0.2.15 How to Resolve Feedback System UML Object Diagram Errors

Start by Classifying the Difference

When the Feedback System reports a UML object-diagram problem, first decide what kind of information the message is about.

Most object-diagram differences fit into a small number of categories:

• object identity;
• object type;
• fields;
• values;
• relationships;
• missing or extra elements;
• file/submission problems.

Classifying the message gives you a better starting point than changing the diagram immediately.

Object Identity Problems

Suppose the intended object is:

player1 : Player

but the diagram uses:

jordan : Player

Those names may seem equivalent to a person reading the diagram.

A technical requirement may still expect a particular object identity.

Object identity is part of the model.

If the requirement specifies player1, use the specified identity rather than inventing a replacement because it seems more descriptive.

Object Type Problems

Consider:

player1 : Player

If the diagram instead says:

player1 : Team

the identity may be correct while the type is not.

Separate the two parts of the header.

Ask:

• Which specific object is this?
• What kind of object should it be?

Then correct only the part that is wrong.

Missing or Extra Fields

Suppose the required snapshot needs:

player1 : Player
-------------------------
name = "Jordan"
isAvailable = true

If isAvailable is missing, the diagram cannot communicate that required part of the object's state.

An extra field can also be a problem when it introduces information that does not belong in the current model.

Return to the purpose of the diagram and include the selected fields required for that snapshot.

Incorrect Values

A field can be present and still contain the wrong value.

For example:

isAvailable = false

communicates something different from:

isAvailable = true

Do not correct the field name if the actual problem is the value.

Read feedback precisely enough to distinguish:

wrong field from wrong value.

Relationship Problems

A diagram may contain all the correct objects but connect the wrong pair.

Imagine:

player1 : Player
team1 : Team
match1 : Match

The intended model connects the player to the team and the team to the match.

A line from player1 directly to an unrelated object changes the meaning of the snapshot.

When relationship feedback appears:

1. identify the object at each end of the current line;
2. state in plain language what that line currently means;
3. compare it with the intended relationship;
4. correct the connection in Violet.

Missing Objects

Sometimes a field or relationship appears to be the problem when the actual issue is that an entire object is missing.

For example, you cannot correctly represent:

player1 belongs to team1

if team1 is not present in the diagram.

Before repairing the line, make sure both required object instances exist.

Extra Objects

More objects do not automatically make a diagram better.

If the required snapshot contains one team and two players, adding unrelated coaches, fields, or matches can make the model less focused and may cause feedback errors.

Keep the diagram within the current purpose.

File and Submission Problems

A technically correct diagram can still fail to process if the wrong file is submitted.

If the feedback does not appear to match the diagram on your screen, confirm:

• you saved the diagram;
• you selected the current file;
• the filename is the one you expected;
• the file opens correctly in Violet;
• you did not accidentally submit an exported image or an older copy.

This is why the sequence Edit → Save → Confirm → Submit is so useful.

Avoid Random Trial and Error

Random editing can hide the reason a diagram was wrong.

A stronger correction process is:

Read the message → Identify the model element → Compare it with the requirement → Make one focused revision → Save → Submit again

That keeps the technical feedback connected to the modeling idea.

Read the Corrected Diagram in Plain Language

After a correction, explain the relevant part of the diagram as a sentence.

For example:

player1 is a Player named Jordan, and player1 is related to team1, the Wildcats team.

If the sentence accurately describes the required soccer situation and the UML elements express that same meaning, the model is becoming easier to reason about.

Feedback is most valuable when it helps you understand why the diagram represents the system more accurately after the revision.