LowFile-scopeJava Plug & play

Validate parameter types before casting

Use instanceof/pattern matching and guard before casts; avoid ClassCastException.

Why this matters

Ensures safe handling of heterogeneous data.

Side-by-side examples engineers can pattern-match during review.

Avoid

Map m = (Map) obj; String v = (String) m.get("v");

Prefer

if (obj instanceof Map<?,?> m) { Object v = m.get("v"); if (v instanceof String s) { /* use s */ } }

Bad

(List<String>) obj

Good

if (obj instanceof List<?> list) { /* ... */ }

From the same buckets as this rule.

Critical
Avoid equality operators in loop termination conditions
Check if loops use equality operators (== or !=) in termination conditions. These can lead to infinite loops if the condition is never met exactly. Instead, use relational operators like < or > for safer loop termination.
error-handlingreadability-refactor
Critical
Avoid Returning Null in Non-Async Task Methods
Returning null from a Task or Task<T> method causes a NullReferenceException if awaited. Use Task.CompletedTask or Task.FromResult<T>(null) instead.
error-handlingreadability-refactor+1
Critical
Avoid Using Boolean Expressions in `except` Statements
Detect `except` clauses that use `or` or `and` to catch multiple exceptions. This does not work as intended. Recommend using a tuple of exceptions instead.
error-handlingstack-python