Java Review the list interface of the collection class

List as ordered and repeatable lists

The class that implements the list interface is primarily ArrayList

The following is the test code for ArrayList

Importjava.util.ArrayList; Public classDemo4 { Public Static voidmain (String [] args) {ArrayList A1=NewArrayList (); A1.add (NewInteger (11)); A1.add (NewInteger (23)); A1.add (NewInteger (65)); A1.add (NewInteger (28)); A1.add (NewInteger (72)); A1.add (NewInteger (98));                SYSTEM.OUT.PRINTLN (A1); //Conversion GroupObject a[] =A1.toarray (); intsum = 0;  for(inti=0; i<a.length; i++) Sum+=((Integer) a[i]). Intvalue (); System.out.println ("Sum:" +sum); }}

Code Analysis:

Instantiate an ArrayList object first A1

Adding elements to the Add () method

Output the entire list

Then convert the collection A1 to the array, using the method of ToArray ()

The Intvalue () method is used in the calculation of the sum of the arrays: you can convert the wrapper type to the underlying type value

Finish

Java Review the list interface of the collection class