Based on what a Type is, dispatch it to the corresponding visit* method. By default, no recursion is done for type arguments or type bounds. But subclasses can opt to do recursion by calling visit for any Type while visitation is in progress. For example, this can be used to reject wildcards or type variables contained in a type as in:

new TypeVisitor() {
  protected void visitParameterizedType(ParameterizedType t) {
    visit(t.getOwnerType());
    visit(t.getActualTypeArguments());
  }
  protected void visitGenericArrayType(GenericArrayType t) {
    visit(t.getGenericComponentType());
  }
  protected void visitTypeVariable(TypeVariable<?> t) {
    throw new IllegalArgumentException("Cannot contain type variable.");
  }
  protected void visitWildcardType(WildcardType t) {
    throw new IllegalArgumentException("Cannot contain wildcard type.");
  }
}.visit(type);

One Type is visited at most once. The second time the same type is visited, it's ignored by visit. This avoids infinite recursion caused by recursive type bounds.

This class is not thread safe.