Ytdyklly

I was working in a project and I finished all my tasks.

Another dev started to work in the new tasks.
Now I have downloaded the project and its with some build errors on it.

How can I handle with this?

I should think that the version control is enough to the manager or another one sees who screwed up the project?

Or I should talk to him, asking about the changes he did?

I'm new in this company, and he is too. But he seems to be less skilled than me.

EDIT

I talked to him about the build error and he told me he knows about it but he does not seems to care, because its building and running normally even been all classes red (Android studio things).

Anyway, I have told him that I will make a change about it and I fixed and committed.

You should definitely talk to him about it. Maybe he didn't fully commit all his code/changes, or maybe he committed on accident.

If he did commit everything & was fully aware of doing so, you should ask him about the errors & maybe even offer to help fixing them if he doesn't know how to do so himself.

You can always go straight to your manager if it turns out he just doesn't care about the quality of his code or if you feel like his incompetence hinders you from doing your job.

Calmly talking to him about it should be the first step, you're colleagues after all.

I should think that the version control is enough to the manager or another one sees who screwed up the project?

Perhaps, but that should not be your main concern. You do not want to play the blame game; that will not improve working relations, and certainly won't help to fix the problem.

Or I should talk to him, asking about the changes he did?

Talk to him. Don't blame him. Point out why it's broken, and then ask "how can we fix this?" Emphasize that all you care about is bringing the project to a good end.

I'm new in this company, and he is too. But he seems to be less skilled than me.

So what? It's not a competition. There will be others who are more skilled than you.

Talk to him. Don't run to the manager whenever something doesn't build.

Are you sure your environment is set up correctly? Is there any chance you could be missing something? Double check before approaching your colleague. When you do approach him, I suggest framing the question as a request for help getting the project building.

Something along the lines of "I pulled the repo down but it doesn't build. I'm not sure if I set something up wrong, could you help me?"

This will give him the opportunity to see that his change broke the code. You are both new so it is valid to ask for his help setting up regardless! Give him an opportunity to fix it himself first, before escalating something that happens in every software development environment.

If you have version control, which I hope you have, you should be able to see what changes he made. I suggest you talk to your supervisor about setting up some sort of a code review system in the future.

How can I handle with this?

Implement a Pull Request (or whatever you call it) workflow that will allow another dev to review changes before they are added

Developers, even seasoned ones break the build. It sounds like you are not the tech lead. Step up and show the tech lead you'll take point on implementing the (much needed) process.

Go talk to him 1 on 1 about the changes. See if this is a configuration issue on your part. If it is, problem solved.

If not, look at how you can use a workflow to stop this from happening again.

After reviewing how to turn on reviews and auto-builds in your current system, approach the tech lead. Say something like

I've noticed that sometimes people check in changes that break the system, and if we turn on PR reviews, that should go down significantly. We can also build the system every time someone checks in, which should cut down on that too.

Hopefully the tech lead will be overjoyed someone wants to step up and do this. If they vehemently hate the idea, run for your life.

Step 1: Talk to him. Mention that the build is broken, and the last commit on it was his commit, so ask him what happened (it's important to not say "you broke the build!" because a) that's accusatory and b) perhaps his change wasn't actually the change that broke the build, e.g. maybe it was a configuration change, or maybe you forgot about a change you yourself made, etc, in which case you come off looking very abrasive and accusatory).

Step 2: If he is receptive to your statement, work with him to fix it and if he doesn't understand what went wrong, explain it to him. Explaining it to him will teach him how not to make the same mistake again. That's called mentorship and is very important among colleagues, particularly more experienced ones (towards less experienced ones). You will be looked on highly by your superiors if you can productively engage in mentorship.

Step 2a: In the extremely unlikely case that he is not receptive to your statement, then it's time to fight: Double-check your work to make absolutely sure he broke the build, then go to your manager and show him that the build is broken and that the colleague did it. Then it's the manager's problem, not yours, and that's where your responsibility ends.

Step 3: Next time this particular colleague breaks the build, rinse and repeat. If it happens a number of times and you feel it is a pattern of irresponsibility, then you can go to your manager and say "Hey Bob, you know Joe has broken the build a number of times and I've tried talking to him about it, but it just seems he doesn't care, mind talking to him about it?" or something like that. Don't go in aggressive or accusatory; make the issue about breaking the build, not about the colleague. Your manager will decide what the best course of action is from there.