Visitor

最後編輯：2017-07-03 建立：2017-07-01 歷史紀錄

ERIC Yimport java.util.*;
public interface Checker {
//訪問者check不同的對象會做不同的事情
public void check(State s);
//
public void check(Transition t);
//
public void check(StateDiagram sd);
//
}
public interface DiagramElement {
//接受訪客訪問的介面
public void accept(Checker c);
}
public class SyntaxCheck implements Checker{
//SyntaxCheck實做checker
public void check(State s) {
//印出SytaxCheck State的結果
System.out.println("SyntaxCheck");
}
public void check(Transition t) {
System.out.println("SyntaxCheck");
}
public void check(StateDiagram sd) {
System.out.println("SyntaxCheck");
}
}
public class RelationCheck implements Checker{
public void check(State s) {
System.out.println("RelationCheck");
}
public void check(Transition t) {
System.out.println("RelationCheck");
}
public void check(StateDiagram sd) {
System.out.println("RelationCheck");
}
}
public class State implements DiagramElement {
@Override
public void accept(Checker c) {
//訪問這透過accept介面去check此物件
c.check(this);
}
}
public interface DiagramElement {
//接受訪客訪問的介面
public void accept(Checker c);
}
public class StateDiagram implements DiagramElement{
private ArrayList<DiagramElement> element = new ArrayList<DiagramElement>();
public void add(DiagramElement e){
element.add(e);
}
@Override
public void accept(Checker c) {
//訪問這透過accept介面去check此物件
c.check(this);
Iterator itr = element.iterator();
while(itr.hasNext()){
//訪問者check StateDiagram底下的element
((DiagramElement)itr.next()).accept(c);
}
}
}