java保留小数

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);
}//高精度大数

public void m2() {
DecimalFormat df = new DecimalFormat("0.00");
System.out.println(df.format(f));
}//格式定义

public void m3() {
System.out.println(String.format("%.2f", f));
}
<span style="white-space:pre">		</span>
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();
}
}