Empty statements, i.e. ;, are usually introduced by mistake, for example because:

Noncompliant Code Example

void doSomething() {
  ;                                                       // Noncompliant - was used as a kind of TODO marker
}

void doSomethingElse() {
  System.out.println("Hello, world!");;                     // Noncompliant - double ;
  ...
  for (int i = 0; i < 3; System.out.println(i), i++);       // Noncompliant - Rarely, they are used on purpose as the body of a loop. It is a bad practice to have side-effects outside of the loop body
  ...
}

Compliant Solution

void doSomething() {}

void doSomethingElse() {
  System.out.println("Hello, world!");
  ...
  for (int i = 0; i < 3; i++){
    System.out.println(i);
  }
  ...
}

See