How to insert an element before the specified element in the linked list, so that the time complexity is n. For example I want to insert 100 before 7

LinkedList<Integer> linkedList = new LinkedList<>(); for(int i=1;i<=10;i++){ linkedList.add(i); } 

I can do it like this

int index = linkedList.indexOf(7); if(-1 != index){ linkedList.add(index,100); } 

But I have traversed the linked list twice by this way. Actually we can do this just by traversing one time. So how can I do that?
PS：just use LinkedList

How to insert an element before the specified element in the linked list, so that the time complexity is n. For example I want to insert 100 before 7

LinkedList<Integer> linkedList = new LinkedList<>(); for (int i = 1; i <= 10; i++) {  linkedList.add(i); } 

I can do it like this

int index = linkedList.indexOf(7); if (-1 != index) {  linkedList.add(index, 100); } 

But I have traversed the linked list twice by this way. Actually we can do this just by traversing one time. So how can I do that?
PS：just use LinkedList

How to insert an element before the specified element in the linked list, so that the time complexity is n. For example I want to insert 100 before 7

LinkedList<Integer> linkedList = new LinkedList<>(); for(int i=1;i<=10;i++){ linkedList.add(i); } 

I can do it like this

int index = linkedList.indexOf(7); if(-1 != index){ linkedList.add(index,100); } 

But I have traversed the linked list twice by this way. Actually we can do this just by traversing one time. So how can I do that?

How to insert an element before the specified element in the linked list, so that the time complexity is n. For example I want to insert 100 before 7

LinkedList<Integer> linkedList = new LinkedList<>(); for(int i=1;i<=10;i++){ linkedList.add(i); } 

I can do it like this

int index = linkedList.indexOf(7); if(-1 != index){ linkedList.add(index,100); } 

But I have traversed the linked list twice by this way. Actually we can do this just by traversing one time. So how can I do that?
PS：just use LinkedList