public class SortTest { public static void main(String[] args) { int arr[]={12,4,45,23,5,7,9,33}; System.out.println("数组冒泡排序-------------------------------------------------------------"); for (int i = 0; i < arr.length; i++) { for (int j = 0; j < arr.length-i-1; j++) { if(arr[j]<arr[j+1]){//从大到小 大数放在最前位 int temp = arr[j]; arr[j] = arr[j+1]; arr[j+1]=temp; } } } for (int i = 0; i < arr.length; i++) { System.out.print(arr[i] + " "); } System.out.println(); System.out.println(); System.out.println("数组sort排序-------------------------------------------------------------"); Arrays.sort(arr);//默认排序是从小到大 for(int i = 0;i < arr.length;i++) { System.out.print(arr[i] + " "); } System.out.println(); System.out.println(); System.out.println("list sort排序-------------------------------------------------------------"); SortTest s = new SortTest(); List<User> list=new ArrayList<User>(); list.add(s.new User(12, "aa")); list.add(s.new User(35, "cc")); list.add(s.new User(14, "bb")); list.add(s.new User(58, "ee")); list.add(s.new User(38, "dd")); //方法一:根据Collections.sort重载方法 Collections.sort(list, new Comparator<User>() { public int compare(User arg0, User arg1) { return arg0.getAge().compareTo(arg1.getAge()); //当前为升序,调换两个位置就是降序 } }); //方法二:User对象实现Comparable接口 //Collections.sort(list); for (int i = 0; i<list.size(); i++) { User user=list.get(i); System.out.println(user.getAge()+" "+user.getName()); } } public class User implements Comparable<User>{ private Integer age;//比较字段类型必须是Integer private String name; public User(){} public User(Integer age,String name){ this.age=age; this.name=name; } public Integer getAge() { return age; } public void setAge(Integer age) { this.age = age; } public String getName() { return name; } public void setName(String name) { this.name = name; } public int compareTo(User arg0) { return this.getAge().compareTo(arg0.getAge()); } } }