java.util.Formatter : UnknownFormatConversionException: Conversion = 'F'

Question

怎么了

public String toString() {
    return super.toString()
            + String.format(" %1$F-%2$F", startDate, endDate);
}

我明白了

Caused by: java.util.UnknownFormatConversionException: Conversion = 'F' at java.util.Formatter$FormatSpecifier.conversion(Formatter.java:2606) at java.util.Formatter$FormatSpecifier.(Formatter.java:2634) at java.util.Formatter.parse(Formatter.java:2480) at java.util.Formatter.format(Formatter.java:2414) at java.util.Formatter.format(Formatter.java:2367) at java.lang.String.format(String.java:2769)

我想打印 java.util.Formatter 中定义的 ISO 8601 日期

Answer 1

我认为日期格式化模式需要一个前缀:

't', 'T'    date/time   Prefix for date and time conversion characters. See Date/Time Conversions. 

F 修饰符的示例也显示了这种语法:

'F'     ISO 8601 complete date formatted as "%tY-%tm-%td". 

所以下面的模式应该有效:

String.format(" %1$tF-%2$tF", startDate, endDate);