List集合的排序实现

java中关于list的集合的排序实现方式：
实现方法一：实体类实现comparable接口
   public class User implements Comparable<User>{
private String name;
private Integer age;
        此处省略get、set方法
        @Override
public int compareTo(User o) {
    return this.getAge().compareTo(o.getAge());
}
     }
   测试方法：
     public class ComparatorUser {
       public static void main(String[] args0) {
List<User> list = new ArrayList<User>();
for (int i = 0; i < 10; i++) {
int age = new Random().nextInt(100);
System.out.println("age:" + age);
String[] str = new String[] { "a", "b", "c", "d", "e",      "f", "g", "h", "i", "j", "k", "l", "m", "n", "o", "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z", "A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M","N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z" };
String name = "";
for (int k = 0; k < 6; k++) {
name += str[new Random().nextInt(47)];
}
System.out.println("name:" + name);
User u = new User();
u.setAge(age);
u.setName(name);
list.add(u);
}
Collections.sort(list);
for (User user : list) {
System.out.println(user.getName() + ":" + user.getAge());
}
}
}
实现方法二：继承comparator接口
  此处省略Student对象的创建代码。
  public class ComparatorStudent implements Comparator<Student> {
public static void main(String[] args) {
List<Student> list = new ArrayList<Student>();
for (int i = 0; i < 10; i++) {
int age = new Random().nextInt(100);
System.out.println("age:" + age);
String[] str = new String[] { "a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m", "n", "o", "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z", "A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M","N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z" };
String name = "";
for (int k = 0; k < 6; k++) {
name += str[new Random().nextInt(47)];
}
System.out.println("name:" + name);
Student u = new Student();
u.setAge(age);
u.setStuId(name);
list.add(u);
}
Comparator<Student> comparator = new ComparatorStudent();
Collections.sort(list, comparator);
for(Student stu : list){
System.out.println("stuID:"+stu.getStuId()+"age:"+stu.getAge())
}
}

/**
* @see java.util.Comparator#compare(java.lang.Object, java.lang.Object)
*/
@Override
public int compare(Student o1, Student o2) {
/**
* equals 0 : o1 = o2
* greater 0 : 01 > 02
* less 0 : o1 < o2
*/
int flag = o1.getAge().compareTo(o2.getAge());
return flag;
}
}

在以上实现方法中，数值类的比较，只能是Integer类型，在Comparator接口中，指定的数值比较类型为Integer类型,flag = Integer.comparaTo(Integer anothersValue),其返回值flag有三种值：=0，<0，>0


以上两种实现方法的结果是一样的 ，均可实现list集合的排序