在LinkedList Java中打印第一个元素

Question

Everything is working fine int he given code, except that the display does not print the first most inserted element

 public void display()
    {
    Link pcurrent = pfirst;
    while(pcurrent.next!= null)
    {
      System.out.println(pcurrent);
      pcurrent = pcurrent.next;

    }
    }

with elements inserted in order : 100, 200, 300, 400 -> It outputs them as:

//nothing in first turn 
200 
300, 200 (in second iteration)
400, 300, 200 in last iteration

How do I change this?

What I want is this:

 100
  200, 100
  300, 200, 100
  400, 300, 200, 100

Answer 1

From your code, it seems that you intentionally want to skip printing pfirst . If so, try this:

public void display()
{
    Link pcurrent = pfirst.next;
    while(pcurrent!= null)
    {
        System.out.println(pcurrent);
        pcurrent = pcurrent.next;
    }
}

Here, I've changed how pcurrent is initialized before the loop, changed the loop condition, and changed the order of events inside the loop body.

This should perhaps be better done as a for loop:

for (Link pcurrent = pfirst.next; pcurrent != null; pcurrent = pcurrent.next) {
    System.out.println(pcurrent);
}

If you also want to print pfirst (which sounds like what you actually want to do), then just keep the initialization of pcurrent as you currently have it and still make the other changes.

Answer 2

I assume you are inserting the element in the front of the list. Swap your statement in the while loop.

void print(list *head)
{
    list *pcurrent = head;
    while(head != NULL)
    {
      System.out.println(pcurrent);
      pcurrent = pcurrent.next;
    }
}

Answer 3

With your code, you first advancing the pointer then trying to print the value. Just swap the statements in while loop. If you want to print whole list, you should also change the condition of while loop.

  public void display() {
        Link pcurrent = pfirst;
        while(pcurrent!= null) {
                System.out.println(pcurrent);
                pcurrent = pcurrent.next;
         }
   }