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import org.checkerframework.checker.nullness.qual.*;
class TestPolyNull {
@PolyNull String identity(@PolyNull String str) {
return str;
}
void test1() {
identity(null);
}
void test2() {
identity((@Nullable String) null);
}
public static @PolyNull String[] typeArray(@PolyNull Object[] seq, @Nullable String nullable) {
@SuppressWarnings("nullness") // ignore array initialization here.
@PolyNull String[] retval = new @Nullable String[seq.length];
for (int i = 0; i < seq.length; i++) {
if (seq[i] == null) {
// null can be assigned into the PolyNull array, because we
// performed a test on seq and know that it is nullable.
retval[i] = null;
// and so can something that is nullable
retval[i] = nullable;
// One can always add a dummy value: nonnull is the bottom
// type and legal for any instantiation of PolyNull.
retval[i] = "dummy";
} else {
retval[i] = seq[i].getClass().toString();
// :: error: (assignment.type.incompatible)
retval[i] = null;
// :: error: (assignment.type.incompatible)
retval[i] = nullable;
}
}
return retval;
}
public static @PolyNull String identity2(@PolyNull String a) {
// TODO: it would be nice, if this code type-checks (just like identity and identity3),
// but currently a technical limitation in the flow analysis prevents this
// :: error: (return.type.incompatible)
return (a == null) ? null : a;
}
public static @PolyNull String identity3(@PolyNull String a) {
if (a == null) {
return null;
}
return a;
}
}
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