What are packaging classes? What does the packaging class do?

What is a wrapper class?

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A core principle in Java design is that everything is an object, that is to say, everything must be described in the form of an object. But primitive data types are not objects. So how to solve this problem? You can wrap basic data types into an object and use these types with an object-oriented approach.

What does the packaging class do?

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Use basic data type packaging to describe the function to make the function more robust, for example: Integer is not int by default 0 but null, then compared to the basic data type, the wrapper class object has one more state.

Another more intuitive thing is that the packaging class provides us with many methods to use, for example: data can be converted to binary, view the maximum and minimum values, etc.

In addition to the above, there is another important point: basic data types cannot be stored in collections, only objects, so when using collections, we need to use wrapper class objects.

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