Slight differences between aggregation and combination in UML

1 In UML, aggregated graphs are represented as a horizontal line + hollow diamond, and a horizontal line + solid diamond is combined.

2. Aggregation: a special form of association, indicating that the relationship between classes is the relationship between the whole and the part, and some entities can exist independently of the whole.

3 combination: If a detected classification exists, it must depend on the whole.

For example, the order and order items are in a combination. If the order does not exist, the order items do not exist, for example, the mouse, printer, and sound card on the computer,

It can be understood as the aggregation relationship with the computer.