Question

java 什么是单向链表 和 双向链表 ？

这个代码哪里有体现出链表？

import java.awt.Color;
import java.awt.Graphics;
import java.awt.event.KeyEvent;

public class Snake {
Node head = null;
Node tail = null;
int size = 0;

Node nodes = new Node(25,25, Dir.L);

public Snake() {
head = nodes;
tail = nodes;
size = 1;
}

public void AddToHead() {
Node nodes = null;

switch(head.dir) {
case L :
nodes = new Node(head.row, head.col - 1, head.dir );
break;
case U :
nodes = new Node(head.row - 1, head.col, head.dir );
break;
case R :
nodes = new Node(head.row, head.col + 1, head.dir );
break;
case D :
nodes = new Node(head.row + 1, head.col, head.dir );
}
nodes.next = head;
head.prev = nodes; // ???
head = nodes;
size ++;
}

public void drwa(Graphics g) {
if(size <=0) return;

for(Node n=head; n!=null; n = n.next) {
n.draw(g);
}
move();
}

public void move() {
AddToHead();
DleToTail();
}

public void DleToTail() { //???
if(size ==0) return;
tail = tail.prev;
tail.next = null;
}

public class Node {
int w = Yard.BOX_SIZE;
int h = Yard.BOX_SIZE;
Node next = null;

int row, col;
Dir dir;
Node prev; //???

public Node(int row, int col, Dir dir) {
this.row = row;
this.col = col;
this.dir = dir;
}

public void draw(Graphics g) {
Color c = g.getColor();
g.setColor(Color.RED);
//g.fillRect( row * Yard.BOX_SIZE, col * Yard.BOX_SIZE, w, h);///????
g.fillRect( col * Yard.BOX_SIZE, row * Yard.BOX_SIZE, w, h);
g.setColor(c);
}
}

public void KeyPressed(KeyEvent e) {
int key = e.getKeyCode();
switch(key) {
case KeyEvent.VK_LEFT :
head.dir = Dir.L;
break;
case KeyEvent.VK_UP :
head.dir = Dir.U;
break;
case KeyEvent.VK_RIGHT :
head.dir = Dir.R;
break;
case KeyEvent.VK_DOWN :
head.dir = Dir.D;
break;
}
}

}

Answer 1

链表是类似一种数据结构的东西，就是分别存放有地址以及数据单项链表一般是上一个存放地址的地方存放下一个节点的地址，而双向的就是有两个存放地址的地方，分别存上一个以及下一个的地址。大概是这样子

Answer 2

public Snake() {
head = nodes;
tail = nodes;
size = 1;
}

public void AddToHead() {
Node nodes = null;

switch(head.dir) {
case L :
nodes = new Node(head.row, head.col - 1, head.dir );
break;
case U :
nodes = new Node(head.row - 1, head.col, head.dir );
break;
case R :
nodes = new Node(head.row, head.col + 1, head.dir );
break;
case D :
nodes = new Node(head.row + 1, head.col, head.dir );
}
nodes.next = head;
head.prev = nodes; // ???
head = nodes;
size ++;
}

public void drwa(Graphics g) {
if(size <=0) return;

for(Node n=head; n!=null; n = n.next) {
n.draw(g);
}
move();
}

public void move() {
AddToHead();
DleToTail();
}

public void DleToTail() { //???
if(size ==0) return;
tail = tail.prev;
tail.next = null;
}

public class Node {
int w = Yard.BOX_SIZE;
int h = Yard.BOX_SIZE;
Node next = null;

int row, col;
Dir dir;
Node prev; //???

public Node(int row, int col, Dir dir) {
this.row = row;
this.col = col;
this.dir = dir;
}
你这些的操作中都涉及到了链表。链表的操作是通过指针的移动实现的。

追问

不是很明白，能说的详细些吗？

追答

单向链表：只有个头指针； 双向链表：有个头指针和尾指针。
两个链表在进行添删改查操作时，指针的移动是不相同的，但是原理都一样，看下关于数据结构的书就明白了。我也好久没接触了，有点忘记了。

Answer 3

http://zhidao.baidu.com/question/122288261.html
其实我也不是很懂。。。我帮你找了一下 你看看吧

Answer 4

那种东西在java里体现的并不明显，你只需要知道其原理就可以了。