Swing GUI and EDT | Dataford Interview Questions

What happens if you update a Swing GUI outside of the event dispatch thread?

Asked in the hiring manager / panel interview stage. Implement a validator that identifies unsafe Swing operations. An operation is unsafe when a direct component mutation occurs on a non-EDT thread. repaint, revalidate, and operations already running on the EDT are safe.

Input and Output

Implement validate_swing_updates(operations). Each operation is a dictionary with thread and action strings. Return the zero-based indices of unsafe operations in input order.

Constraints

1 <= len(operations) <= 10^5
Each operation contains exactly the keys thread and action
thread is either EDT or worker
action is repaint, revalidate, or a direct component mutation

Function Signature

def validate_swing_updates(operations):

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Problem