## Why is this an issue?

Nested code - blocks of code inside blocks of code - is eventually necessary, but increases complexity. This is why keeping the code as flat as possible, by avoiding unnecessary nesting, is considered a good practice.

Merging `if` statements when possible will decrease the nesting of the code and improve its readability.

Code like

    if (condition1) {
      if (condition2) {             // Noncompliant
        /* ... */
      }
    }

Will be more readable as

    if (condition1 && condition2) { // Compliant
      /* ... */
    }

## How to fix it

If merging the conditions seems to result in a more complex code, extracting the condition or part of it in a named function or variable is a better approach to fix readability.

### Code examples

#### Noncompliant code example

    if (file != null) {
      if (file.isFile() || file.isDirectory()) {  // Noncompliant
        /* ... */
      }
    }

#### Compliant solution

    if (file != null && isFileOrDirectory(file)) { // Compliant
      /* ... */
    }

    private static boolean isFileOrDirectory(File file) {
      return file.isFile() || file.isDirectory();
    }