Enter the amount: 213734 Enter the Total Balance: 5684566.856 Left Balance is: 5470832.356 

Príklad 2

 import java.util.*; public class ScannerNextDoubleExample2 { public static void main(String args[]){ String str = 'Hello World! 12 + 13.0 = 15 '; Float f = 2.123f; str = str + f; //Create a new scanner with string Object Scanner scanner = new Scanner(str); //Use US locale to be able to identify doubles in the string scanner.useLocale(Locale.US); //Find the next double token and print it while (scanner.hasNext()) { //Check if the next is a double, print found if (scanner.hasNextDouble()) { System.out.println('Found Double:' + scanner.nextDouble()); } //If double is not found, print 'Not Found' System.out.println('Not Found Double:' + scanner.next()); } scanner.close(); } } 

Výkon:

 Not Found Double:Hello Not Found Double:World! Found Double:12.0 Not Found Double:+ Found Double:13.0 Not Found Double:= Found Double:15.0 Not Found Double:2.123 

Príklad 3

 import java.util.*; public class ScannerNextDoubleExample3 { public static void main(String args[]){ Scanner scan = new Scanner(System.in); System.out.print('Enter value: '); if(scan.hasNextDouble()) { double y = scan.nextDouble(); System.out.println('Your entered Double value: ' +y); } else if (scan.hasNext()) { System.out.println('Please Entered the Double Value.'); System.out.println('You entered: ' + scan.next()); } scan.close() } } 

Výkon:

 Enter value: 375437.565 Your entered Double value: 375437.565 

Príklad 4

 import java.util.*; public class ScannerNextDoubleExample4 { public static void main(String args[]){ double value; Scanner scan = new Scanner(System.in); System.out.print('Enter the numeric value : '); value = scan.nextDouble(); System.out.println('Double value : ' + value +' 
Twice value : ' + 2.0*value ); scan.close(); } } 

Výkon:

 Enter the numeric value : 12345 Double value : 12345.0 Twice value : 24690.0