Java的大数操作分为BigInteger和BigDecimal,但这两给类是分开使用的，有时候在编程的时候显得略微繁琐，现在编写了一个将二者合二为一的大数操作类。
大数操作类代码如下:
1 package blog;
2
3 import java.math.BigDecimal;
4 import java.math.BigInteger;
5 import java.math.RoundingMode;
6
7 /**
8 *
9 * @author 瓦尔登湖畔的小木屋
10 * BigNumberOperation封装了对十进制大数整数和大数浮点数的四则运算的操作
11 */
12 public class BigNumberOperation {
13 /**
14 * 对加法的封装操作
15 */
16 public static BigInteger add(BigInteger number1, BigInteger number2) {
17 return number1.add(number2);
18 }
19
20 public static BigDecimal add(BigDecimal number1, BigDecimal number2) {
21 return number1.add(number2);
22 }
23
24 public static BigDecimal add(BigDecimal number1, BigInteger number2) {
25 return number1.add(new BigDecimal(number2));
26 }
27
28 public static BigDecimal add(BigInteger number1, BigDecimal number2) {
29 return new BigDecimal(number1).add(number2);
30 }
31
32 /**
33 * 对减法的封装操作
34 */
35 public static BigInteger subtract(BigInteger number1, BigInteger number2) {
36 return number1.subtract(number2);
37 }
38
39 public static BigDecimal subtract(BigDecimal number1, BigDecimal number2) {
40 return number1.subtract(number2);
41 }
42
43 public static BigDecimal subtract(BigDecimal number1, BigInteger number2) {
44 return number1.subtract(new BigDecimal(number2));
45 }
46
47 public static BigDecimal subtract(BigInteger number1, BigDecimal number2) {
48 return new BigDecimal(number1).subtract(number2);
49 }
50
51 /**
52 * 对乘法的封装操作
53 */
54 public static BigInteger multiply(BigInteger number1, BigInteger number2) {
55 return number1.multiply(number2);
56 }
57
58 public static BigDecimal multiply(BigDecimal number1, BigDecimal number2) {
59 return number1.multiply(number2);
60 }
61
62 public static BigDecimal multiply(BigDecimal number1, BigInteger number2) {
63 return number1.multiply(new BigDecimal(number2));
64 }
65
66 public static BigDecimal multiply(BigInteger number1, BigDecimal number2) {
67 return new BigDecimal(number1).multiply(number2);
68 }
69
70 /**
71 * 对除法的封装
72 * 大数浮点数时，结果默认保留10位小数，也可以通过count指定保留小数的位数
73 * 对于最末一位的取舍采取RoundingMode.HALF_EVEN模式
74 */
75 public static BigInteger divide(BigInteger number1, BigInteger number2) {
76 return number1.divide(number2);
77 }
78
79 public static BigDecimal divide(BigDecimal number1, BigDecimal number2) {
80 return number1.divide(number2, 10, RoundingMode.HALF_EVEN);
81 }
82
83 public static BigDecimal divide(BigDecimal number1, BigDecimal number2, int count) {
84 return number1.divide(number2, count, RoundingMode.HALF_EVEN);
85 }
86
87 public static BigDecimal divide(BigDecimal number1, BigInteger number2) {
88 return number1.divide(new BigDecimal(number2), 10, RoundingMode.HALF_EVEN);
89 }
90
91 public static BigDecimal divide(BigDecimal number1, BigInteger number2, int count) {
92 return number1.divide(new BigDecimal(number2), count, RoundingMode.HALF_EVEN);
93 }
94
95 public static BigDecimal divide(BigInteger number1, BigDecimal number2) {
96 return new BigDecimal(number1).divide(number2, 10, RoundingMode.HALF_EVEN);
97 }
98
99 public static BigDecimal divide(BigInteger number1, BigDecimal number2, int count) {
100 return new BigDecimal(number1).divide(number2, count, RoundingMode.HALF_EVEN);
101 }
102 /*
103 * 由于当两个大数都是字符串时，无法通过重载实现，所以才返回Number,以同时适应BigInteger和BigDecimal
104 */
105 public static Number add(String number1, String number2) {
106 if (number1.matches("[0-9]+") && number2.matches("[0-9]+")) {
107 return new BigInteger(number1).add(new BigInteger(number2));
108 } else {
109 return new BigDecimal(number1).add(new BigDecimal(number2));
110 }
111 }
112
113 public static Number subtract(String number1, String number2) {
114 if (number1.matches("[0-9]+") && number2.matches("[0-9]+")) {
115 return new BigInteger(number1).subtract(new BigInteger(number2));
