java开发经验-面向接口编程中迭代器的妙用
使用接口进行编程
定义接口
/**
* 5:36:11 5:37:02 5:37:15 5:37:45 6:19:54 6:21:04 6:22:22 6:23:04
* @author Administrator
* 访问权限 类 包 子类 其他包 描述
public ∨ ∨ ∨ ∨ 其它楼房的人也能用我, 外星人不能用我
protect ∨ ∨ ∨ × 只有我自己和与我住在同一个楼房里的人以及我的子孙能用我
default ∨ ∨ × × 只有我自己和与我住在同一个楼房里的人能用我
private ∨ × × × 只有我自己可以用我
*
*/
public interface Graph {
public int V();
public int E();
public void addEdge(int v,int w);
void show();
public boolean hasEdge(int v,int w);
public Iterable<Integer> adj(int v);
}
通过定义迭代器对邻接矩阵和邻接表图的遍历操作进行了统一
邻接矩阵实现Graph
public class DenseGraph implements Graph{
private int[][] map;
private int N;
private int M;
private boolean isdirected;
public DenseGraph (int n, boolean isdirected) {
super();
map = new int[N][N];
N = n;
M = 0;
this.isdirected = isdirected;
}
@Override
public int V() {
// TODO Auto-generated method stub
return N;
}
@Override
public boolean hasEdge(int v, int w) {
// TODO Auto-generated method stub
if(map[v-1][w-1]!=0) return true;
return false;
}
@Override
public Iterable<Integer> adj(int v) {
// TODO Auto-generated method stub
List<Integer> list = new ArrayList<>();
for(int i=0;i<N;i++) {
if(map[v][i]==1) {
list.add(i);
}
}
return list;
}
@Override
public int E() {
// TODO Auto-generated method stub
return M;
}
@Override
public void show() {
// TODO Auto-generated method stub
for(int i=0;i<N;i++) {
for(int j=0;j<N;j++) {
System.out.print(map[i][j]+"\t");
System.out.println();
}
}
}
@Override
public void addEdge(int v, int w) {
// TODO Auto-generated method stub
if(hasEdge(v,w)) return;
map[v][w] =1;
if(!isdirected)
map[w][v] =1;
M++;
}
}邻接表实现Graph
public class ListSparseGraph implements Graph{
private int N;
private int M;
private List<LinkedList<Integer>> totallist;
private boolean isDirected;
public ListSparseGraph(int n, boolean isDirected) {
super();
N = n;
this.M = 0;
this.isDirected = isDirected;
totallist = new ArrayList<>();
for(int i=0;i<N;i++) {
totallist.add(new LinkedList<Integer>());
}
}
@Override
public int V() {
// TODO Auto-generated method stub
return N;
}
@Override
public int E() {
// TODO Auto-generated method stub
return M;
}
@Override
public void addEdge(int v, int w) {
// TODO Auto-generated method stub
if(hasEdge(v, w)) return;
totallist.get(v).add(w);
if(!isDirected)
totallist.get(w).add(v);
}
@Override
public void show() {
// TODO Auto-generated method stub
for(int i=0;i<N;i++) {
/*for(int j =0;j<totallist.get(i).size();j++) {
System.out.println(totallist.get(i));
}*/
System.out.print("vertex"+ i+":\t");
for(Integer item:totallist.get(i)) {
System.out.print(item+"\t");
}
System.out.println();
}
}
@Override
public boolean hasEdge(int v, int w) {
// TODO Auto-generated method stub
for(Integer m:totallist.get(v)) {
if(m==w) return true;
}
return false;
}
@Override
public Iterable<Integer> adj(int v) {
// TODO Auto-generated method stub
return totallist.get(v);
}
}面向接口编程，传入不同实现的引用
public class Main {
public static void main(String[] args) {
// TestG1.txt
String filename1 = "testG1.txt";
ListSparseGraph g1 = new ListSparseGraph(13, false);
ReadGraph readGraph1 = new ReadGraph(g1, filename1);
Compents component1 = new Compents(g1);
System.out.println("TestG1.txt, Component Count: " + component1.count());
System.out.println();
// TestG2.txt
String filename2 = "testG2.txt";
DenseGraph g2 = new DenseGraph(6, false);
ReadGraph readGraph2 = new ReadGraph(g2, filename2);
Compents component2 = new Compents(g2);
System.out.println("TestG2.txt, Component Count: " + component2.count());
}
}接受一个图的引用，因为迭代器可以使得对不同图的遍历操作达到了统一
public class Compents {
Graph graph;
private boolean[] visited;
private int count;
private int[] ids;
public Compents(Graph graph) {
this.graph = graph;
int V = graph.V();
visited = new boolean[V];
ids = new int[V];
count = 0;
for(int i=0;i<V;i++) {
ids[i] = -1;
}
//connect numbers
for(int i=0;i<V;i++) {
if(!visited[i]) {
DFS(i);
count++;
}
}
}
private void DFS(int i) {
// TODO Auto-generated method stub
visited[i] = true;
ids[i] = count;
for(int item :graph.adj(i)) { //迭代器遍历图
if(!visited[item])
DFS(item);
}
}
}
