A quote from the book I’m reading Head First Java: The point is that hashcodes can be the same without necessarily guaranteeing that the objects are equal, because the “hashing algorithm” used in the hashCode() method might happen to return the same value for multiple objects. Why might the hashCode() method return the same value for different objects? Does that
Tag: hash
How can I generate an MD5 hash in Java?
Is there any method to generate MD5 hash of a string in Java? Answer You need java.security.MessageDigest. Call MessageDigest.getInstance(“MD5”) to get a MD5 instance of MessageDigest you can use. The compute the hash by doing one of: Feed the entire input as a byte[] and calculate the hash in one operation with md.digest(bytes). Feed the MessageDigest one byte[] chunk at
Why does Java’s hashCode() in String use 31 as a multiplier?
Per the Java documentation, the hash code for a String object is computed as: using int arithmetic, where s[i] is the ith character of the string, n is the length of the string, and ^ indicates exponentiation. Why is 31 used as a multiplier? I understand that the multiplier should be a relatively large prime number. So why not 29,