Det nextDouble() er en metode i Java Scanner-klassen, som bruges til at scanne det næste token af ​​input som en dobbelt. Hvis oversættelsen lykkes, passerer scanneren det input, der matchede.

Syntaks

Følgende er erklæringen af nextDouble() metode:

java streng sammenkædning

 public double nextDouble() 

Parameter

Denne metode accepterer ikke nogen parameter.

Vender tilbage

Det nextDouble() metoden returnerer den dobbeltscannede fra inputtet.

Undtagelser

InputMismatchException - Det vil kaste denne undtagelse, hvis det næste token ikke matcher det regulære Float-udtryk, eller er uden for rækkevidde.

NoSuchElementException - Det vil kaste denne undtagelse, hvis input er opbrugt.

for hver maskinskrift

IllegalStateException - Det vil kaste denne undtagelse, hvis påkaldelsen sker efter Scanner er lukket.

Kompatibilitetsversion

Java 1.5 og nyere

Eksempel 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(); } } 

Produktion:

java streng trim

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

Eksempel 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(); } } 

Produktion:

 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 

Eksempel 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() } } 

Produktion:

 Enter value: 375437.565 Your entered Double value: 375437.565 

Eksempel 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(); } } 

Produktion:

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