public static void checkState(boolean expression, Object errorMessage) {
    com.google.common.base.Preconditions.checkState(expression, errorMessage);
  }
public static void checkState ( boolean expression , Object errorMessage ) { com . google . common . base . Preconditions . checkState ( expression , errorMessage ) ; }
Ensures the truth of an expression involving the state of the calling instance, but not
involving any parameters to the calling method.

@param expression a boolean expression
@param errorMessage the exception message to use if the check fails; will be converted to a
string using {@link String#valueOf(Object)}
@throws IllegalStateException if {@code expression} is false