英文:
Using %n as new line
问题
如推荐的示例中所示：
https://stackoverflow.com/a/38077906/12340711
>最好使用%n作为与操作系统无关的换行符，而不是\n，而且比使用System.lineSeparator()更容易。
然而，该函数对我不起作用：
\n:
System.out.println("foo\nbar");
>>>foo
>>>bar
按预期运行。
%n:
System.out.println("foo%nbar");
>>>foo%nbar
未被解释。
有人能解释一下为什么 %n 对我不起作用吗？它可能不再受支持，还是我漏了什么？
英文:
as recommended as for example in this post:
https://stackoverflow.com/a/38077906/12340711
>It's better to use %n as an OS independent new-line character instead of \n and it's easier than using System.lineSeparator()
However, the function does not work for me:
\n:
System.out.println("foo\nbar");
>>>foo
>>>bar
works as it should.
%n:
System.out.println("foo%nbar");
>>>foo%nbar
is not interpreted.
Can somebody explain me why %n does not work for me? Is it perhaps not longer supported or am I missing something?
答案1
得分: 3
Java为您提供了System.lineSeparator()常量。如果您使用println，它将以与操作系统无关的方式换行。如果您只是在编写代码时尝试，您也可以在字符串中使用\n来换行。这很简单和快速。请注意，println只是将纯文本打印到控制台。
当您使用printf时，实际上将使用java.util.Formatter在控制台输出之前对字符串进行格式化。关于java.util.Formatter的所有细节可以在（Java 8文档链接）找到：https://docs.oracle.com/javase/8/docs/api/java/util/Formatter.html
因此，如果您想要使用println格式化字符串，您需要首先使用java.util.Formatter对其进行格式化，例如：
String formattedStr = String.format("%s = %d %n hello", "joe", 35);
System.out.println(formattedStr);
其中%s表示字符串，%d表示整数，%n表示换行（在上面的文档链接中有描述）。
printf实际上是上述2行代码的快捷方式，其中String.format已经包含在printf的实现中。
System.out.printf("%s = %d %n hello", "joe", 35);
您还可以在printf字符串中使用\n：
System.out.printf("%s = %d \n hello", "joe", 35);
最后，重要的是要理解，在实际项目中，如果您没有使用java.util.Formatter（在Formatter中使用%n），您应该始终使用System.lineSeparator()而不是\n。此外，您不应该在实际项目中使用System.out.*，而应改用日志记录框架。
英文:
Java provides you the System.lineSeparator() constant. That will break the line in a OS independent way if you are using println. You can also just use \n in a string to break the line if you are just playing around with code. It's easy and fast. Note that println just prints a pure text to the console.
When you use printf, you will actually be using a java.util.Formatter to format the string before the console output. All details of the java.util.Formatter can be found at (Java 8 docs link): https://docs.oracle.com/javase/8/docs/api/java/util/Formatter.html
So, if you want to format a string using println, you will need to format it first using java.util.Formatter with something like:
String formattedStr = String.format("%s = %d %n hello", "joe", 35);
System.out.println(formattedStr);
Where %s is a string, %d is a integer number and %n a line break (described in documentation link above).
printf is just a shortcut to the above 2 lines of code where the String.format is already inside printf implementation.
System.out.printf("%s = %d %n hello", "joe", 35);
And you can also use \n in a printf string:
System.out.printf("%s = %d \n hello", "joe", 35);
Finally, it is important for you to understand that in a real world project you should always use System.lineSeparator() instead \n if you are not using a java.util.Formatter (in a Formatter, use %n). Also, you should never use System.out.* for real projects. Use a logging framework instead.
答案2
得分: 2
%n被System.out.println()解释为String。
要使用%n，您必须使用System.out.printf()，就像您所发布的示例中那样。
注意：\n被System.out.printf()解释为换行。
英文:
%n is interpreted as String by System.out.println().
To use %n, you must use System.out.printf(), like in the example you have posted.
Note: \n is interpreted as newline by System.out.printf().
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