Java中printf的双%格式问题
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Double % formatting question for printf in Java
提问by D. Spigle
%sis a string in printf, and %d is a decimal I thought...yet when putting in
%s是一个字符串printf，而 %d 是我认为的小数......但在放入时
writer.printf("%d dollars is the balance of %s\r\n", bal, nm);
..an exception is thrown telling me that %d!= lang.double. Ideas?
.. 抛出异常告诉我%d!= lang.double。想法？
采纳答案by codaddict
%dis for integers use %finstead, it works for both floatand doubletypes:
%d用于整数%f，它适用于float和double类型：
double d = 1.2;
float f = 1.2f;
System.out.printf("%f %f",d,f); // prints 1.200000 1.200000
回答by Adeel Ansari
Yes, %dmeans decimal, but it means decimal number system, not decimal point.
是的，%d表示十进制，但表示十进制数制，而不是小数点。
Further, as a complement to the former post, you can also control the number of decimal points to show. Try this,
此外，作为对前一篇文章的补充，您还可以控制显示的小数点数。尝试这个，
System.out.printf("%.2f %.1f",d,f); // prints 1.20 1.2
For more please refer to the API docs.
有关更多信息，请参阅API 文档。
回答by Andy
Yes, %d is for decimal (integer), double expect %f. But simply using %f will default to up to precision 6. To print all of the precision digits for a double, you can pass it via string as:
是的，%d 是十进制（整数），double 期望 %f。但简单地使用 %f 将默认为高达 6 的精度。要打印双精度数的所有精度数字，您可以通过字符串将其传递为：
System.out.printf("%s \r\n",String.valueOf(d));
or
或者
System.out.printf("%s \r\n",Double.toString(d));
This is what println do by default:
这是 println 默认所做的：
System.out.println(d)
(and terminates the line)
（并终止该行）
回答by Salazar
Following is the list of conversion characters that you may use in the printf:
以下是您可以在 printf 中使用的转换字符列表：
%d – for signed decimal integer
%f – for the floating point
%o – octal number
%c – for a character
%s – a string
%i – use for integer base 10
%u – for unsigned decimal number
%x – hexadecimal number
%% – for writing % (percentage)
%n – for new line = \n
