Скачать или смотреть How to Fix the WebView Not Loading URLs in Android Using ViewModel

Learn how to effectively manage `WebView` navigation in your Android application using the `ViewModel` architecture. Discover the common pitfalls and the steps to ensure your URLs load correctly.
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This video is based on the question https://stackoverflow.com/q/63766110/ asked by the user 'Ranjit Singh Shekhawat' ( https://stackoverflow.com/u/8618987/ ) and on the answer https://stackoverflow.com/a/63766188/ provided by the user 'TRK P' ( https://stackoverflow.com/u/5940374/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Understanding the Problem: WebView Not Loading URLs in Android

If you're developing an Android application and using a WebView to load URLs, you might encounter issues when trying to load different URLs based on user actions, such as navigating through a drawer menu. This can lead to frustration, especially when you attempt to utilize the ViewModel architecture for better state management with your WebView. In this guide, we'll explore why your URLs might not be loading and how to fix it.

The Scenario

In your case, you have implemented a WebViewModel class to manage URL loading and are trying to change the URL based on navigation actions in your MainActivity. Here's a breakdown of your key code elements:

The ViewModel Setup

You begin by creating a WebViewModel that includes methods to set and get a URL:

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

The Activity Class

In your MainActivity, you try to change the URL when the user navigates:

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

Observing Changes in the Fragment

From your fragment, you want to observe the URL changes and load the corresponding URL in the WebView:

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

The Root Cause of the Problem

The key issue arises from how you're creating and accessing the WebViewModel instance. In both the MainActivity and your fragment, you are creating separate instances of WebViewModel. When you set a URL in the MainActivity, it doesn't affect the WebViewModel instance in your fragment, leading to the scenario where no URL loads in your WebView.

Solution: Ensure a Single Instance of WebViewModel

To resolve this issue, you'll want to ensure that both your MainActivity and the fragment are referring to the same instance of the WebViewModel. Instead of initializing a WebViewModel in the fragment using ViewModelProviders.of(this), you should obtain the WebViewModel instance from the activity so they both share the same state.

Adjusting Your Implementation

Here's how you can adjust your code to ensure both components use the same WebViewModel instance:

In MainActivity:

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

In your Fragment:

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

This change will ensure both your MainActivity and fragment reference the same WebViewModel instance, thus allowing any URL changes made in the Activity to reflect in the fragment.

Conclusion

By ensuring that your WebViewModel is consistent across your activity and fragment, you'll eliminate the problem of URLs not loading in your WebView. It’s essential in Android development to maintain a centralized state for components that need to share data or state, and using ViewModel correctly is a great way to achieve this.

Now, with these adjustments, your application should successfully load the desired URLs when navigating through your drawer menu. Happy coding!