How to change language of app when user selects language?

How to Change the App Language Based on User Selection

Changing the language of an Android application based on the user's selection is a common requirement for localization and internationalization. This article demonstrates how to achieve this by providing a method that accepts the desired language locale, updates the application's locale, and refreshes the current activity to reflect the language change.

Implementation Steps:

1. Create a method called setLocale that accepts a language locale as a string parameter (e.g., "en" for English, "hi" for Hindi).
2. Inside the setLocale method:
• Create a new Locale object using the language locale passed as a parameter.
• Get the application's resources and display metrics.
• Create a new Configuration object and set its locale to the newly created Locale object.
• Update the application's resources with the new configuration.
3. Create an intent to refresh the current activity and start it.
4. Finish the current activity to ensure the changes take effect.

Java Code:

public void setLocale(String lang) {
    Locale myLocale = new Locale(lang);
    Resources res = getResources();
    DisplayMetrics dm = res.getDisplayMetrics();
    Configuration conf = res.getConfiguration();
    conf.locale = myLocale;
    res.updateConfiguration(conf, dm);
    Intent refresh = new Intent(this, AndroidLocalize.class);
    finish();
    startActivity(refresh);
}

Make sure to import the necessary packages:

import java.util.Locale;
import android.os.Bundle;
import android.app.Activity;
import android.content.Intent;
import android.content.res.Configuration;
import android.content.res.Resources;
import android.util.DisplayMetrics;

Add the following line to your activity in the manifest:

android:configChanges="locale|orientation"

Alternative Approaches:

• You can override the onConfigurationChanged method to handle locale changes without restarting the activity. However, this may not be suitable for all scenarios.
• You can use a custom ContextWrapper class to change the locale for the entire application. This approach allows you to set the locale once and have it applied to all activities and fragments within your app.
• With the introduction of AndroidX Appcompat 1.6.0-alpha04 and later, there is a new, improved implementation for in-app language pickers. This implementation uses the latest Android APIs and is more efficient than the custom implementations mentioned above.

Additional Considerations:

• Ensure that the languages you want to support are included in your app's build.gradle file under the resConfigs設定。
• Rebooting the activity can be a performance-intensive operation. To avoid unnecessary restarts, consider checking if the desired locale is already set before calling the setLocale method.
• Changing the app's language may affect the layout and other UI elements. Make sure to test your app thoroughly to ensure it functions correctly in all supported languages.

In conclusion, there are several techniques available to change the language of an Android application based on user preference. By following the steps outlined in this article, you can provide a seamless localized experience for your users, regardless of their language.