Making the most out of Android Studio Debugger

This is a trick I learnt very recently from a Senior Android Developer at my company and now I feel miserable about all the time I had spent waiting for Gradle builds to test my changes while writing Android Apps.

Here is a typical scenario every android developer would have come across at least once during their development lifetime. You have a List of items that you want to show in a ListView or RecyclerView.

Below is our beloved onBindViewHolder method that binds your model to your views of the RecyclerView.

    @Override
    public void onBindViewHolder(ViewHolder holder, final int position) {

        final String name = values.get(position);
        holder.txtHeader.setText(name);
        holder.txtFooter.setText("Footer: " + name);
    }

Now lets say you wanted to change the text color for every 3rd element in the list. So the code would look something like this

@Override
    public void onBindViewHolder(ViewHolder holder, final int position) {

        final String name = values.get(position);
        holder.txtHeader.setText(name);
        if (position % 3 == 0) {
           holder.txtHeader.setTextColor(Color.GREEN); 
        }
        holder.txtFooter.setText("Footer: " + name);
    }

Then you’d click on Run and wait for build to finish and see your changes, right?

Copied Image from Anand Shekhar Roy’s post on Speeding up your gradle builds.

Now you’d be thinking what other way could we achieve this?

Welcome Android Studio Debugger, yes we need no external plugin or tool to achieve the above task and more over, we won’t even have to build the project, you heard me, we will by pass Gradle :) Here’s how !

Step 1 — We need to define a Run Config

This run config would allow us to launch our app and attach the debugger from android studio to it, alternatively you can also attach it to an already running process by your hand.

Click on Run -> Edit Configurations

On the Top-Left Corner of the Dialog, Click on the + icon and choose Android App

Now give it a name, I like to call it Run-Only, but you can call it anything.

Choose the module which has your app code, in the below screenshot it is called app.

Important step :
In Installation Options, Choose Nothing for Deploy.
In Launch Options, Choose Default Activity
In Before Launch, Remove the Gradle-aware Make task.

So the config should look like this screenshot below

Now you can apply and save this config. It should be selected automatically by Android Studio now, if not just select it from the list.

Now apply a Breakpoint some close before the line you’d like to test a change, in our case we’ll put it where we set the text.

Right Click on the Break Point and Uncheck Suspend. Please write back to me on Twitter, if you have never seen this before, I’d very happy to know I showed you something new :-)

As soon as you uncheck this dialog, you would see this dialog expand with a lot of options.

What we are interested right now is in Evaluate and log. We will write a statement there to test a change in our RecyclerView’s Item. Click on the small blue colored icon next to the dropdown arrow of the Evaluate and log text input box to expand it to a bigger editor and add your testing statement, like this and click Ok and then click on Done.

Now Click on Debug icon with Run-Only Config Selected and see the Magic.

The App Should start from your default activity and you should see the changes applied there, also if you pay close attention to the IDE, on the very bottom you’ll just see one task running that says Launching Activity.

Would love to hear your experiences when you try this trick !! My Twitter Handle is @droidchef

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