Use java's Scanner.nextDouble() function to read the next double precision floating point input

Use java's Scanner.nextDouble() function to read the next double-precision floating point input

The Scanner class is a commonly used tool class in Java for reading users from the console or other input sources. Entered data. The Scanner class provides many methods to read different types of input, including integers, floating point numbers, strings, etc. Among them, the nextDouble() function can be used to read the next double-precision floating point input.

The following is a sample code that demonstrates how to use the Scanner.nextDouble() function to read double-precision floating point input:

import java.util.Scanner;

public class ReadDoubleInput {
    public static void main(String[] args) {
        // 创建Scanner对象
        Scanner scanner = new Scanner(System.in);

        // 提示用户输入
        System.out.print("请输入一个双精度浮点数: ");

        // 读取双精度浮点数输入
        double input = scanner.nextDouble();

        // 输出读取到的浮点数
        System.out.println("您输入的双精度浮点数为: " + input);

        // 关闭Scanner对象
        scanner.close();
    }
}

In the above code, we first create a Scanner object, and then Use the nextDouble() method to read the double-precision floating point number entered by the user. When executing this method, the program will wait for the user to enter a double-precision floating point number on the console, and then assign the entered value to the input variable. Finally, we output the floating point number we read.

It should be noted that the nextDouble() method can only read floating point numbers. If the content input by the user cannot be parsed as a floating point number, an InputMismatchException will be thrown. Therefore, before reading a double precision floating point number, it is recommended to do some validation of the user's input to ensure that what the user enters is as expected.

In addition, when using the Scanner class to read input, the system will split the input into multiple tokens based on default delimiters (such as spaces, tabs, newlines, etc.). The nextDouble() method reads and returns the next token as a double precision floating point number. If there is no next floating point number token in the input, a NoSuchElementException will be thrown.

To sum up, the nextDouble() method of the Scanner class provides a convenient way to read the double-precision floating point number entered by the user. In actual applications, we can combine other methods and logic to process and verify user input as needed to achieve more complete functions.

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