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A:迭代器概述
* 集合是用来存储元素,存储的元素需要查看,那么就需要迭代(遍历)
import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
import com.heima.bean.Student;
@SuppressWarnings({ "rawtypes", "unchecked" })
public class Demo5_Iterator {
public static void main(String[] args) {
// TODO Auto-generated method stub
demo1();
demo2();
}
public static void demo2() {
Collection c=new ArrayList();
c.add(new Student("张三",23));//Object obj=new Student("张三",23);
c.add(new Student("李四",24));
c.add(new Student("王五",25));
c.add(new Student("赵六",26));
Iterator it=c.iterator();//获取迭代器
while(it.hasNext()) {
Student aa=(Student)it.next();//向下转型,使用子类的属性和行为
System.out.println(aa.getName());
}
}
public static void demo1() {
Collection c1=new ArrayList();
c1.add("a");
c1.add("b");
c1.add("c");
c1.add("d");
//对集合中的元素进行迭代(遍历)
Iterator it=c1.iterator();//获取迭代器
// boolean b1=it.hasNext();//判断集合中是否有元素,有就返回true
// Object obj1=it.next();
// System.out.println(b1);
// System.out.println(obj1);
//
//
// boolean b2=it.hasNext();//判断集合中是否有元素,有就返回true
// Object obj2=it.next();
// System.out.println(b2);
// System.out.println(obj2);
while(it.hasNext()) {
System.out.println(it.next());
}
}
}