使用 DecimalFormat 显示填充零
我正在使用 DecimalFormat 将双精度数设置为 2 位小数，如下所示:
I'm using DecimalFormat to format doubles to 2 decimal places like this:
DecimalFormat dec = new DecimalFormat("#.##");
double rawPercent = ( (double)(count.getCount().intValue()) /
(double)(total.intValue()) ) * 100.00;
double percentage = Double.valueOf(dec.format(rawPercent));
它有效，但如果我有一个像 20 这样的数字，它会给我这个:
It works, but if i have a number like 20, it gives me this:
20.0
我想要这个:
20.00
有什么建议吗?
推荐答案
DecimalFormat 类用于将十进制数值转换为字符串.在您的示例中，您正在获取来自 format() 方法的字符串并将其放回双变量中.如果您随后输出该双变量，您将看不到格式化的字符串.请参阅下面的代码示例及其输出:
The DecimalFormat class is for transforming a decimal numeric value into a String. In your example, you are taking the String that comes from the format( ) method and putting it back into a double variable. If you are then outputting that double variable you would not see the formatted string. See the code example below and its output:
int count = 10;
int total = 20;
DecimalFormat dec = new DecimalFormat("#.00");
double rawPercent = ( (double)(count) / (double)(total) ) * 100.00;
double percentage = Double.valueOf(dec.format(rawPercent));
System.out.println("DF Version: " + dec.format(rawPercent));
System.out.println("double version: " + percentage);
哪些输出:
"DF Version: 50.00"
"double version: 50.0"
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