Learn Internationalization with String.format()

When you build applications for a global audience, you must ensure that your output is tailored to the conventions of each user's region. Locale-sensitive formatting is essential for internationalization, which means designing your program so it can adapt to different languages, regions, and cultural norms. Java's String.format() method provides built-in support for locale-aware formatting, allowing you to present numbers, dates, and text in ways that match regional standards. This is especially important for numbers, where decimal separators, grouping symbols, and even the order of elements can differ from country to country.

Main.java


              123456789101112131415161718192021
            
package com.example;

import java.util.Locale;

public class Main {
    public static void main(String[] args) {
        double amount = 1234567.89;

        // Default locale
        String defaultFormatted = String.format("Default: %, .2f", amount);
        // US locale
        String usFormatted = String.format(Locale.US, "US: %,.2f", amount);
        // Germany locale
        String germanyFormatted = String.format(Locale.GERMANY, "Germany: %,.2f", amount);

        System.out.println(defaultFormatted);
        System.out.println(usFormatted);
        System.out.println(germanyFormatted);
    }
}

When you use String.format() with a specific Locale, the output can change dramatically depending on the conventions of that locale. For example, some countries use a comma (",") as the decimal separator, while others use a period ("."). Similarly, the symbol used to group thousands can be different. Locale-aware formatting ensures that numbers are displayed in a way that users from different regions expect, reducing confusion and errors.

Main.java


              123456789101112131415
            
package com.example;

import java.util.Locale;

public class Main {
    public static void main(String[] args) {
        double value = 9876543.21;

        String us = String.format(Locale.US, "%,.2f", value);
        String germany = String.format(Locale.GERMANY, "%,.2f", value);

        System.out.println("US locale: " + us);
        System.out.println("Germany locale: " + germany);
    }
}

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Section 1. Chapter 5

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Main.java


              123456789101112131415161718192021
            
package com.example;

import java.util.Locale;

public class Main {
    public static void main(String[] args) {
        double amount = 1234567.89;

        // Default locale
        String defaultFormatted = String.format("Default: %, .2f", amount);
        // US locale
        String usFormatted = String.format(Locale.US, "US: %,.2f", amount);
        // Germany locale
        String germanyFormatted = String.format(Locale.GERMANY, "Germany: %,.2f", amount);

        System.out.println(defaultFormatted);
        System.out.println(usFormatted);
        System.out.println(germanyFormatted);
    }
}

Main.java


              123456789101112131415
            
package com.example;

import java.util.Locale;

public class Main {
    public static void main(String[] args) {
        double value = 9876543.21;

        String us = String.format(Locale.US, "%,.2f", value);
        String germany = String.format(Locale.GERMANY, "%,.2f", value);

        System.out.println("US locale: " + us);
        System.out.println("Germany locale: " + germany);
    }
}

Everything was clear?

Thanks for your feedback!

Section 1. Chapter 5

Internationalization with String.format()

1. How does the Locale parameter in String.format() affect the output?

2. Which Locale would you use to format numbers with commas as decimal separators?

3. Why is locale-aware formatting important in international applications?

Internationalization with String.format()

1. How does the Locale parameter in String.format() affect the output?

2. Which Locale would you use to format numbers with commas as decimal separators?

3. Why is locale-aware formatting important in international applications?