java保留两位小数4种方法[通俗易懂]

 1     import java.math.BigDecimal;
 2     import java.text.DecimalFormat;
 3     import java.text.NumberFormat;
 4     public class format {
 5         double f = 111231.5585;
 6         public void m1() {
 7             BigDecimal bg = new BigDecimal(f);
 8             double f1 = bg.setScale(2, BigDecimal.ROUND_HALF_UP).doubleValue();
 9             System.out.println(f1);
10         }
11         /**
12          * DecimalFormat转换最简便
13          */
14         public void m2() {
15             DecimalFormat df = new DecimalFormat("#.00");
16             System.out.println(df.format(f));
17         }
18         /**
19          * String.format打印最简便
20          */
21         public void m3() {
22             System.out.println(String.format("%.2f", f));
23         }
24         public void m4() {
25             NumberFormat nf = NumberFormat.getNumberInstance();
26             nf.setMaximumFractionDigits(2);
27             System.out.println(nf.format(f));
28         }
29         public static void main(String[] args) {
30             format f = new format();
31             f.m1();
32             f.m2();
33             f.m3();
34             f.m4();
35         }
36     }