Sonar interprets fine condition as gratuitous

SonarQube for IDE Eclipse
,
1

I am using SonarLint 4.2 with Eclipse.

Here is a sample snippet, where squid:S2589 detected unreasonably:

import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;

public class feladat {

    private static final long MAX_NORMAL = 800;
    
    
    public static void main(String[] args) {
        int count;
        List<Flooding> floodings = new ArrayList<>();
        Flooding bestFlooding = null;
        long bestTail = -1;
        
        Scanner scanner = new Scanner(System.in);
        count = scanner.nextInt();
        Flooding currentFlooding = null;
        for (int n = 1; n <= count; n++) {
            long value = scanner.nextLong();
            boolean isFlooding = value > MAX_NORMAL;
            if (isFlooding) {
                if (currentFlooding == null) {
                    currentFlooding = new Flooding(n, value);
                    floodings.add(currentFlooding);
                } else {
                    currentFlooding.add(n, value);
                }
            } else if (currentFlooding != null) {
                long tail = currentFlooding.getTail();
                if (bestFlooding == null || tail < bestTail) { // NOSONAR is not gratuitous!
                    bestFlooding = currentFlooding;
                    bestTail = tail;
                }
                currentFlooding = null;
            }
        }
        scanner.close();

        // etc.
    }
    
    private static class Flooding {
        
        final int startLocation;
        
        int maxLocation = -1;
        
        long maxValue = -1;
        
        int endLocation = -1;
        
        
        Flooding(int startLocation, long startValue) {
            this.startLocation = startLocation;
            this.maxLocation = startLocation;
            this.maxValue = startValue;
            this.endLocation = startLocation;
        }
        
        void add(int location, long value) {
            this.endLocation = location;
            if (value > this.maxValue) {
                this.maxLocation = location;
                this.maxValue = value;
            }
        }
        
        int getTail() {
            return endLocation - maxLocation;
        }
        
    }
    
}

NOSONAR should not be necessary.

2

Hello @davidsusu,

Thank you for reporting this! It is indeed a false positive, which seems to be related to this existing ticket: https://jira.sonarsource.com/browse/SONARJAVA-2523 and which is a current limitation of our symbolic execution engine.

We hope to address this at some point in the future but in the meantime if this FP is causing too much inconvenience in your project, you can also disable the rule in your SonarLint configuration.

Guillaume