主要分析內容：
一、Collections工具類別兩種sort()方法
二、範例
一、Collections工具類別兩種sort()方法
格式一：一、Collections工具類別兩種sort() List
都是Comparable介面的子類，即只有是Comparable介面子類別類型的數據，才能進行比較排序。如果其他類型的資料要進行比較排序，必須繼承Comparable介面並
void sort(List
super T> super T>
二、範例範例中取得字串和數字的公用方法：
/**
* 生成随机 不重复的字符串 : number 生成字符串个数
*/
public static List<String> generateString(int number) {
List<String> listString = new ArrayList<>(); // 用于存放返回值
List<Integer> length = null; // 字符串长度
StringBuffer sb = new StringBuffer(); // 中间变量
int control = 0; // 控制个数
String[] chars = 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", "0", "1", "2", "3", "4", "5",
"6", "7", "8", "9", "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" };
while (true) {
// 控制结束
if ( control==number ) {
break;
}
// 生成随机数，生成36位的2aaab761-4341-4968-aceb-3861ee3824b2 UUID类型数据
String uuid = UUID.randomUUID().toString().replace("-", "");
sb.setLength(0);
// 获得随机字符串长度，长度不为0
do {
length = getDiffNo(1, 11);
} while ( length.get(0)==0 );
// 拼凑字符串
for (int i=0; i<length.get(0); i++) {
String str = uuid.substring(i*3, (i*3+3));
//将str字符串转换为16进制，获得其值
int x = Integer.parseInt(str, 16);
//取余：x % 0x3E--0x3E = 3*16 + 14 = 62, 其中chars有62个字符
sb.append(chars[x % 0x3E]);
}
listString.add(sb.toString());
control++;
}
return listString;
}
/**
* 生成随机不重复的数字 :n生成个数 max生成范围
*/
public static List<Integer> getDiffNo(int n, int max) {
// 生成 [0-n] 个不重复的随机数
// list 用来保存这些随机数
List<Integer> list = new ArrayList<>();
Random random = new Random();
Integer k;
for (int i=0; i<n; i++) {
do {
k = random.nextInt(max);
} while (list.contains(k));
list.add(k);
}
return list;
}/**
* 1.通过Collections.sort()方法，对Integer泛型的List进行排序；
* 创建一个Integer泛型的List，插入十个100以内的不重复随机整数， 调用Collections.sort()方法对其进行排序
* 2.排序规则：先数字后字母，数字0-9，字母A-Z a-z的顺序
*/
public void listIntegerSort() {
// 插入十个100以内的不重复随机整数
List<Integer> integerList = getDiffNo(10, 100);
System.out.println("-------------排序前--------------");
for (Integer integer : integerList) {
System.out.println("元素：" + integer);
}
Collections.sort(integerList);
System.out.println("----------------排序后-------------------");
for (Integer integer : integerList) {
System.out.println("元素：" + integer);
}
}/**
* 1.对String泛型的List进行排序； 创建String泛型的List，添加乱序的String元素，
* 调用sort方法，再次输出排序后的顺序
*/
public void listStringSort() {
List<String> stringList = new ArrayList<String>();
stringList.add("eipJlcx");
stringList.add("WvQRufC");
stringList.add("J");
stringList.add("HdaU2G");
stringList.add("M0WswHD3");
System.out.println("------------排序前-------------");
for (String string : stringList) {
System.out.println("元素：" + string);
}
Collections.sort(stringList);
System.out.println("--------------排序后---------------");
for (String string : stringList) {
System.out.println("元素：" + string);
}
}/**
* 对String泛型的List进行排序，要求随机生成10个的不重复字符串，字符串的长度在10以内
*/
public void listStringRandomSort() {
// 生成随机字符串
List<String> listString = generateString(10);
System.out.println("--------------排序前---------------");
for (String integer : listString) {
System.out.println("元素：" + integer);
}
// 排序
Collections.sort(listString);
System.out.println("----------------排序后------------------");
for (String integer : listString) {
System.out.println("元素：" + integer);
}
}/**
* 课程类
* @author Administrator
*
*/
public class Course {
public String id;
public String name;
public Course(String id, String name) {
this.id = id ;
this.name = name;
}
public Course() {
}
@Override
public int hashCode() {
final int prime = 31;
int result = 1;
result = prime * result + ((name == null) ? 0 : name.hashCode());
return result;
}
@Override
public boolean equals(Object obj) {
if (this == obj)
return true;
if (obj == null)
return false;
if (!(obj instanceof Course))
return false;
Course other = (Course) obj;
if (name == null) {
if (other.name != null)
return false;
} else if (!name.equals(other.name))
return false;
return true;
}
}import java.util.HashSet;
import java.util.Set;
/**
* 学生类
* @author Administrator
*
*/
public class Student implements Comparable<Student> {
public String id;
public String name;
public Set<Course> courses;
public Student(String id, String name) {
this.id = id;
this.name = name;
this.courses = new HashSet<Course>();
}
@Override
public int hashCode() {
final int prime = 31;
int result = 1;
result = prime * result + ((name == null) ? 0 : name.hashCode());
return result;
}
@Override
public boolean equals(Object obj) {
if (this == obj)
return true;
if (obj == null)
return false;
if (!(obj instanceof Student))
return false;
Student other = (Student) obj;
if (name == null) {
if (other.name != null)
return false;
} else if (!name.equals(other.name))
return false;
return true;
}
@Override
public int compareTo(Student o) { // 设置ID为比较项
// TODO Auto-generated method stub
return this.id.compareTo(o.id);
}
}import java.util.Comparator;
public class StudentComparator implements Comparator<Student> {
@Override
public int compare(Student o1, Student o2) {
// TODO Auto-generated method stub
return o1.name.compareTo(o2.name);
}
}/**
* 对其他类型泛型的List进行排序，以Student为例。
*/
public void listComparatorSort() {
List<Student> studentList = new ArrayList<Student>();
List<Integer> list = getDiffNo(4, 1000);
studentList.add(new Student(list.get(0) + "", "Mike"));
studentList.add(new Student(list.get(1) + "", "Angela"));
studentList.add(new Student(list.get(2) + "", "Lucy"));
studentList.add(new Student(1000 + "", "Beyonce"));
System.out.println("--------------排序前---------------");
for (Student student : studentList) {
System.out.println("学生：" + student.id + ":" + student.name);
}
// 实现Comparator<T>接口，设置ID比较方式
Collections.sort(studentList);
System.out.println("----------------按照ID排序后------------------");
for (Student student : studentList) {
System.out.println("学生：" + student.id + ":" + student.name);
}
// 实现Comparator<T>接口，设置特定比较方式，以name比较排序
Collections.sort(studentList, new StudentComparator());
System.out.println("----------------按照姓名排序后-----------------");
for (Student student : studentList) {
System.out.println("学生：" + student.id + ":" + student.name);
}
}rrreee
參考學習連接：Comparable介面的實作與使用：http://www.cnblogs.com/gnuhpc/archive/2012/12/17/2822251.htmllect.對List排序的兩種方法：http://blog.csdn.net/wxx614817/article/details/50628197
