Auto errors detection in IntelliJ IDEA

Question

I am new to Java programming language and the IntelliJ IDEA 2017.1 IDE.

I just installed the IDE and I activated all the various inspections but the IDE is unable to

Answer 1

If you use a build system (Maven, Gradle, etc.):

Open its panel in IntelliJ, then click the reimport button. For Gradle, this button looks like a sync icon and its hovertext says "Reload All Gradle Projects".

Why it works:

Since the build system is in charge of compiling your code, it knows which files are source code. It would be a waste of computing power to look for missing semicolons in a compiled binary file, so IntelliJ won't try to find errors until it knows the file is source code.

Most build systems, Maven and Gradle included, are also dependency managers. When you write code that uses libraries or depends on a different module, IntelliJ needs to be able to understand the dependency to tell you whether your code makes sense, or whether you made a mistake like forgetting an import statement or passing the wrong type of argument into a library function. When IntelliJ doesn't understand your dependencies, it displays all your uses of imported code in red text.