How to Implement the Remove Method in arraylist

Source code of the arraylistremove method:

 
Public Boolean remove (Object O) {If (O = NULL) {for (INT Index = 0; index <size; index ++) if (elementdata [Index] = NULL) {fastremove (INDEX); return true ;}} else {for (INT Index = 0; index <size; index ++) if (O. equals (elementdata [Index]) {fastremove (INDEX); return true ;}} return false ;}
 

First of all, find the subscript of the object to be deleted. After all, in Java, the List Implementation is implemented using arrays. What does it mean to delete an element, this means that all elements after the element subscript to be deleted are moved to the previous position:

Private void fastremove (INT index) {modcount ++; int nummoved = size-index-1; if (nummoved> 0) system. arraycopy (elementdata, index + 1, elementdata, index, nummoved); elementdata [-- size] = NULL; // Let GC do its work}
 

Elementdata [-- size] = NULL; after all the elements to be deleted are moved one by one, the last element is set to null. The following is testsystemcopy. Java:

 
Package testsystem; public class testsystemcopy {public static void main (string [] ARGs) {string [] strarr = new string [] {"1", "2", "3 ", "4", "5", "6", "7", "8", "9"}; // move the element with the subscript 4 to a system. arraycopy (strarr, 3, strarr, 2, strarr. length-3); strarr [strarr. length-1] = NULL; For (INT I = 0; I <strarr. length; I ++) {system. out. println (strarr [I]) ;}}
 

Array is used in arraylist.