Android Debug Bridge, more widely known as ADB, is a core tool for Android. It is included in the Android SDK, in the folder/platform tools. If you go to this folder and call the command adb, you will see on the screen a list of the available options.

With adb, we can perform multiple operations, including displaying devices, taking screenshots, or connecting to and disconnecting from different devices. It is not the purpose of this book to give a thorough review of each operation of a tool, but here, we present a list of the most common and useful functionalities of adb:

Dalvik Debug Monitor Server is also known as DDMS. This utility runs on top of adb, and provides a graphical interface with a big set of functionalities, including thread and heap information, logcat, SMS/call simulation, location data, and more. This is how DDMS looks when it starts:

The screen has different sections:

There are more available options in the DDMS, so let's explore them in detail. First, the section we saw on the top-left side:

Now we want to see how we can deal with thread debugging. The traditional approach of setting breakpoints and waiting until a thread is called will not work well here, since a multithreaded application might have several threads running at the same time and independently of each other. Hence, we want to visualize and access them independently.

Select a process on the left-hand side of the list and click the icon. If now you click in the threads section on the right-hand side, you will see how this section has been updated with information regarding the threads of the current process:

We have learned how to debug threads using DDMS. Now we will learn how to properly analyze the memory heap of an application: that is, the portion of memory where the allocated memory resides. This is very important when it comes to debugging memory leaks.

Let's use a heap dump to track down the problem. Click the icon to dump the HPROF file and choose where you want to save the file. Now run hprof-conv over the file. hprof-conv is an Android utility that converts the .hprof file from the Dalvik format to the J2SE HPROF format, so it can be opened with standard tools. It can be found under /platform-tools. To run it, you need to type the following:

hprof-conv dump.hprof converted-dump.hprof

Now you will have a file that can be understood by some standard tools. In order to read the file, we will use MAT, a standalone version downloadable from http://www.eclipse.org/mat/downloads.php.

MAT is a very complex and powerful tool. Click on File and open Heap Dump...

The allocation tracker is a tool provided by Android that records an app's memory allocations and lists all allocated objects for the profiling cycle with their call stack, size, and allocating code. This goes further than the memory heap and allows us to identify individual pieces of memory being created. It is good to identify places in the code that might be allocating memory inefficiently and to identify objects of the same type that are being allocated and deallocated over a short period of time.

To start using the allocation tracker tool, select your process on the left-hand side, select the Allocation Tracker section in the pane on the right, and then click on the Stop Tracking button. A similar window to the following one will open:

The amount of information can be overwhelming, and there is, therefore, a filter at the bottom where you can specify which information you want to get. If you click on one of the rows, the location of the allocated object will be printed...

In Android 4.0, the Data Usage feature in Settings enables long-term monitoring of how an application uses network resources. Starting with Android 4.0.3, it is possible to monitor an application using network resources in real time. It is possible as well to distinguish traffic sources by applying a tag to network sockets before use.

To display the network usage of an application, select a process from the left-hand side. Then move to the Network Statistics tab and click on the Start button. You can select the tracking speed: every 100, 250, or 500 ms. Then, interact with your application. A similar screen to the following one will be displayed:

The bottom of the screen displays the network information by Tag, and collected by Total. It is possible to see the number of bytes and packages being sent and received in total, as well as a graphical representation of them.

If you haven't done it yet, it is a good idea to set tags on a per-thread basis with the help of the TrafficStats...

The last tab in the DDMS is the so-called Emulator Control. By selecting one of our adb devices and starting it, a tab with some additional options will be shown:

With the emulator control, we can modify our phone network in several ways:

The last section of the DDMS is the System Information tab. Here, it is possible to find out up to three different information categories: the CPU load, memory usage at the current time, and the frame render time (this one is especially important when benchmarking and debugging video games):

We have focused until now on memory, threading, and the system aspects of Android. There is a more visual aspect that can also dramatically improve the performance of our application: the user interface (UI). Android provides a tool called Hierarchy Viewer to debug and optimize any UI designed for Android. Hierarchy Viewer provides a visual representation of the hierarchy of layouts of an application with information about the performance of each node that can be found on the layout. It provides a so-called Pixel Perfect window with magnified information of the display, in case a close look at pixels is required.

To run Hierarchy Viewer, we need first to connect our device or emulator. Note that, for security reasons, only devices running a developer version of the Android system will work with Hierarchy Viewer. When it has been connected, launch the hierarchyviewer program from the /tools directory. If you have not yet set up this directory as part of your system PATH, this...

Hierarchy Viewer provides a powerful profiler to analyze and optimize the application. To proceed with the profiling, click the icon, Profile Node. If the hierarchy of your view is quite large, it might take some time until it is initialized.

At this point, all the views in your hierarchy will get three dots:

Each dot color within a view has a different meaning:

How can...

Systrace is a tool included in the Google SDK to analyze the performance of an application. It captures and displays the execution time from your application on the kernel level (capturing information such as CPU scheduler, application threads, and disk activity). After the analysis has been completed, it generates an HTML file with all the information compiled.

To make it work, click the Systrace button in the DDMS view (). A screen such as the following will appear:

On this screen, we can input a few parameters for Systrace:

When everything...

When we are debugging an Android device, we need to activate developer mode. This mode is hidden by default, and we need to activate it manually if we need to connect the device to ADB or to use some of its options. Android's creators did a good job at hiding this option.

Let's see how we can activate this option to have a better understanding of Android debugging, and how can we play with the different debug configurations.

As mentioned, the developer options in the device are really hidden by default. The purpose for this is very likely to make it only available to advanced users and not to normal users. A casual person will not need to access the features in this section; doing so might options that could harm the device.

In standard ROMs we need to go to the About section, scroll down until we see the Build number entry, and then tap five times in quick succession. A small dialog will be displayed saying that we are now a developer:

Due to custom ROM customization...

At the time of writing, Google released Android Studio 2.2 Preview. This is (as the name suggests) the second major version of Android Studio, and it comes with many fixes, performance improvements, and an awesome tool called Android Instant Run. This tool allows us to perform changes in the code and display them instantly in our device or emulator. This is a priceless feature when we are debugging, since we do not need to recompile the application, start it again, and reconnect it to adb.

To activate this option, we need to go to Preferences, then look for Build, Execution, Deployment | Instant Run. Check Enable Instant Run to hot swap code/resource changes on deploy (default enabled); if you are running the right version of the Gradle plugin, you will be able to activate it:

To run an application, select Run so Android Studio operates normally. Now comes the interesting part: after you have performed edits or modifications on your source code, clicking Run once more will...