116 } else {
117 return new BigDecimal(number1).subtract(new BigDecimal(number2));
118 }
119 }
120
121 public static Number multiply(String number1, String number2) {
122 if (number1.matches("[0-9]+") && number2.matches("[0-9]+")) {
123 return new BigInteger(number1).multiply(new BigInteger(number2));
124 } else {
125 return new BigDecimal(number1).multiply(new BigDecimal(number2));
126 }
127 }
128
129 public static Number divide(String number1, String number2) {
130 if (number1.matches("[0-9]+") && number2.matches("[0-9]+")) {
131 return new BigInteger(number1).divide(new BigInteger(number2));
132 } else {
133 return new BigDecimal(number1).divide(new BigDecimal(number2), 10, RoundingMode.HALF_EVEN);
134 }
135 }
136
137 public static BigDecimal divide(String number1, String number2, int count) {
138 return new BigDecimal(number1).divide(new BigDecimal(number2), count, RoundingMode.HALF_EVEN);
139 }
140 }
测试代码如下:
1 package blog;
2
3 import java.math.BigDecimal;
4 import java.math.BigInteger;
5
6 public class Main {
7 public static void main(String[] args) {
8 String str1 = "46556545";
9 String str2 = "45454545.45454544";
10
11 BigInteger num1 = new BigInteger(str1);
12 BigDecimal num2 = new BigDecimal(str2);
13 System.out.println("当两个参数是大数时的测试:");
14 System.out.println("大数加法的测试:");
15 System.out.println(num1 + " + " + num1 + " = " + BigNumberOperation.add(num1, num1));
16 System.out.println(num1 + " + " + num2 + " = " + BigNumberOperation.add(num1, num2));
17 System.out.println(num2 + " + " + num1 + " = " + BigNumberOperation.add(num2, num1));
18 System.out.println(num2 + " + " + num2 + " = " + BigNumberOperation.add(num2, num2));
19 System.out.println();
20
21 System.out.println("大数减法的测试:");
22 System.out.println(num1 + " - " + num1 + " = " + BigNumberOperation.subtract(num1, num1));
23 System.out.println(num1 + " - " + num2 + " = " + BigNumberOperation.subtract(num1, num2));
24 System.out.println(num2 + " - " + num1 + " = " + BigNumberOperation.subtract(num2, num1));
25 System.out.println(num2 + " - " + num2 + " = " + BigNumberOperation.subtract(num2, num2));
26 System.out.println();
27
28 System.out.println("大数乘法的测试:");
29 System.out.println(num1 + " * " + num1 + " = " + BigNumberOperation.multiply(num1, num1));
30 System.out.println(num1 + " * " + num2 + " = " + BigNumberOperation.multiply(num1, num2));
31 System.out.println(num2 + " * " + num1 + " = " + BigNumberOperation.multiply(num2, num1));
32 System.out.println(num2 + " * " + num2 + " = " + BigNumberOperation.multiply(num2, num2));
33 System.out.println();
34
35 System.out.println("大数除法的测试:");
36 System.out.println(num1 + " / " + num1 + " = " + BigNumberOperation.divide(num1, num1));
37 System.out.println(num1 + " / " + num2 + " = " + BigNumberOperation.divide(num1, num2));
38 System.out.println(num2 + " / " + num1 + " = " + BigNumberOperation.divide(num2, num1));
39 System.out.println(num2 + " / " + num2 + " = " + BigNumberOperation.divide(num2, num2));
40 System.out.println("大数除法保留五位小数:");
41 System.out.println(num1 + " / " + num2 + " = " + BigNumberOperation.divide(num1, num2, 5));
42 System.out.println(num2 + " / " + num1 + " = " + BigNumberOperation.divide(num2, num1, 5));
43 System.out.println(num2 + " / " + num2 + " = " + BigNumberOperation.divide(num2, num2, 5));
44 System.out.println("");
45
46 System.out.println("###############################################");
47 System.out.println("当两个参数为字符串是的测试:");
48 System.out.println("加法测试:");
49 System.out.println(str1 + " + " + str1 + " = " + BigNumberOperation.add(str1, str1));
50 System.out.println(str1 + " + " + str2 + " = " + BigNumberOperation.add(str1, str2));
51 System.out.println(str2 + " + " + str1 + " = " + BigNumberOperation.add(str2, str1));
