Node: An individual part of a larger data structure
Nodes are a basic data structure which contain data and one or more links to other nodes. Nodes can be used to represent a tree structure or a linked list. In such structures where nodes are used, it is possible to traverse from one node to another node.
Orphaned nodes
Nodes that have no links pointing to them except for the head node, are considered “orphaned.” In the illustration, if the nodes a2 and a5 are removed, they will be orphaned.
Null node link
Data structures containing nodes have typically two bits of information stored in a node: data and link to next node.
The first part is a value and the second part is an address of sorts pointing to the next node. In this way, a system of nodes is created. A NULL value in the link part of a node’s info denotes that the path or data structure contains no further nodes.
Node Class Overview
A Node class in Java has the following attributes:
publicStringdataandprivateNodenextinstance variables- a constructor that takes
Stringdataas an argument and sets thedatainstance variable to it as well as setsnexttonull .setNextNode()to set thenextproperty.getNextNode()to access thenextproperty
public class Node {
public String data;
private Node next;
public Node(String data) {
this.data = data;
this.next = null;
}
public void setNextNode(Node node) {
this.next = node;
}
public Node getNextNode() {
return this.next;
}
}Node Constructor
A Node constructor should take in data as a variable. Our implementation had data as a String, but it could also be an int or float, etc. The constructor should then:
- set the
datainstance variable to the passed indatavariable - set the
nextinstance variable tonull
public Node(String data) {
this.data = data;
this.next = null;
}Set Next Node
A Java Node class has a .setNextNode() method that takes in a Node and updates the next instance variable appropriately.
public void setNextNode(Node node) {
this.next = node;
}
Get Next Node
A Java Node class has a .getNextNode() method with no parameters that returns the next class property.
public Node getNextNode() {
return this.next;
}