Dark Horse programmers learn hashset experience

 

 

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The hashset is an unordered set. an unordered set means that the order in which elements are put is different from the order obtained.

In addition, this set cannot store the same elements.

Now the problem arises. How does hashset determine whether two elements are the same?

Hashset is first judged by the hashcode () method of the element object,

The hashcode () method can be used to calculate a value and compare it with this value. If the value is the same, another method equals () will be called to compare it.

If the hashcode values of the two elements are the same, it determines whether the return value of the equals method is true. If it is true, the hashset considers it to be the same element and will not be saved in the set.

If the hashcode values of the two elements are different, the equals () method is not called. hashset considers that not the same element will be stored in a set.

 

As described above, we can also manually save an element as two elements into the hashset,

Override only requires the hashcode () method and equals () method. For example

Staticn int I = 1;

Public int hashcode ()

{I ++}

You only need to let the hashcode () method return different values or the equals () method return false

 

 

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