Several methods of java double type to retain two decimal places

The 4 methods are all rounded, for example:

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 conversion is the easiest
         */
        public void m2() {
            DecimalFormat df = new DecimalFormat("0.00");
            df.setRoundingMode(RoundingMode.HALF_UP);
            System.out.println(df.format(f));
        }
        /**
         * String.format is the easiest to print
         */
        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();
        }
    }

There is also a direct upward integer

<h2 class="title content-title"> //java:Java rounding function</h2> 
<div id="content" class="content mod-cs-content text-content clearfix"> //Math. floor(), Math.ceil(), BigDecimal are all rounding functions in Java, but the return value is different

             Math.floor()
             // The return value calculated by this function is the value after the decimal point is rounded off
             // like:
             Math.floor(3.2) //return 3
             Math.floor(3.9) //return 3
             Math.floor(3.0) //return 3

             Math.ceil()
             //The ceil function will return the integer part +1 as long as the decimal point is not 0
             //like:
             Math.ceil(3.2) //return 4
             Math.ceil(3.9) //return 4
             Math.ceil(3.0) //return 3 </div>