设计模式-行为型-迭代器模式

1、定义

迭代器模式：一种遍历访问容器对象中各个元素的方法，不暴露该对象内部结构

写法

/**
 * 迭代器模式
 */
public interface Iterator<T> {

    /**
     * 是否有下一个元素
     * @return
     */
    boolean hasNext();

    /**
     * 返回当前元素，并将位置移至下一位
     */
    T next();

}

public interface Collection<T> {
    Iterator<T> iterator();
}

/**
 * list列表迭代
 * @param <T>
 */
public class ListIterator<T> implements Iterator<T>{

    private List<T> array;
    private int position;

    public ListIterator(List<T> list){
        this.array = list;
        position = 0;
    }

    @Override
    public boolean hasNext() {
        return !(position > array.size() -1 || array.get( position ) == null);
    }

    @Override
    public T next() {
        T element = array.get( position );
        position ++ ;
        return element;
    }

}

/**
 * 雇员
 */
public class Employee {
    private String name;// 姓名
    private int age;// 年龄
    private String sex;// 性别
    private String position;// 职位

    public Employee(String name, int age, String sex, String position) {
        this.name = name;
        this.age = age;
        this.sex = sex;
        this.position = position;
    }

    @Override
    public String toString() {
        return "Employee{" +
                "name='" + name + '\'' +
                ", age=" + age +
                ", sex='" + sex + '\'' +
                ", position='" + position + '\'' +
                '}';
    }
}

/**
 * 公司
 */
public class CompanyLi implements Collection<Employee>{

    private Iterator<Employee> iterator;

    public CompanyLi(){
        List<Employee> list = new ArrayList<>(  );
        list.add(new Employee("小民", 26, "男", "程序猿"));
        list.add(new Employee("小芸", 22, "女", "测试"));
        list.add(new Employee("小方", 18, "女", "测试"));
        list.add(new Employee("可儿", 21, "女", "设计"));
        iterator = new ListIterator<>( list );
    }

    @Override
    public Iterator<Employee> iterator() {
        return iterator;
    }
}

/**
 *
 * 迭代器模式
 *
 * 遍历又不暴露细节
 *
 * 支持对容器对象的多种遍历。弱化了容器类与遍历算法之间的关系
 *
 */
public class TestMain {

    public static void main(String[] args) {

        CompanyLi companyLi = new CompanyLi();

        //迭代
        Iterator iterator = companyLi.iterator();
        while (iterator.hasNext()){
            System.out.println(iterator.next().toString());
        }

    }

}

代码示例

https://github.com/yinlingchaoliu/23-design-pattern