例子：假設有一個年級，一個年級中存在多個班級，而班級中的每一個學生都是一個物件

ArrayList<Student>表示一個班級，而年級大的集合則可用：ArrayList<ArrayList<Student>>來表示

圖解：

/*
 * 集合的遍歷巢狀
 * 大集合：ArrayList<ArrayList<Football>>
 * */

import java.util.ArrayList;

public class FootballTest {
	public static void main(String[] args){
		//建立ArrayList大集合物件
		ArrayList<ArrayList<Football>> Team = new ArrayList<>();
		
		//建立第一個子集合物件ArrayList<Football>
		ArrayList<Football> team1 = new ArrayList<>();
		Football f1 = new Football("伊卡爾迪",24);
		Football f2 = new Football("坎德雷瓦",27);
		Football f3 = new Football("佩裡西奇",26);
		//給第一個子集合中新增元素
		team1.add(f1);
		team1.add(f2);
		team1.add(f3);
		//將第一個子集合新增至大集合中
		Team.add(team1);
		
		////建立第二個子集合物件ArrayList<Football>
		ArrayList<Football> team2 = new ArrayList<>();
		Football f4 = new Football("塞薩爾",24);
		Football f5 = new Football("托爾多",27);
		Football f6 = new Football("漢達諾維奇",26);
		//給第二個子集合物件中新增元素
		team2.add(f4);
		team2.add(f5);
		team2.add(f6);
		//將第二個子集合新增至大集合中
		Team.add(team2);
		
		//建立第三個子集合物件ArrayList<Football>
		ArrayList<Football> team3 = new ArrayList<>();
		Football f7 = new Football("穆里尼奧",24);
		Football f8 = new Football("斯帕萊蒂",27);
		Football f9 = new Football("弗朗西斯科利",26);
		//新增元素
		team3.add(f7);
		team3.add(f8);
		team3.add(f9);
		//將第三個子集合新增至大集合中
		Team.add(team3);
		
		//遍歷大集合，增強for迴圈：ArrrayList<ArrayList<Football>>
		for(ArrayList<Football> arrayTeam:Team){
			//子集合:ArrayList<Football>
			for(Football arrayFootball:arrayTeam){
				System.out.println(arrayFootball);
			}
		}
		
	}
	
}


class Football{
	String name;
	int age;
	
	public Football(){
		
	}
	
	public Football(String name, int age) {
		super();
		this.name = name;
		this.age = age;
	}

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

	public int getAge() {
		return age;
	}

	public void setAge(int age) {
		this.age = age;
	}
	
	//重寫toString()方法
	public String toString(){
		return name+","+age;
	}

	@Override
	//重寫equals()方法
	public boolean equals(Object obj) {
		Football f = (Football)obj;
		if(f.name==this.name && f.age==this.age){
			return true;
		}
		else{
			return false;
		}
	}
	
}