How to Ensure Functions Execute Sequentially in Flutter: Flutter Function Calls Made Easy

Learn how to properly execute functions in Flutter by ensuring that a function only runs after the completion of a previous one. This guide focuses on using async functions to manage your code effectively.
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How to Ensure Functions Execute Sequentially in Flutter

In the world of Flutter programming, you may encounter situations where you need to call multiple functions in a specific order. This is particularly true when you want one function to execute only after another has completed. If you ever found yourself in a situation where functions run simultaneously instead of sequentially, you're not alone. In this post, we'll tackle the problem and explore a solution that leverages asynchronous programming in Dart.

The Problem

Imagine you are developing a Flutter application that requires user interaction through a pop-up dialog box to add a group. After the user closes this dialog, you want to refresh the screen to reflect the updated state. However, if you execute these functions simultaneously, you risk refreshing the page before the user interaction has fully completed. Take a look at the initial implementation:

[[See Video to Reveal this Text or Code Snippet]]

In this code snippet, popUpForGroup() runs, but the subsequent function calls execute immediately after, without waiting for any user action to complete. This can lead to unexpected behavior in your app. So, how can we make sure that refreshPage() only runs after popUpForGroup() is finished?

The Solution

To resolve this issue, we need to make use of asynchronous programming in Dart. The key is to identify the function that needs to wait for completion and turn it into an async function. Here are the steps to modify your code accordingly:

Step 1: Modify the popUpForGroup Function

You'll need to make popUpForGroup an asynchronous function. This means that it will return a Future, indicating that it will complete its work at some point in the future.

Here's how you can do that:

[[See Video to Reveal this Text or Code Snippet]]

Step 2: Update the onPressed Callback

Now, modify the onPressed callback to use the async keyword. This allows you to use the await keyword before calling popUpForGroup, which makes the function execution pause until popUpForGroup is finished. Here’s what the updated code will look like:

[[See Video to Reveal this Text or Code Snippet]]

Explanation of Changes

async: The async keyword marks the function as asynchronous, allowing it to perform tasks that take time (like showing a dialog) without freezing the app.

await: Using await before the popUpForGroup() call tells Dart to wait for this function to complete before moving on to the next line of code. Thus, refreshPage() will only execute after the pop-up action is finished.

Advantages of This Approach

Control Over Execution: By arranging your function calls, you have better control over the flow of your application.

User Experience: Users will see the updated state of your application only after their interaction is fully processed, which is crucial for any app focusing on user engagement.

Conclusion

In Flutter, ensuring that functions execute in the right order can prevent bugs and enhance the functionality of your application. By transforming your functions to be asynchronous and using the await keyword, you can effectively manage the execution flow and improve the overall experience for your users. Give it a try and watch your Flutter application behave more predictably!