为什么Java中的这三个值发生了变化？

Question

为什么值sH，eH和bH改变了？

因为这三个值只使用一次。我真的不明白这个问题。

public class Problem_08_SmallerEqualBigger {

    public static class Node {
        public int value;
        public Node next;

        public Node(int data) {
            this.value = data;
        }
    }

    public static Node listPartition2(Node head, int pivot) {
        Node sH = null; // Small head
        Node sT = null; // Small tail
        Node eH = null; // Equal head
        Node eT = null; // Equal tail
        Node bH = null; // Big head
        Node bT = null; // Big tail
        Node next = null; // Save next node

        // Every node distributed to three lists
        while (head != null) {
            next = head.next;
            head.next = null;
            if (head.value < pivot) {
                if (sH == null) {
                    sH = head;
                    sT = head;
                } else {
                    sT.next = head;
                    sT = head;
                }
                // 1 2 3 4 5 6
            } else if (head.value == pivot) {
                if (eH == null) {
                    eH = head;  //1
                    eT = head;  //1
                } else {
                    eT.next = head;  // 1 ->2   2->3
                    eT = head;
                }
            } else {
                if (bH == null) {
                    bH = head;
                    bT = head;
                } else {
                    bT.next = head;
                    bT = head;
                }
            }
            head = next;
        }
        // Small and equal reconnect
        if (sT != null) {
            sT.next = eH;
            eT = eT == null ? sT : eT;
        }

        // All reconnect
        if (eT != null) {
            eT.next = bH;
        }
        return sH != null ? sH : eH != null ? eH : bH;
    }
}