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Never use assertions to validate parameters of {{public}} methods. According to the Java Language Specification \[[JLS 2005|AA. Bibliography#JLS 05]\], Section 14.10 "The {{assert}} Statement":

Along similar lines, assertions should not be used for argument-checking in public methods. Argument-checking is typically part of the contract of a method, and this contract must be upheld whether assertions are enabled or disabled.

Another problem with using assertions for argument checking is that erroneous arguments should result in an appropriate runtime exception (such as IllegalArgumentException, IndexOutOfBoundsException or NullPointerException). An assertion failure will not throw an appropriate exception.

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This noncompliant code example uses assertions to validate arguments of a public method.

public static int AbsAdd(int x, int y) {
  assert x != Integer.MIN_VALUE;
  assert y != Integer.MIN_VALUE;
  int absX = Math.abs(x);
  int absY = Math.abs(y);
  assert (absX <= Integer.MAX_VALUE - absY);
  return absX + absY;
}

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