java对浮点数保留合适的位数

import java.text.DecimalFormat;

public class Main {
    public static void main(String[] args) {
        double number = 3.1415926;
        
        DecimalFormat df = new DecimalFormat("#.0#");
        
        String formatted;
        if (number % 1 == 0) {
            formatted = df.format(number);
        } else {
            df.setMaximumFractionDigits(2);
            formatted = df.format(number);
        }
        
        System.out.println(formatted); // 输出：3.14
    }
}