java--container (auto-boxing/unboxing)

"Pack/Unpack"

when you need to add a value to a map, it is inconvenient to have the new object come out and the output to be forced type conversion. The use of the map interface in JDK1.5 provides a new mechanism.
Automatic packing/unpack at the right time (only after JDK1.5)<1> automatically converts the underlying type to an object<2> convert objects to the underlying type automatically "Program Analysis" Note: This can be written after JDK1.5:M1.put ("One", 1);//Thrown in is still an object, but internally converted to int type       M2.containvalue (1); int i = (Integer) m1.get ();//coercion type conversion integer here can not be ignored    

java--container (auto-boxing/unboxing)