Java output retains two decimal digits __java

Today in doing pat007-six-degree space, the output needs to retain two decimal places, so the relevant information on the Internet.

There are a total of four methods , the code is as follows:

Import Java.math.BigDecimal;
Import Java.text.DecimalFormat;
Import Java.text.NumberFormat;

public class decimals{
    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 simplest/public
    void m2 () {
        DecimalFormat df = new DecimalFormat ("#.00");
        System.out.println (Df.format (f));
    }
    /**
     * String.Format printing is easiest/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) {
    	decimals F = new decimals ();
        F.M1 ();
        F.M2 ();
        F.M3 ();
        F.M4 ();
    }