What does mean in java

1a4db2c2c2313771e5742b6debf617a1 in java means generic, which means any type.

For example: HashMapb77a8d9c3c319e50d4b02a976b347910, you can set K and V to any class when using it.

HashMap601754196720ae8e56f6948b6d2ab654K, V is the same as E. HashMap601754196720ae8e56f6948b6d2ab654 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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