From the Java 1.5 documentation:
If there is an explicit negative subpattern, it serves only to specify the negative prefix and suffix; the number of digits, minimal digits, and other characteristics are all the same as the positive pattern. That means that
"#,##0.0#;(#)"produces precisely the same behavior as"#,##0.0#;(#,##0.0#)".
This is wrong. The negative pattern is, indeed, ignored - but it must be the exact same number of characters as the positive pattern.
But, hey, don't take my word for it. Try it!
import java.text.DecimalFormat;
public class FormatTest {
public static void compareFormats(String goodFormat, String badFormat) {
DecimalFormat good = new DecimalFormat(goodFormat);
DecimalFormat bad = new DecimalFormat(badFormat);
System.out.println("Comparing good <" + goodFormat + "> with the bad format <" + badFormat + ">");
System.out.println("===========================================================================");
System.out.println("Good: prefix=<" + good.getNegativePrefix() + ">; suffix=<" + good.getNegativeSuffix() + ">");
System.out.println(" Bad: prefix=<" + bad.getNegativePrefix() + ">; suffix=<" + bad.getNegativeSuffix() + ">");
System.out.println();
}
public static void main(String[] args) {
compareFormats("#,##0.0#;(#,##0.0#)", "#,##0.0#;(#)");
compareFormats("#,##0.0#;Let''s compare the #,##0.0# of characters", "#,##0.0#;Let''s compare the # of characters");
compareFormats("#,##0.0#;(#,##0.0#)", "#,##0.0#;(01234567)");
compareFormats("#,##0.0#;(#,##0.0#)", "#,##0.0#;(#akasdjf)");
}
}
What do we get after running that?
Comparing good <#,##0.0#;(#,##0.0#)> with the bad format <#,##0.0#;(#)>
===========================================================================
Good: prefix=<(>; suffix=<)>
Bad: prefix=<(>; suffix=<>
Comparing good <#,##0.0#;Let''s compare the #,##0.0# of characters> with the bad format <#,##0.0#;Let''s compare the # of characters>
===========================================================================
Good: prefix=<Let's compare the >; suffix=< of characters>
Bad: prefix=<Let's compare the >; suffix=<racters>
Comparing good <#,##0.0#;(#,##0.0#)> with the bad format <#,##0.0#;(01234567)>
===========================================================================
Good: prefix=<(>; suffix=<)>
Bad: prefix=<(>; suffix=<)>
Comparing good <#,##0.0#;(#,##0.0#)> with the bad format <#,##0.0#;(#akasdjf)>
===========================================================================
Good: prefix=<(>; suffix=<)>
Bad: prefix=<(>; suffix=<)>
Of course. It eats the total number of format characters from the positive pattern from the suffix - if that leaves nothing, then the suffix becomes the empty string.
Great.