Merge Two Sorted Linked Lists

merge.java

Node MergeLists(Node headA, Node headB) {
    Node list1 = headA;
    Node list2 = headB;
    
    Node newList = null;
    Node lastNode = null;
    
    int toPut = 0;
    
    while (list1 != null || list2 != null) {
        
        if (list1 == null && list2 == null)
            break;
        
        if(list2 == null){
            toPut = list1.data;
            list1 = list1.next;
        }
        else if(list1 == null){
            toPut = list2.data;
            list2 = list2.next;
        }
        else if(list1.data < list2.data){
            toPut = list1.data;
            list1 = list1.next;
        }
        else{
            toPut = list2.data;
            list2 = list2.next;
        }
        
        Node newNode = new Node();
        newNode.data = toPut;
        
        if (newList == null)
            lastNode = newList = newNode;
        else
            lastNode = lastNode.next = newNode;
        
    }
    
    return newList;

}