public class PMD_FN_Demo {

    /**
     * Scenario A: Standard index traversal (PMD reports this correctly)
     * Violation: "This for loop can be replaced by a foreach loop"
     */
    public void testTruePositive(long[] counts) {
        double total = 0;
        for (int i = 0; i < counts.length; i++) {// <-reported(TP)
            total += counts[i];
        }
    }

    /**
     * Scenario B: Array length assigned to a pre-declared variable (FN - PMD misses this)
     * Even though it is semantically identical to Scenario A, no violation is reported.
     */
    public void testFalseNegative(long[] counts) {
        double total = 0;
        // Assigning array length to a pre-declared local variable
        int len = counts.length; 
        for (int i = 0; i < len; i++) {//<-should report (FN)
            total += counts[i];
        }
 
    }
}