java – 具有扫描器#nextFloat的奇怪行为

price = sc.nextFloat();

在代码之前添加此行使扫描程序接受0,23(法语符号)作为浮点数：

Locale.setDefault(Locale.US);

这很可能是由于Windows XP Pro(法语/比利时)中的区域设置.当代码再次运行时,23仍然被接受并且输入0.23导致它抛出一个java.util.InputMismatchException.

任何解释为什么会发生这种情况？还有一个解决方法,还是应该使用Float#parseFloat？

编辑：这演示了扫描仪的行为与不同的区域设置(取消注释开头的行之一).

import java.util.Locale;
import java.util.Scanner;


public class NexFloatTest {

    public static void main(String[] args) {

        //Locale.setDefault(Locale.US);
        //Locale.setDefault(Locale.FRANCE);

        // Gives fr_BE on this system
        System.out.println(Locale.getDefault());

        float price;

        String uSDecimal = "0.23";
        String frenchDecimal = "0,23";

        Scanner sc = new Scanner(uSDecimal);

        try{
            price = sc.nextFloat();
            System.out.println(price);
        } catch (java.util.InputMismatchException e){
            e.printStackTrace();
        }

        try{
            sc = new Scanner(frenchDecimal);
            price = sc.nextFloat();
            System.out.println(price);
        } catch (java.util.InputMismatchException e){
            e.printStackTrace();
        }

        System.out.println("Switching Scanner to System.in");

        try{
            sc = new Scanner(System.in);
            System.out.println("Enter a float value");
            price = sc.nextFloat();
            System.out.println(price);
        } catch (java.util.InputMismatchException e){
            e.printStackTrace();
        }

        System.out.print("Enter title:");

        String title = sc.nextLine(); // This line is skipped

        System.out.print(title);
    }

}

编辑：这会重现扫描仪正在等待浮点值的问题,但当您按回车时无法触发：

import java.util.Scanner;

public class IgnoreCRTest {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        System.out.println("Enter a float value:");
        // On french Locale use,as the decimal separator
        float testFloat = sc.nextFloat();
        System.out.println(testFloat);
        //sc.skip("n"); // This doesn't solve the issue
        sc.nextLine();
        System.out.println("Enter an integer value:");
        int testInt = sc.nextInt();
        System.out.println(testInt);
        // Will either block or skip here
        System.out.println("Enter a string value :");
        String testString = sc.nextLine();
        System.out.println(testString);
    }

}