1 import java.util.ArrayList;
 2 
 3 import com.heima.bean.Person;
 4 
 5 public class Demo5_ArrayListArrayList {
 6     /*
 7      * 集合嵌套之ArrayList嵌套ArrayList 案例:一個學校有好多班級,一個班級又有好多人;遍歷輸出這個學校的所有人
 8      */
 9     public static void main(String[] args) {
10         ArrayList<ArrayList<Person>> school = new
 
 ArrayList<>();
11         ArrayList<Person> class1 = new ArrayList<>();
12         class1.add(new Person("張三", 23));
13         class1.add(new Person("李四", 24));
14         class1.add(new Person("王五", 25));
15         ArrayList<Person> class2 = new ArrayList<>();
16         class2.add(new
 
 Person("張三一", 23));
17         class2.add(new Person("李四一", 24));
18         class2.add(new Person("王五一", 25));
19         school.add(class1);
20         school.add(class2);
21         for (ArrayList<Person> outer : school) {
22             for (Person in : outer) {
23                 System.out.println(in);
 
24             }
25         }
26 
27     }
28 
29 }

集合嵌套之ArrayList嵌套ArrayList