What is the best way to convert an object I get from a database to String in Java? For example, I have a field which returns a BigDecimal. How do I convert it to String, while keeping it as null (primitive), if it comes back null? I was using String.valueOf(obj), but this actually transforms it to the String representation "null".
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3 Answers
As you've noticed you get the string "null" instead of an actual null value. This is by design:
Returns:
if the argument is null, then a string equal to "null"; otherwise, the value of obj.toString() is returned.
That said, you could just check if it's null before converting it:
import java.math.BigDecimal;
class Main
{
public static void main (String[] args)
{
BigDecimal foo = new BigDecimal(1.0);
BigDecimal bar = null;
// if the value isn't NULL, use String.valueOf, else use NULL
String fooString = foo != null ? String.valueOf(foo) : null;
String barString = bar != null ? String.valueOf(bar) : null;
System.out.println(fooString == null ? "REALNULL" : "\"" + fooString + "\"");
System.out.println(barString == null ? "REALNULL" : "\"" + barString + "\"");
}
}
Output:
"1"
REALNULL
2 Comments
Tiberiu Dorian Moşescu
thanks, I did just this. It just seemed a bit too long to write at first, but ok
h2ooooooo
@TiberiuDorianMoşescu You're welcome. If it's annoying to keep writing it, simply make your own util class and use
StringUtils.valueOfNull(foo).this is something you can do for converting those values into string values.
decimal dValue = 59.24;
String sValue = dValue+"";
Comments
I think casting the Object to a String or indeed using String.valueOf(obj) would work, but just do a check if the value isn't null, like:
if(obj == null) {
//Do something
}
else {
String s = (String) obj;
}
1 Comment
Tiberiu Dorian Moşescu
casting will throw a classCastException or sth similar
