Il metodo parseDouble della classe Java Double restituisce un nuovo valore double che viene inizializzato sul valore corrispondente alla String definita.

Questo metodo viene eseguito come il metodo valueOf() della classe Float.

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Sintassi

 public static double parseDouble(String s) throws NumberFormatException 

Parametri

S- Questa è la stringa da analizzare.

Valore di ritorno

Il metodo parseDouble() restituisce il valore double corrispondente al parametro passato.

Lancia

Il metodo parseDouble() lancia:

1. NullPointerException- se la stringa passata è nulla.

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2. NumberFormatException- se la stringa passata non contiene un float analizzabile.

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Esempio 1

 public class Double_parseDoubleMethodExample1 { public static void main(String[] args) { String val1='1000'; String val2='156'; //here instead of adding it will concatenate two Strings //but will convert the String into Float Double d = Double.parseDouble(val1+val2); System.out.println('1. Sum ='+d); Double f1 = Double.parseDouble(val1)+Double.parseDouble(val2); System.out.println('2. Sum ='+f1); Double f2 = Double.parseDouble(val1)*Double.parseDouble(val2); System.out.println('3. Multiplication ='+f2); Double f3 = Double.parseDouble(val1)/Double.parseDouble(val2); System.out.println('4. Division ='+f3); Double f4 = Double.parseDouble(val1)%Double.parseDouble(val2); System.out.println('5. Reminder ='+f4); } } 

Produzione:

 1. Sum =1000156.0 2. Sum =1156.0 3. Multiplication =156000.0 4. Division =6.410256410256411 5. Reminder =64.0 

Esempio 2

 import java.util.Scanner; public class Double_parseDoubleMethodExample2 { public static void main(String[] args) { Scanner scanner = new Scanner(System.in); System.out.print(&apos;Enter your age:&apos;); String str = scanner.next(); // Double d1 = Double.parseDouble(str); Double d2 = 2018 - d1 ; System.out.println(&apos;Your year of birth is = &apos;+d2); if(d2<1965){ system.out.println('you are an adult, you eligible for the discount in railway tickets.'); } else{ double d3="d2-1965;" system.err.println('sorry! not eligible.try again after '+d3+' years'); < pre> <span> Test it Now </span> <p> <strong>Output:</strong> </p> <pre> Enter your age:09 Sorry! You are not eligible.Try again after 44.0 years Your year of birth is = 2009.0 </pre> <h2>Example 3</h2> <pre> import java.util.Scanner; public class Double_parseDoubleMethodExample3 { public static void main(String[] args) { Scanner scanner = new Scanner(System.in); System.out.print(&apos;Enter any string:&apos;); String str = scanner.next(); Double d1= Double.parseDouble(str); System.out.println(&apos;Double value = &apos;+ d1); } } </pre> <span> Test it Now </span> <p> <strong>Output:</strong> </p> <pre> Enter any string:Himanshu@123 Exception in thread &apos;main&apos; java.lang.NumberFormatException: For input string: &apos;Himanshu@123&apos; at sun.misc.FloatingDecimal.readJavaFormatString(FloatingDecimal.java:2043) at sun.misc.FloatingDecimal.parseDouble(FloatingDecimal.java:110) at java.lang.Double.parseDouble(Double.java:538) </pre> <h2>Example 4</h2> <pre> import java.util.Scanner; public class Double_parseDoubleMethodExample4 { public static void main(String[] args) { Scanner scanner = new Scanner(System.in); try { System.out.print(&apos;Enter any string:&apos;); String str = scanner.next(); Double d1 = Double.parseDouble(str); String str1=&apos;null&apos;; Double d2 = Double.parseDouble(str1); System.out.println(&apos;1. Double value = &apos; + d1); System.out.println(&apos;2. Double value = &apos; + d2); }catch (NullPointerException e){ System.out.println(&apos;An exception &apos;+e+&apos; has occured.
Plz enter a valid double integer&apos;); }catch (NumberFormatException ex){ System.out.println(&apos;An exception &apos;+ex+&apos; has occured.
Plz enter a valid double integer&apos;); } } } </pre> <span> Test it Now </span> <p> <strong>Output:</strong> </p> <pre> Enter any string:himanshu@123 An exception java.lang.NumberFormatException: For input string: &apos;himanshu@123&apos; has occured. Plz enter a valid double integer </pre> <br></1965){>

Esempio 3

 import java.util.Scanner; public class Double_parseDoubleMethodExample3 { public static void main(String[] args) { Scanner scanner = new Scanner(System.in); System.out.print('Enter any string:'); String str = scanner.next(); Double d1= Double.parseDouble(str); System.out.println('Double value = '+ d1); } } 

Produzione:

 Enter any string:Himanshu@123 Exception in thread 'main' java.lang.NumberFormatException: For input string: 'Himanshu@123' at sun.misc.FloatingDecimal.readJavaFormatString(FloatingDecimal.java:2043) at sun.misc.FloatingDecimal.parseDouble(FloatingDecimal.java:110) at java.lang.Double.parseDouble(Double.java:538) 

Esempio 4

 import java.util.Scanner; public class Double_parseDoubleMethodExample4 { public static void main(String[] args) { Scanner scanner = new Scanner(System.in); try { System.out.print('Enter any string:'); String str = scanner.next(); Double d1 = Double.parseDouble(str); String str1='null'; Double d2 = Double.parseDouble(str1); System.out.println('1. Double value = ' + d1); System.out.println('2. Double value = ' + d2); }catch (NullPointerException e){ System.out.println('An exception '+e+' has occured.
Plz enter a valid double integer'); }catch (NumberFormatException ex){ System.out.println('An exception '+ex+' has occured.
Plz enter a valid double integer'); } } } 

Produzione:

 Enter any string:himanshu@123 An exception java.lang.NumberFormatException: For input string: 'himanshu@123' has occured. Plz enter a valid double integer