單鏈表的添加和刪除元素
public class LinkedList<E> {
private Node head;
private int size;
public LinkedList() {
this.head = null;
this.size = 0;
}
public void add(int index, E e) {
if (index < 0 || index > size) {
throw new IllegalArgumentException("index 錯(cuò)誤");
}
if (index == 0) {
addFirst(e);
} else {
Node prev = head;
for (int i = 0; i < index - 1; i++) {
prev = prev.next;
}
Node node = new Node(e);
node.next = prev.next;
prev.next = node;
size++;
}
}
public void addFirst(E e) {
Node node = new Node(e);
node.next = head;
head = node;
size++;
}
public int getSize() {
return size;
}
public boolean isEmpty() {
return size == 0;
}
public E remove(int index) {
if (index < 0 || index > size) {
throw new IllegalArgumentException("索引錯(cuò)誤");
}
if (index == 0) {
return removeFirst();
} else {
Node prev = head;
for (int i = 0; i < index - 1; i++) {
prev = prev.next;
}
Node removeNode = prev.next;
prev.next = removeNode.next;
removeNode.next = null;
size--;
return removeNode.e;
}
}
public E removeFirst() {
Node node = head;
head = head.next;
size--;
return node.e;
}
@Override
public String toString() {
StringBuilder str = new StringBuilder();
Node node = this.head;
while (node != null) {
str.append(node.e);
str.append("->");
node = node.next;
}
str.append("NULL");
return str.toString();
}
private class Node {
public Node next;
public E e;
public Node(Node next, E e) {
this.next = next;
this.e = e;
}
public Node() {
this(null, null);
}
public Node(E e) {
this(null, e);
}
}
}
