java 保留两位小数点的方法

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();

        }
    }