java保留2位小数的4中步骤

java保留2位小数的4中方法

package com.china.test.format;

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();
??? }
}