If one of them is missing, I'll suppress printing its name as well, so I can tell the difference between it being absent and being set to an empty string.
The difference here is that the format string must identify, with each format specification, which dictionary entry will be used to provide the substitution.
这里的差异是，格式字符串必须为每个格式定义指定使用哪个词典条目提供替换。
3
The main difference is that a HashMap is instantiated that associates a String value to a String key.