[java] New rule IdenticalConditionalBranches

[zbynek]

Describe the PR

Add a rule for finding useless ifs and ternary expressions.

Proposed Rule Name: IdenticalConditionalBranches

Proposed Category: Error Prone

Description:
Conditional statement that does the same thing when the condition is true and false
is either incorrect (one of the branches should be changed) or redundant
(can be replaced by one of its branches).

Code Sample:

class Test {
    int method1() {
        if (Math.random() > 0.5) {
            return 1;
        } else {
            return 1;
        }
    }
    int method2() {
        return Math.random() > 0.5 ? 1 : 1;
    }
}

Possible Properties: none

Related issues

• Fix #

Ready?

• Added unit tests for fixed bug/feature
• Passing all unit tests
• Complete build ./mvnw clean verify passes (checked automatically by github actions)
• Added (in-code) documentation (if needed)

[pmd-actions-helper]

Documentation Preview

Compared to main:
This changeset changes 0 violations,
introduces 237 new violations, 0 new errors and 0 new configuration errors,
removes 0 violations, 0 errors and 0 configuration errors.

Regression Tester Report

(comment created at 2025-10-24 10:46:18+00:00 for ffa480c)

[oowekyala]

Good idea, thank you

I wonder if another name would be more appropriate. Maybe "IdenticalIfStatementBranches". For one I'm not a fan of the word "useless" as it feels a bit rough, but that's secondary. The main reason is that "UselessCondition" sounds a bit vague and could be confused with a rule that checks conditions that are always true/false for instance. Also if-statements are not the only ones that have conditions (see loops), but they're the only ones checked by this rule.

[adangel]

Thanks!

I'll update the release notes and merge it for 7.18.0.