Differences and relationships between the hashcode () and Equals () methods

1. What is a hashing algorithm.

First look at a few concepts, the following excerpt from Wikipedia

hash function:

/*
 hash function (or hash algorithm, also known as hash function, English: hash functions) is a way to create a small number "fingerprint" from any kind of data. The
hash function compresses the message or data into a digest, which makes the data quantity smaller and the data format fixed. The function disrupts the data and recreate a
fingerprint called the hash value (hash Values,hash Codes,hash sums, or hashes). A hash value is usually used to represent a short random letter and a string of numbers. A
good hash function rarely has a hash conflict in an input field. In hashing and data processing, not suppressing conflicts to differentiate data makes database records more difficult to find.
 */

The nature of the hash function:

/*
 All hash functions have the following basic characteristics: If the two hash values are different (according to the same function), then the original input of the two hash values is also different.
This property is a deterministic result of the hash function, and a hash function with this property is called a one-way hash function. On the other hand, the input and output of the hash function are not
the only corresponding relationships, if two hash values are the same, two input values are likely to be the same, but may also be different, which is called a "hash collision," which is usually two different lengths
of input values, calculated to calculate the same output value. Enter some data to calculate the hash value, and then partially change the input value, and a hash function with a strong obfuscation attribute produces
a completely different hash value.
 */

Based on the above concept, you can summarize:

As input, do hashing algorithm, the result must be the same;

On the contrary, not tenable.

2. Not finished.