Debugging

Developing software can sometimes be extremely frustrating. You maybe have an error and you dont understand why. Debugging is the process of fixing error systematically. Developers spend probably 80% on debugging and 20% on actual development.

Lucikly IntelliJ has some tools that can help us with the process!

Watch this video as support 👇

https://youtu.be/o_zc6tiyH2w

IntelliJ debugger

The Debugger is a tool that can help understanding your code. It works by indicating a place or multiple places in the code you want the code to stop and figure out what the values of our variables are. These places are called breakpoints.

Setting a breakpoint

To set a breakpoint in IntelliJ click to the right of the line number. Now a red dot should appear

Set a breakpoint

Starting the debugger

Next to the green play icon that runs your code, there is a small little green bug. Clicking this will start the debugger.

Start debugging

Working with the debugger

Now the debugger is running and there are a couple of things to notice:

• The first thing is that all the variables in the code has their value displayed inline to the right the variable. That is super helpful!

• The second thing to see is that in the bottom where the console normally is there is a new window. To the right of that window is the list of the variables and their values.

• The third thing to see when hovering any expressions the value of that expression is shown!

• The fourth thing is that the line that is highlighted with blue is the current debugger line. That is how far the debugger has reached

Debugger variable values

Controlling the debugger

The highlighted area in the image below shows the controls of the debugger. Let's go through them below

CleanShot 2021-06-09 at 15.43.03@2x

• Step into - Will either go to the next line that is executed or go into a method if the current line is a method call

• Step Over - If the current line is a method call you can step over that method call (not debugging inside that method)

• Force step into - If there is a method call no matter the type of method call it will step into that

• Step out - Will step out of the method that the debugger is in

• Step to cursor - Will step into where the cursor is

With these tools you can hopefully easier debug your program to find out what is going wrong.