new Datum(42)
Error: incompatible types: possible lossy conversion from int to byte
new Datum(42)
<object reference>   (Datum)
Datum d = new Datum(42);
d
<object reference>   (Datum)
d.setTag(50);
d
<object reference>   (Datum)
d.setTag(500);
d.getTag()
500   (int)
datum1
<object reference>   (Datum)
datum1.getTag()
42   (int)
d.setTag(datum1.getTag());
d
Error: cannot find symbol -   variable d