IntelliJ - show where errors are

For IntelliJ 2017:

Use "Problem" tool window to see all errors. This window appears in bottom/side tabs when you enable "automatic" build/make as mentioned by @pavan above (https://stackoverflow.com/a/45556424/828062).

To access this Problems panel, you must set your project to build automatically. Check the box for Preferences/Settings > Build, Execution, Deployment > Compiler > Build project automatically.

Frankly the errors are really hard to see, especially if only one character is "underwaved" in a sea of Java code. I used the instructions above to make the background an orangey-red color and things are much more obvious.

In IntelliJ Idea 2019 you can find scope "Problems" under the "Project" view. Default scope is "Project".

In my case, I unknowingly unchecked 'Error Stripe Mark' option (Idea 2018.2: Settings > Editor > Color Scheme > General and expand `Error and Warnings' & click 'Error').

Fix is to check 'Error Stripe Mark' option of 'Error' (as highlighted in the below image). Now you will see the error marks in scrollbar area.

In my case, IntelliJ was simply in power safe mode

Do you have a yellow icon like this [_] at the bottom of the main window? It is a "type-aware highlighting" switch which could be disabled accidentally. You should re-enable it by clicking on the icon.

In the intellij hit ctrl+alt+shift+s and go to global libraries and click on plus icon to add the java libraries this will solve your problem. now you will see the errors coming up

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This is the solution I found:

0. Open IntelliJ Setting (Crtl + Shift + A);
1. Click in "Editor";
2. Click in "Color Scheme" + the Programming Language (inside "Color Scheme");
3. Select "Analysis Error";
4. Select "Error stripe mark" + Add the Color desired