How to create a method with an empty parameter list in java

I'm having a brain fart and for some reason I can't figure out how to write a method where the parameters are empty.

I have a method here (empty)

public void removeRepeat() {
}

This is for a linked list and I want to remove repeats. I have other methods below that I'm thinking of using to go about it:

public boolean remove(Object element) {
        Node<T> current = head;
        if(isEmpty()) {
            return false;
        }
        if(current.getValue() == element){
            head = head.getNext();
            size--;
            return true;
        }
        while(current.getNext().getValue() != element) {
            current = current.getNext();
            if(current == null) {
                return false;
            }
        }
        if(current.getNext().getNext() == null) {
            tail = current;
        }
        current.setNext(current.getNext().getNext());
        size--;
        return true;
    }

I also have a set method and whatnot, but my question is generally how to write the method if there are no parameters. Do I just create a new variable? How do I access the list it wants me to reverse? I'm thinking to have a for loop to check for repeats and then remove the repeating element, but I'm not sure how to construct the for loop.
for (int i=0; i< ???; i++)

Broadly speaking there four major ways you can access a variable inside a method in Java:

• Provide the variable as parameter:

public void removeRepeat(SomeObject obj)
{
    // do something with obj
}

• Have the variable be a member (seems like this is true for head in your second code snippet):

SomeObject obj = new SomeObject();
public void removeRepeat()
{
    // do something with obj
}

• Declare the variable locally, i.e. inside the method:

public void removeRepeat()
{
    SomeObject obj = new SomeObject();
    // do something with obj
}

• Have it be available statically somewhere:

// some other class
public class SomeClass
{
    public static final Object obj = new SomeObject();
}
...
// then in your class:
public void removeRepeat()
{
    SomeObject obj = SomeClass.obj;
    // do something with obj
}

I recommend getting over some Java basics, it should clear up some misconceptions you might have about this.

Judging by your remove(Object element) method, you have a class that contains a head and a tail field, as well as a size field.

If you are adding a new method removeRepeat() to the same class, then you can go ahead and access these fields just like in the remove(Object) method.
For example,

public void removeRepeat() {
    // Make a method-local copy of the class's "head" field.
    Node<T> current = head;
    // Iterate through the list here:
    while (current != null) {
        // do something
        current = current.getNext();
    }
    etc...
 }