Iterator Study 【002】

尚学堂_马士兵_第七章_Iterator学习

package com.iterator;
import java.util.Iterator ; 
import java.util.Collection ;
import java.util.HashSet ;
public class TestIterator {
	public static void main(String ages[]) {
		Collection c = new HashSet() ;
		c.add(new Name("f1","11")) ;
		c.add(new Name("f2","22")) ;
		c.add(new Name("f3","33")) ;
		Iterator i = c.iterator() ;
		while(i.hasNext()) {
			//next 返回值是object 类型，需要转换成相应类型，此处也用到多态
			Name name = (Name)i.next() ; //将游标移到下一个位置
			System.out.println(name.getFirstName()) ;
		}
		
		//   remove
		c.add(new Name("f4","4444")) ;
		c.add(new Name("f5","55")) ;
		c.add(new Name("f6","666")) ;
		for(Iterator j =c.iterator(); j.hasNext();  ) {
			Name name = (Name)j.next() ;
			if(name.getSecondName().length() < 3 ) 
				j.remove();
			  //c.remove(name) ;  //不能调用容器本身的remove方法，iterator 内部执行了锁定，就其内部可看
		}
		System.out.println(c) ;
	}

}
class Name {
	private String firstName ;
	private String secondName ;
	public Name(String firstName, String secondName) {
		this.firstName = firstName ;
		this.secondName = secondName ;
	}
	public String getFirstName() {
		return firstName ;
	}
	public String getSecondName() {
		return secondName ;
	}
	public String toString() {
		return firstName + " " + secondName ;
	}
}

结果：
f2
f1
f3
[f6 666, f4 4444]

HashSet无序，所以遍历出来的结果会不一样