java保留2位小数的4种方式

import java.math.BigDecimal;
import java.text.DecimalFormat;
import java.text.NumberFormat;

public class format {
   double f = 111231.5585;
   public void m1() {
       BigDecimal bg = new BigDecimal(f);
       double f1 = bg.setScale(2, BigDecimal.ROUND_HALF_UP).doubleValue();
       System.out.println(f1);
   }
   /**
    * DecimalFormat转换最简便
    */
   public void m2() {
       DecimalFormat df = new DecimalFormat("#.00");
       System.out.println(df.format(f));
   }
   /**
    * String.format打印最简便
    */
   public void m3() {
       System.out.println(String.format("%.2f", f));
   }
   public void m4() {
       NumberFormat nf = NumberFormat.getNumberInstance();
       nf.setMaximumFractionDigits(2);
       System.out.println(nf.format(f));
   }
   public static void main(String[] args) {
       format f = new format();
       f.m1();
       f.m2();
       f.m3();
       f.m4();
   }
}