Hey there! Let's clear up this confusion around UML association arrows—your initial hunch is actually on the right track, but let's refine it to be precise:

The arrow on a UML association represents navigability, which directly translates to "which class can access the other". So if you see an arrow pointing from Class1 to Class2, that means:

• Class1 can hold references to Class2 instances (like having a member variable of type Class2)
• Class1 can call methods on Class2, access its properties, or use its functionality in any way
• By default, without a reverse arrow, Class2 cannot directly access Class1 instances

Let's use a real-world example to make this concrete:

• Suppose we have User and Profile classes. If the association arrow goes from User to Profile, that means a User can retrieve their own Profile (e.g., user.getProfile()), but a Profile can't automatically find the User it belongs to unless we add a reverse arrow or explicitly design that relationship.

A few key clarifications to avoid common mix-ups:

• Don't confuse association arrows with dependency relationships (the dashed arrow): dependencies are temporary (like a method accepting a Class2 parameter), while associations represent long-term, structural relationships.
• If an association has no arrow at all, it's assumed to be bidirectional navigable—both classes can access each other's instances.
• While you might see double arrows sometimes, they're redundant; a无箭头 association already implies bidirectional access.

To boil it down to your original question: Yes, that arrow does mean Class1 uses/accesses Class2's content—navigability is exactly that ability to reach and use the other class's members.

内容的提问来源于stack exchange，提问作者john