What does mean in java

in java means generic, which means any type.

For example: HashMap, you can set K and V to any class when using it.

HashMapK, V is the same as E. HashMap represents a class. This class has two sub-variable types: String and Integer, which can be understood this way.

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The following program:

Map map=new HashMap<String, String();

State that K (key) and V (value) can only be of String type, Only if all Keys and Values ​​in your map are of type String, the program you write will be compiled.

List list=new ArrayList<Object();

Declare that all E (elements) in the list are of type Object.

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