Use java's Scanner.useLocale() function to set the locale for input parsing

Use Java's Scanner.useLocale() function to set the locale for input parsing

In Java programming, the Scanner class is a convenient tool for taking input from the standard input stream (keyboard) or other Read basic types and strings from streams. The Scanner class provides many useful methods, but in some cases it may be necessary to parse input based on a specific locale. To solve this problem, we can use the useLocale() function of the Scanner class to set the locale for input parsing.

The useLocale(Locale locale) function of the Scanner class is used to set the locale used by the Scanner when parsing input. A locale is a specification used in different regions to determine how data is formatted and text is interpreted. The Locale class in Java represents an identifier for a specific region, including country, language and dialect information.

The steps to use the Scanner.useLocale() function are as follows:

1. Create a Scanner object and pass the input stream to it as a parameter. For example:

   Scanner scanner = new Scanner(System.in);

2. Use the constructor of the Locale class to create a specific locale object. For example, to create an English (United States) locale object:

   Locale locale = new Locale("en", "US");

3. Call the Scanner object's useLocale(Locale locale) function, passing the specific locale object as a parameter. For example:

   scanner.useLocale(locale);

Next, let’s look at a simple example. Let's say we want to input a floating point number from the keyboard and use the German (Germany) locale to parse the input.

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

public class LocaleExample {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        
        Locale locale = new Locale("de", "DE");
        scanner.useLocale(locale);
        
        System.out.print("请输入一个浮点数：");
        double number = scanner.nextDouble();
        
        System.out.println("输入的浮点数是：" + number);
        
        scanner.close();
    }
}

In the above example, we first create a Scanner object and use System.in as its input stream. We then create a German (Germany) locale object using the constructor of the Locale class. Next, we call the useLocale() function of the Scanner object and pass it the German locale object as a parameter. Finally, we enter a floating point number from the keyboard using the nextDouble() function and store it in the variable number. We then print the entered float to the console.

Run the above code example, you can see that the program will wait for the user to enter a floating point number. When the user has finished typing, the program will parse the input using the German locale and print the parsed floating point number to the console.

Summary:

The Scanner class is an important tool in Java for reading data from the input stream. Use the Scanner.useLocale() function to set the locale for input parsing so that data is formatted and interpreted according to a specific locale. By rationally using locale settings, we can handle input data in different languages ​​and regions, improving the flexibility and internationalization capabilities of the program.

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