Hi Naoto, Sorry for the off thread reply. I didn't have the mail replies setup on the list and I seem to be unable to add a in-reply-to header via web email.
> Although the error message may be confusing, 'c' conversion cannot be > used for a String argument (like in your example). It simply converts > numeric value into a single character, thus no need for output > "precision." I am not the designer of the class, so might be wrong. Yes I totally missed that. I dug up the relevant source: https://github.com/openjdk/jdk/blob/350303d4f0c71f77fa784a92d13522a380e3b2fe/src/java.base/share/classes/java/util/Formatter.java#L3006 https://github.com/openjdk/jdk/blob/c709e1cbf030e7129fa34815b150097ba6f6840c/test/jdk/java/util/Formatter/Basic-X.java.template#L432 So this code doesn't deal with CharSequence and therefore the precision is implicitly one. With the exception if null getting converted to 4 chars. Is it worth me filing an RFE to allow 'c' to accept a CharSequence and allow precision to be set? Thanks, Jason