JAVA　保留两位小数的四种方法

     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();          }      }