泛型限定<? extends Object>

关于泛型限定：

<? extends E >向上限定。意思就是说只能传递E类型以及E类型的子类;

代码：

package itheima;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

/**
 * 泛型限定
 * @author Administrator
 *
 */
public class GenericityLimit {
	public static void main(String[] args) {
		ArrayList<Student> students=new ArrayList<Student>();
		students.add(new Student("student1"));
		students.add(new Student("student2"));
		students.add(new Student("student3"));
		printColl(students);
	}
	//定义一个迭代方法
	public static void printColl(ArrayList<? extends Person> list){
		Iterator<? extends Person> it=list.iterator();
		while(it.hasNext()){
			System.out.println(it.next().getName());
		}
	}
}

class Person{
	private  String name;
	
	protected Person(String name) {
		super();
		this.name = name;
	}

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}
	
}
class Student extends Person{
	public Student(String name){
		super(name);
	}
}

泛型限定<? extends Object>

原文：http://blog.csdn.net/u014010769/article/details/46137375