[英]Compare two hex strings in Java?
I am implementing a simple DHT using the Chord protocol in Java. 我正在使用Java中的Chord协议实现一个简单的DHT。 The details are not important but the thing I'm stuck on is I need to hash strings and then see if one hashed string is "less than" another. 细节并不重要,但我坚持的是我需要哈希字符串,然后查看一个哈希字符串是否“小于”另一个。
I have some code to compute hashes using SHA1 which returns a 40 digit long hex string (of type String in Java) such as: 我有一些使用SHA1计算哈希值的代码,它返回一个40位长的十六进制字符串(Java中的String类型),例如:
69342c5c39e5ae5f0077aecc32c0f81811fb8193
However I need to be able to compare two of these so to tell, for example that: 但是,我需要能够比较其中两个,以便告诉我,例如:
0000000000000000000000000000000000000000
is less than: 小于:
FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF
This is the complete range of values as the 40 digit string is actually representing 40 hex numbers in the range 0123456789ABCDEF 这是完整的值范围,因为40位数字符串实际上代表0123456789ABCDEF范围内的40个十六进制数字
Does anyone know how to do this? 有谁知道如何做到这一点?
Thanks in advance. 提前致谢。
The values 0..9
and A..F
are in hex-digit order in the ASCII character set, so 值0..9
和A..F
在ASCII字符集中以十六进制顺序排列,因此
string1.compareTo(string2)
should do the trick. 应该做的伎俩。 Unless I'm missing something. 除非我错过了什么。
BigInteger one = new BigInteger("FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF",16);
BigInteger two = new BigInteger("0000000000000000000000000000000000000000",16);
System.out.println(one.compareTo(two));
System.out.println(two.compareTo(one));
Output: 输出:
1 1
-1 -1
1 indicates greater than -1 indicates less than 0 would indicate equal values 1表示大于-1表示小于0表示相等的值
Since hex characters are in ascending ascii order (as @Tenner indicated), you can directly compare the strings: 由于十六进制字符按升序ascii顺序(如@Tenner所示),您可以直接比较字符串:
String hash1 = ...;
String hash2 = ...;
int comparisonResult = hash1.compareTo(hash2);
if (comparisonResult < 0) {
// hash1 is less
}
else if (comparisonResult > 0) {
// hash1 is greater
}
else {
// comparisonResult == 0: hash1 compares equal to hash2
}
Since the strings are fixed length and '0' < '1' < ... < 'A' < ... < 'Z' you can use compareTo
. 由于字符串是固定长度和'0'<'1'<... <'A'<... <'Z',您可以使用compareTo
。 If you use mixed case hex digits use compareToIgnoreCase
. 如果使用混合大小写十六进制数字,请使用compareToIgnoreCase
。
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