java scanner

扫描仪类的nextDouble()方法 (Scanner Class nextDouble() method)

• nextDouble() method is available in java.util package.

  nextDouble()方法在java.util包中可用。

• nextDouble() method is used to scans the next token of the input scanned into a double value.

  nextDouble()方法用于将输入的下一个标记扫描为双精度值。

• nextDouble() method is a non-static method, it is accessible with the class object only and if we try to access the method with the class name then we will get an error.

  nextDouble()方法是一个非静态方法，只能通过类对象访问，如果尝试使用类名称访问该方法，则会收到错误消息。

• nextDouble() method may throw an exception at the time of returning a double value.

  返回双精度值时， nextDouble()方法可能会引发异常。

  • InputMismatchException: This exception may throw when the next token input mismatch.InputMismatchException ：下一个令牌输入不匹配时，可能引发此异常。
  • NoSuchElementException: This exception may throw when no such element exists.NoSuchElementException ：如果不存在这样的元素，则可能引发此异常。
  • IllegalStateException: This exception may throw when this Scanner is not opened.IllegalStateException ：如果未打开此扫描器，则可能引发此异常。

Syntax:

句法：

    public double nextDouble();

Parameter(s):

参数：

• It does not accept any parameter.

  它不接受任何参数。

Return value:

返回值：

The return type of the method is double, it returns double value for the input.

方法的返回类型为double ，它为输入返回double值。

Example:

例：

// Java program to demonstrate the example 
// of double nextDouble() method of Scanner 
import java.util.*;
public class NextDoubleOfScanner {
public static void main(String[] args) {
String str = "Hi, Includehelp! 8 + 2.0 = 10.0 true";
// Instantiate Scanner with the 
// given str
Scanner sc = new Scanner(str);
// Loop for scanning the double
// token input
while (sc.hasNext()) {
// if double then display it
if (sc.hasNextDouble()) {
System.out.println("Double Exists: " + sc.nextDouble());
}
sc.next();
}
// close the scanner
sc.close();
}
}

Output

输出量

Double Exists: 8.0
Double Exists: 2.0
Double Exists: 10.0

翻译自: https://www.includehelp.com/java/scanner-nextdouble-method-with-example.aspx

java scanner