52 System.out.println(str2 + " + " + str2 + " = " + BigNumberOperation.add(str2, str2));
53 System.out.println();
54 System.out.println("减法测试:");
55 System.out.println(str1 + " - " + str1 + " = " + BigNumberOperation.subtract(str1, str1));
56 System.out.println(str1 + " - " + str2 + " = " + BigNumberOperation.subtract(str1, str2));
57 System.out.println(str2 + " - " + str1 + " = " + BigNumberOperation.subtract(str2, str1));
58 System.out.println(str2 + " - " + str2 + " = " + BigNumberOperation.subtract(str2, str2));
59 System.out.println();
60 System.out.println("乘法测试:");
61 System.out.println(str1 + " * " + str1 + " = " + BigNumberOperation.multiply(str1, str1));
62 System.out.println(str1 + " * " + str2 + " = " + BigNumberOperation.multiply(str1, str2));
63 System.out.println(str2 + " * " + str1 + " = " + BigNumberOperation.multiply(str2, str1));
64 System.out.println(str2 + " * " + str2 + " = " + BigNumberOperation.multiply(str2, str2));
65 System.out.println();
66 System.out.println("除法测试:");
67 System.out.println(str1 + " / " + str1 + " = " + BigNumberOperation.divide(str1, str1));
68 System.out.println(str1 + " / " + str2 + " = " + BigNumberOperation.divide(str1, str2));
69 System.out.println(str2 + " / " + str1 + " = " + BigNumberOperation.divide(str2, str1));
70 System.out.println(str2 + " / " + str2 + " = " + BigNumberOperation.divide(str2, str2));
71 System.out.println();
72 System.out.println("除法测试:");
73 System.out.println(str1 + " / " + str1 + " = " + BigNumberOperation.divide(str1, str1, 5));
74 System.out.println(str1 + " / " + str2 + " = " + BigNumberOperation.divide(str1, str2, 5));
75 System.out.println(str2 + " / " + str1 + " = " + BigNumberOperation.divide(str2, str1, 5));
76 System.out.println(str2 + " / " + str2 + " = " + BigNumberOperation.divide(str2, str2, 5));
77 }
78 }
测试结果如下:
当两个参数是大数时的测试:
大数加法的测试:
46556545 + 46556545 = 93113090
46556545 + 45454545.45454544 = 92011090.45454544
45454545.45454544 + 46556545 = 92011090.45454544
45454545.45454544 + 45454545.45454544 = 90909090.90909088
大数减法的测试:
46556545 - 46556545 = 0
46556545 - 45454545.45454544 = 1101999.54545456
45454545.45454544 - 46556545 = -1101999.54545456
45454545.45454544 - 45454545.45454544 = 0E-8
大数乘法的测试:
46556545 * 46556545 = 2167511882337025
46556545 * 45454545.45454544 = 2116206590909090.23190480
45454545.45454544 * 46556545 = 2116206590909090.23190480
45454545.45454544 * 45454545.45454544 = 2066115702479337.5206611570247936
大数除法的测试:
46556545 / 46556545 = 1
46556545 / 45454545.45454544 = 1.0242439900
45454545.45454544 / 46556545 = 0.9763298684
45454545.45454544 / 45454545.45454544 = 1.0000000000
大数除法保留五位小数:
46556545 / 45454545.45454544 = 1.02424
45454545.45454544 / 46556545 = 0.97633
45454545.45454544 / 45454545.45454544 = 1.00000
###############################################
当两个参数为字符串是的测试:
加法测试:
46556545 + 46556545 = 93113090
46556545 + 45454545.45454544 = 92011090.45454544
45454545.45454544 + 46556545 = 92011090.45454544
45454545.45454544 + 45454545.45454544 = 90909090.90909088
减法测试:
46556545 - 46556545 = 0
46556545 - 45454545.45454544 = 1101999.54545456
45454545.45454544 - 46556545 = -1101999.54545456
45454545.45454544 - 45454545.45454544 = 0E-8
乘法测试:
46556545 * 46556545 = 2167511882337025
46556545 * 45454545.45454544 = 2116206590909090.23190480
45454545.45454544 * 46556545 = 2116206590909090.23190480
45454545.45454544 * 45454545.45454544 = 2066115702479337.5206611570247936
除法测试:
46556545 / 46556545 = 1
46556545 / 45454545.45454544 = 1.0242439900
45454545.45454544 / 46556545 = 0.9763298684
45454545.45454544 / 45454545.45454544 = 1.0000000000
除法测试:
46556545 / 46556545 = 1.00000
46556545 / 45454545.45454544 = 1.02424
45454545.45454544 / 46556545 = 0.97633
45454545.45454544 / 45454545.45454544 = 1.00000