如何在Java中打印2位小数的浮点数？
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How to print a float with 2 decimal places in Java?
提问by via_point
Can I do it with System.out.print?
我可以用System.out.print吗？
采纳答案by Anthony Forloney
You can use the printfmethod, like so:
您可以使用该printf方法，如下所示：
System.out.printf("%.2f", val);
In short, the %.2fsyntax tells Java to return your variable (val) with 2 decimal places (.2) in decimal representation of a floating-point number (f) from the start of the format specifier (%).
简而言之，%.2f语法告诉 Java从格式说明符 ( )的开头以浮点数val( .2) 的十进制表示形式返回带有 2 个小数位 ( ) 的变量f( %)。
There are other conversion characters you can use besides f:
除了 ，您还可以使用其他转换字符f：
d: decimal integero: octal integere: floating-point in scientific notation
d: 十进制整数o: 八进制整数e: 科学记数法中的浮点数
回答by Bozho
You can use DecimalFormat. One way to use it:
您可以使用DecimalFormat. 一种使用方法：
DecimalFormat df = new DecimalFormat();
df.setMaximumFractionDigits(2);
System.out.println(df.format(decimalNumber));
Another one is to construct it using the #.##format.
另一种是使用#.##格式构造它。
I find all formatting options less readable than calling the formatting methods, but that's a matter of preference.
我发现所有格式化选项都比调用格式化方法可读性差，但这是一个偏好问题。
回答by Kevin Sylvestre
double d = 1.234567;
DecimalFormat df = new DecimalFormat("#.##");
System.out.print(df.format(d));
回答by Uri
Look at DecimalFormat
Here is an example from the tutorial:
这是教程中的一个示例：
DecimalFormat myFormatter = new DecimalFormat(pattern);
String output = myFormatter.format(value);
System.out.println(value + " " + pattern + " " + output);
If you choose a pattern like "###.##", you will get two decimal places, and I think that the values are rounded up. You will want to look at the link to get the exact format you want (e.g., whether you want trailing zeros)
如果你选择像“###.##”这样的模式，你会得到两个小数位，我认为这些值是四舍五入的。您将需要查看链接以获得所需的确切格式（例如，是否需要尾随零）
回答by u7867
Many people have mentioned DecimalFormat. But you can also use printfif you have a recent version of Java:
很多人都提到过DecimalFormat。但是，printf如果您有最新版本的 Java，也可以使用：
System.out.printf("%1.2f", 3.14159D);
See the docs on the Formatter for more information about the printf format string.
回答by John P.
I would suggest using String.format()if you need the value as a Stringin your code.
如果您需要在代码中将该值作为 a ，我建议使用String.format()String。
For example, you can use String.format()in the following way:
例如，您可以通过String.format()以下方式使用：
float myFloat = 2.001f;
String formattedString = String.format("%.02f", myFloat);
回答by John P.
OK - str to float.
OK - str 浮动。
package test;
import java.text.DecimalFormat;
public class TestPtz {
public static void main(String[] args) {
String preset0 = "0.09,0.20,0.09,0.07";
String[] thisto = preset0.split(",");
float a = (Float.valueOf(thisto[0])).floatValue();
System.out.println("[Original]: " + a);
a = (float) (a + 0.01);
// Part 1 - for display / debug
System.out.printf("[Local]: %.2f \n", a);
// Part 2 - when value requires to be send as it is
DecimalFormat df = new DecimalFormat();
df.setMinimumFractionDigits(2);
df.setMaximumFractionDigits(2);
System.out.println("[Remote]: " + df.format(a));
}
}
Output:
输出：
run:
[Original]: 0.09
[Local]: 0.10
[Remote]: 0.10
BUILD SUCCESSFUL (total time: 0 seconds)
回答by Birk
A simple trick is to generate a shorter version of your variable by multiplying it with e.g. 100, rounding it and dividing it by 100.0again. This way you generate a variable, with 2 decimal places:
一个简单的技巧是通过将它与 eg 相乘100、四舍五入并100.0再次除以生成变量的较短版本。这样您就可以生成一个变量，带有2 个小数位：
double new_variable = Math.round(old_variable*100) / 100.0;
This "cheap trick" was always good enough for me, and works in any language (I am not a Java person, just learning it).
这个“便宜的技巧”对我来说总是足够好，并且适用于任何语言（我不是 Java 人，只是在学习它）。
回答by Aldin Philo
float floatValue=22.34555f;
System.out.print(String.format("%.2f", floatValue));
Output is 22.35. If you need 3 decimal points change it to "%.3f".
输出为 22.35。如果您需要 3 个小数点，请将其更改为“%.3f”。
回答by Pavan vadrevu
small simple program for demonstration:
用于演示的小简单程序：
import java.io.*;
import java.util.Scanner;
public class twovalues {
public static void main(String args[]) {
float a,b;
Scanner sc=new Scanner(System.in);
System.out.println("Enter Values For Calculation");
a=sc.nextFloat();
b=sc.nextFloat();
float c=a/b;
System.out.printf("%.2f",c);
}
}
