回合数只有第一位小数 [英] Round number to only first decimal place

问题描述

我想知道可用的手机内存，所以我写了这篇code。

I would like to know the available phone memory, so I wrote this code.

File path2 = Environment.getDataDirectory();
StatFs stat2 = new StatFs(path.getPath());
long blockSize2 = stat.getBlockSize();
long availableBlocks = stat.getAvailableBlocks();
double result = availableBlocks * blockSize;

free = (Preference)this.findPreference("free_mem");
free.setSummary(Double.toString(result)+" GB");

现在的问题是，我得到一个outpout为5.654707363。我试图把只用小数点后第一位。

The problem is that I get a outpout as 5.654707363. I tried to take only the first decimal place using

free = Math.round(size * 10) / 10d;

但不起作用。任何想法？

But doesn't work. Any ideas?

推荐答案

如果我理解你的问题的权利，你需要的NumberFormat 这里：

If I understood your question right you need NumberFormat here:

NumberFormat nf = NumberFormat.getInstance();
nf.setMaximumFractionDigits(1);
nf.format(5.654707363);

生成的 5,7

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