#1104 "Null passed for nonnull parameter" false positive

[Lukas Eder]

Consider this piece of Java code:

--------------------------------------------------------
import java.math.BigInteger;

public class Test {
void x() {
BigInteger i = BigInteger.ZERO;

if (i == null) {
i = BigInteger.ZERO;
} else {
i = BigInteger.ZERO;
}

System.out.println(new BigInteger("1").add(i));
^^^^ FindVugs detects a bug here
}
}
--------------------------------------------------------

The detected bug reads

> Bug: Null passed for nonnull parameter of java.math.BigInteger.add(BigInteger) in Test.x()

The actual problem, however, is the useless null check, as BigInteger.ZERO can never be null.

[William Pugh]

OK, to fix this I had to tell findBugs that BigDecimal.ZERO is always nonnull.

Without knowing that, FindBugs was actually being fairly clever to report the warning correctly.

[Lukas Eder]

Thanks for fixing this. Was it only related to BigInteger.ZERO? Because I feel that possibly, all static final values could be affected...

[William Pugh]

If the code had used field Foo.BAR, then you would want a bug reported here. It is only a false positive because BigInteger.ZERO is known to be non null.