How to Debug Android Apps with the Android Studio Debugger

As an Android developer, debugging is an essential part of the development process. It allows us to identify and fix issues within our applications, ensuring a smooth user experience. Thankfully, Android Studio provides a powerful built-in debugger that makes the debugging process more manageable and efficient. In this blog post, we will explore how to debug Android apps with the Android Studio debugger, step-by-step, to help you become a more proficient Android developer.

Step 1: Setting up your Android Project

Before we dive into debugging, you need to set up your Android project in Android Studio. If you don’t have one already, create a new Android project or open an existing one.

Step 2: Launching the Debugger

Once your project is open, connect your Android device to your computer via USB or start an emulator. Now, let’s launch the debugger:

Click on the “Run” menu in Android Studio.
Select “Debug app” or press Shift + F9.
Choose the connected device or running emulator to deploy your app and start the debugger.

Step 3: Setting Breakpoints

A breakpoint is a point in your code where the debugger will pause execution so that you can inspect the application’s state at that particular moment. You can add breakpoints to your code by:

Clicking on the gutter area (left-hand side) of the code editor, next to the line numbers, to set a breakpoint.
Alternatively, you can right-click on the line of code and select “Toggle Breakpoint.”

Step 4: Inspecting Variables and Expressions

When the debugger stops at a breakpoint, you can inspect the values of variables and expressions in the current scope. To do this:

In the “Debug” tab, you will find the “Variables” and “Watches” panes.
Expand the variable or expression you want to inspect, and its value will be displayed.

Step 5: Stepping through the Code

The debugger allows you to step through your code, line by line, to understand the flow and identify potential issues. Here are the primary step commands:

“Step Over” (F8): Executes the current line of code and moves to the next line. If the current line contains a method call, it will not enter the method and will move to the next line in the current method instead.
“Step Into” (F7): Executes the current line of code and enters the method if the current line contains a method call. This allows you to debug inside method calls.
“Step Out” (Shift + F8): Continues execution until the current method returns, and control returns to the calling method.

Step 6: Using Breakpoint Conditions and Logs

Sometimes, you may only want the debugger to stop at a breakpoint under specific conditions. You can add a condition to a breakpoint:

Right-click on the breakpoint and choose “Edit Breakpoint.”
Set the condition using Java expressions, e.g., i == 10 will only stop if the variable i equals 10.

Additionally, you can add log messages to track the flow of your application:

Use Log.d("Tag", "Message") to add log messages in your code.
View the logcat output in the “Logcat” tab in Android Studio.

Step 7: Debugging Native Code

If your Android app uses native code (C/C++), you can also debug it with Android Studio. To do this:

Set a breakpoint in your native code as you would in Java/Kotlin.
Click on the “Attach Debugger to Android Process” icon in the debug toolbar.
Select the process related to your app from the list to attach the debugger.

Step 8: Using the Debugger’s Watches

In addition to inspecting variables in the “Variables” pane, Android Studio’s debugger allows you to add watches. A watch is an expression you want to evaluate whenever the program stops at a breakpoint. It can be handy for monitoring specific variables or complex expressions.

To add a watch:

Open the “Watches” pane in the “Debug” tab.
Click the “Add watch” button (plus icon) and enter the expression you want to evaluate.

Step 9: Conditional Breakpoints

Conditional breakpoints are another powerful feature of the Android Studio debugger. Rather than stopping every time a breakpoint is reached, you can set conditions for when the breakpoint should be triggered.

To add a conditional breakpoint:

Right-click on the breakpoint in the code editor.
Choose “Edit Breakpoint” and enter the condition in the provided text field.

Step 10: Remote Debugging

Sometimes, you might encounter bugs that only occur in specific situations, like on a particular device or under certain network conditions. Android Studio allows remote debugging to connect your development environment to a physical device or emulator running on a remote machine.

To enable remote debugging:

Connect your Android device to the remote machine via USB.
On the remote machine, run the app with debug mode enabled.
On your development machine, click “Run” > “Attach debugger to Android process.”
Select the appropriate process from the list to attach the debugger.

Step 11: Profiling Tools

Android Studio provides powerful profiling tools to help you optimize your app’s performance and memory usage. Profiling allows you to analyze the app’s CPU usage, memory allocation, and network activity during runtime.

To access the profiling tools:

Click on the “Profile” tab at the bottom of the Android Studio window.
Choose the appropriate profiling tool for your needs, such as “CPU Profiler,” “Memory Profiler,” or “Network Profiler.”

Step 12: Exception Breakpoints

Sometimes, your app might crash or behave unexpectedly due to uncaught exceptions. You can set up exception breakpoints to stop the debugger whenever an exception occurs, even if it would be caught and handled in the code.

To add an exception breakpoint:

Open the “Breakpoints” tab in the “Debug” pane.
Click the “Add Exception Breakpoint” button (plus icon).
Select the type of exception you want to catch.

Mastering the Android Studio debugger is crucial for becoming an efficient Android developer. By using breakpoints, watches, conditional breakpoints, and logs, you can gain deep insights into your app’s behavior and resolve issues with confidence. Additionally, remote debugging and profiling tools can help you tackle real-world scenarios and optimize your app’s performance.

Debugging is not only about fixing problems but also about understanding your code and learning from it. Embrace the debugging process as an opportunity to become a better developer and create more robust and polished Android applications. Happy coding!