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设计模式简介（一）——Iterator

时间： 2021-07-31 作者：daque

[手段] 供给一种本领程序考察一个会合东西中各个元素, 而又不需表露该东西的里面表白。 [何时运用？] 考察一个会合东西的实质而无需表露它的里面表白。扶助对会合东西的多种遍历。为遍历各别的会合构造供给一个一致的接口(即, 扶助多态迭代)。

[怎样运用？] java作风的示例步调：

//笼统的汇合 public interface aggregate {

public abstract iterator iterator();}

//笼统的iterator public interface iterator {

public abstract boolean hasnext(); public abstract object next();}

//简直的汇合 public class concreteaggregate implements aggregate {

private object[] collection; private int last = 0; public concreteaggregate() {

collection = new object[3];}

public object getitemat(int index) {

return collection[index];}

public void appenditem(object item) {

this.collection[last] = item; last++;}

public int getlength() {

return last;}

public iterator iterator() {

//爆发符合本人的iterator return new concreteiterator(this);}}

//简直的iterator public class concreteiterator implements iterator {

private concreteaggregate namecollection; //由它确定遍历的汇合典型 private int index; public concreteiterator(concreteaggregate collection) {

this.namecollection = collection; this.index = 0; }

public boolean hasnext() {

if (index < namecollection.getlength()) {

return true;} else {

return false;} } public object next() {

//经过一致的getitemat()接话柄现对各别典型汇合的遍历 object item = namecollection.getitemat(index); index++; return item;}}

public class iteratorexample { public static void main(string[] args) { concreteaggregate collection = new concreteaggregate(); collection.appenditem(new person("davis")); collection.appenditem(new person("frank")); collection.appenditem(new person("jeny"));

//it的简直典型依附于collection的典型而运用者并不须要关怀这内里的辨别

iterator it = collection.iterator(); //归来符合collection的iterator while (it.hasnext()) { person person = (person)it.next(); system.out.println("" + person.getname());}}}

如许遍历代码维持了一致的作风，进而使运用者不用关怀遍历的东西究竟是什么典型。

设计模式简介（一）——Iterator

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