In Java, what is the API used by auto-boxing/unboxing?

Question

I recently went to a Java interview, and the interviewer asked me this question. I know about boxing and unboxing, but the concept of API is very vague, and I don’t even know what the API used by boxing and unboxing is. I hope someone can help me answer it

Answer 1

This blog is written more clearly: Java automatic boxing and unboxing and their pitfalls

Answer 2

Look at this piece of code first

        Integer a = 1;
        int b = 2;
        int c = a + b;
        Integer d = a + b;

This is the debugging result

In Java, only the same type can be directly calculated, but no transformation is performed here. When Integer and int are calculated in the third line, they will be automatically unboxed and converted to int type for calculation, and the fourth line will be converted to int calculation first. After the result is obtained, it is automatically packaged into Integer

Answer 3

Take integer as an example, Integer.intValue() and Integer.valueOf(int x)