java保留兩位小數—四種方法

import java.math.BigDecimal;import java.text.DecimalFormat;import java.text.NumberFormat;public class 保留兩位小數 {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轉換最簡便 */public void m2() {DecimalFormat df = new DecimalFormat("#.00");System.out.println(df.format(f));}/** * String.format列印最簡便 */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) {保留兩位小數 f = new 保留兩位小數();f.m1();f.m2();f.m3();f.m4();}}