Saving Variable Values in Flutter: Use SharedPreferences for Persistence

Learn how to save and persist variable values in Flutter applications using SharedPreferences. This guide will cover the basics of storing data to ensure your variables hold their value even after app restarts.
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Saving Variable Values in Flutter: Use SharedPreferences for Persistence

If you've been developing in Flutter, you may have encountered a common challenge: how to save the value of a variable so that it persists even after you restart the application. For instance, if you have a boolean variable (let's say bool X = false;), and then, due to a user action such as tapping a button, you change it to true, the new value disappears when you close and reopen the app.

In this guide, we'll delve into a straightforward solution for saving variable values in Flutter by using the SharedPreferences package. This tool allows you to easily store data locally on the device, making your application more robust and user-friendly.

Understanding the Problem

Let's break it down with an example. Suppose you have the following snippet in your Flutter application:

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When the button is pressed, the value of W1_D1_workout1 changes to true. However, if you restart the app, the value resets to its initial state: false. This is because local variables are stored in memory and do not retain their values once the app is closed.

The Solution: Using SharedPreferences

To solve this issue, you can use the SharedPreferences package, which provides a way to store and retrieve key-value pairs locally. Here's how you can implement it step-by-step:

Step 1: Add Dependency

First, you'll need to add the shared_preferences dependency to your pubspec.yaml file:

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Step 2: Import the Package

In the Dart file where you want to save and retrieve the variable, make sure to import the package at the top:

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Step 3: Save the Value

When you want to save the value of W1_D1_workout1, modify your button's onPressed function like this:

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Step 4: Retrieve the Value

Finally, when your app starts, you’ll want to check if there’s a saved value and retrieve it. You can do this in your widget's initState or just before using the variable:

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Conclusion

By incorporating SharedPreferences into your Flutter application, you can easily save and retrieve variable values, ensuring that user actions result in persistent changes. This leads to a smoother user experience and makes your application feel more responsive.

Give it a try in your project and enjoy the benefits of persistent variable storage! If you have any questions, comments, or additional tips, feel free to drop them below. Good luck! ❤️

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