List和Set中 我們要熟記：
List:有序，重復
有序：指按照一定的順序輸出。|| 重復：指可以向list中添加相同的值
Set:無序，唯一
無序：指輸出是沒有順序。 || 唯一：指不添加可以向set中添加相同的元素，如果你添加相同的元素，最后輸出的結果也是唯一的。
如下例子：
public class Demo{
@SuppressWarnings("unchecked")
public static void main(String[] args) {
People p1=new People("AA",144,12.6);
People p2=new People("BB",1,16.6);
People p3=new People("CC",13,11.6);
People p4=new People("DD",2,10.3);
HashSet<People> set=new HashSet<People>();
set.add(p4);
set.add(p4);
set.add(p1);
set.add(p3);
for (People people : set) {
System.out.println(people);
}
}
}
控制台結果：體現出無序和唯一的特性
[name:CC,age:13,height:11.6]
[name:DD,age:2,height:10.3]
[name:AA,age:144,height:12.6]
public class Demo{
@SuppressWarnings("unchecked")
public static void main(String[] args) {
People p1=new People("AA",144,12.6);
People p2=new People("BB",1,16.6);
People p3=new People("CC",13,11.6);
People p4=new People("DD",2,10.3);
ArrayList<People> list=new ArrayList<People>();
list.add(p1);
list.add(p2);
list.add(p3);
list.add(p4);
list.add(p4);
list.add(p4);
list.add(p4);
for (People people : list) {
System.out.println(people);
}
}
}
控制台結果：體現有序，重復的特性
[name:AA,age:144,height:12.6]
[name:BB,age:1,height:16.6]
[name:CC,age:13,height:11.6]
[name:DD,age:2,height:10.3]
[name:DD,age:2,height:10.3]
[name:DD,age:2,height:10.3]
[name:DD,age:2,height:10.3]