在java中什么是从另一个数字串减去1的数字字符串的最佳方式

Question

要处理以下问题

String findDifference(String, String) 
{ 
    str1 - str2 
} 

如果其中

str1 = "1002456789100245678910024567891002456789100245678910024567891002456789100245678910024567891002456789100245678910024567891002456789100245678910024567891002456789"; 
    str2 = "0022446611002244661100224466110022446611002244661100224466110022446611002244661100224466110022446611002244661100224466110022446611002244661100224466110022446611"; 
    output = "1000010178100001017810000101781000010178100001017810000101781000010178100001017810000101781000010178100001017810000101781000010178100001017810000101781000010178" 

    str1 = "1002456789100245678910024567891002456789100245678910024567891002456789100245678910024567891002456789100245678910024567891002456789100245678910024567891002456789100245678910024567891002456789100245678910024567891002456789"; 
    str2 = "0022446611000000000000224466110000000000002244661100000000000022446611000000000000224466110000000000002244661100000000000022446611000000000000224466110000000000002244661100000000000022446611000000000000224466110000000000"; 
    output = "1000010178100245678910000101781002456789100001017810024567891000010178100245678910000101781002456789100001017810024567891000010178100245678910000101781002456789100001017810024567891000010178100245678910000101781002456789" 

难道还有比穿越STR1 CTR什么更好的/优化的方法（0，n-1）Integer.parseInt（str1 [ctr]） - Integer.parseInt（str2 [ctr]）并将结果附加到输出[ctr]？

BigInteger会处理这么大的数字吗？

Answer 1

你交出的数字非常大 - 大于int。如果你想处理任意大的数字（内存允许），你需要使用的BigInteger：

public static String findDifference(String str1, String str2) { 
    return new BigInteger(str1).subtract(new BigInteger(str2)).toString(); 
} 

请注意，你的例子是错误的 - 输出不是为str1 - str2正确的结果。

如果我用这个小的驱动程序：

public static void main(String[] args) { 
    System.out.println(findDifference("10024567891002456789", "00224466110000000000")); 
    System.out.println(findDifference("1002456789", "0022446611")); 
    System.out.println(findDifference("1234567", "0111100")); 
} 

我得到这个输出，并用计算器验证表明，这是正确的：

9800101781002456789 
980010178 
1123467