java - Why is it not enough to change just nextNode in this data structure? -

java - Why is it not enough to change just nextNode in this data structure? -

in next info structure

public class listnode<t> { t data; listnode<t> nextnode; listnode(t object) { this(object, null); } listnode(t object, listnode<t> node) { info = object; nextnode = node; } public t getdata() { homecoming data; } public listnode<t> getnextnode() { homecoming nextnode; } } public class list<t> { private listnode<t> firstnode; private listnode<t> lastnode; private string name; public list() { this("list"); } public list(string listname) { name = listname; firstnode = lastnode = null; } public void insertatfront(t insertitem) { if(isempty()) firstnode = lastnode = new listnode<t>(insertitem); else firstnode = new listnode<t>(insertitem, firstnode); } public void insertatback(t insertitem) { if(isempty()) firstnode = lastnode = new listnode<t>(insertitem, null); else lastnode = lastnode.nextnode = new listnode<t>(insertitem) } }

why not sufficient just

else lastnode.nextnode = new listnode<t>(insertitem)

in insertatback method? (i not sure a = b = c = something mean in java.)

it's not sufficient this:

else lastnode.nextnode = new listnode<t>(insertitem)

because list needs maintain track of first , lastly nodes. when insert @ back, must update lastnode, otherwise lastnode refer "old" lastly node, second-to-last.

if list empty, neither first nor lastly node set anything; must initialized.

the a = b = c = something syntax assigns lastly value/expression variables not last, associating right-to-left, e.g. something gets assigned c, b, , a.

java data-structures