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Discover a straightforward method to pass static variables between activities in Android using Java. Learn how to manage shared data across your app easily!
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Passing a Variable from an Activity to a Class in Android

As a beginner in Android development, you may find it essential to share data between various components of your app. A common scenario involves passing variables from one Activity to another, particularly when you want to share constant values that will be accessed in multiple classes. If you've had trouble with methods like Shared Preferences to achieve this, fear not! In this post, we'll show you an effective way to manage static variables that can be accessed throughout your application.

The Problem: Passing Data Between Activities

Imagine you have a list of buttons in your app, and when a user clicks on one button, you want to open a new activity while passing a specific variable, such as a URL. You attempted to use shared preferences but faced difficulties.

In your code, you declared a static variable in class AppConstant like this:

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

The challenge is to pass the url value effectively so it can be used as BASE_URL across various classes. Let’s look into a solution that doesn’t rely on shared preferences but allows seamless data sharing.

The Solution: Using an Interface with a HashMap

Instead of using shared preferences, you can leverage a more straightforward method through an interface and a HashMap. Here’s how you can implement this solution:

Step 1: Create an Interface

Create a separate Java file for your interface, which can be named Ext.java.

Define a public abstract interface like this:

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

This myHash variable will be instantiated when the app launches and will persist throughout the application's lifecycle.

Step 2: Store Data in the HashMap

When the user clicks a button in your original activity, you can add the desired URL value to the HashMap. Here’s how:

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

Step 3: Access the Data from Another Activity

In the new activity where you want to use the passed URL, you can easily retrieve the value stored in the HashMap as follows:

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

By following this method, you ensure that your BASE_URL is accessible from any part of your application as long as the app is running, and you maintain the static nature of the variable.

Conclusion

This approach to passing variables between activities in Android using Java simplifies data sharing within your application. Instead of struggling with shared preferences, you can adopt this clear and concise method using an interface and a dynamic HashMap.

By defining a public interface, you can store and retrieve your variables easily, ensuring that your app runs smoothly and efficiently.

Now, whenever you need to pass static data like a URL across activities, you’ll have a reliable solution at your fingertips! Happy coding!