Java基礎集錦——利用Collections.sort方法對list排序

標籤：

　　要想對List進行排序，可以讓實體物件實現Comparable介面，重寫compareTo方法即可實現按某一屬性排序，但是這種寫法很單一，只能按照固定的一個屬性排序，沒變法變化。通過下面這種方法，可以動態指定List按照某一個屬性進行排序，例子很簡單，看代碼就明白了。

　　

import java.util.ArrayList;import java.util.Collections;import java.util.Comparator;import java.util.List;public class testCollection {    /**     * @param args     */    public static void main(String[] args) {        User u1=new User();        u1.setName("Jessica");        u1.setAge(20);        User u2=new User();        u2.setName("Abobo");        u2.setAge(30);        List<User> userList=new ArrayList<User>();        userList.add(u1);        userList.add(u2);        MyComparator sort=new MyComparator();        MyComparator2 sort2=new MyComparator2();        MyComparator3 sort3=new MyComparator3();        MyComparator4 sort4=new MyComparator4();        Collections.sort(userList,sort);        for (User u:userList) {            System.out.println(u.toString()+";I am "+(userList.indexOf(u)+1)+" and I‘m ordered by Name desc");        }        Collections.sort(userList,sort2);        for (User u:userList) {            System.out.println(u.toString()+";I am "+(userList.indexOf(u)+1)+" and I‘m ordered by Name asc");        }        Collections.sort(userList,sort3);        for (User u:userList) {            System.out.println(u.toString()+";I am "+(userList.indexOf(u)+1)+" and I‘m ordered by Age desc");        }        Collections.sort(userList,sort4);        for (User u:userList) {            System.out.println(u.toString()+";I am "+(userList.indexOf(u)+1)+" and I‘m ordered by Age asc");        }    }    public static class MyComparator implements Comparator<User>{        @Override        public int compare(User o1, User o2) {            return -o1.getName().compareTo(o2.getName());        }            }    public static class MyComparator2 implements Comparator<User>{        @Override        public int compare(User o1, User o2) {            return o1.getName().compareTo(o2.getName());        }            }    public static class MyComparator3 implements Comparator<User>{        @Override        public int compare(User o1, User o2) {            return -o1.getAge().compareTo(o2.getAge());        }            }    public static class MyComparator4 implements Comparator<User>{        @Override        public int compare(User o1, User o2) {            return o1.getAge().compareTo(o2.getAge());        }            }}

 結果：

Hello!My Name is Jessica and I‘m 20;I am 1 and I‘m ordered by Name descHello!My Name is Abobo and I‘m 30;I am 2 and I‘m ordered by Name descHello!My Name is Abobo and I‘m 30;I am 1 and I‘m ordered by Name ascHello!My Name is Jessica and I‘m 20;I am 2 and I‘m ordered by Name ascHello!My Name is Abobo and I‘m 30;I am 1 and I‘m ordered by Age descHello!My Name is Jessica and I‘m 20;I am 2 and I‘m ordered by Age descHello!My Name is Jessica and I‘m 20;I am 1 and I‘m ordered by Age ascHello!My Name is Abobo and I‘m 30;I am 2 and I‘m ordered by Age asc

 　　通過這種方法，可以選擇為List排序的方式了，打好地基，才能逐漸穩固的長城。

Java基礎集錦——利用Collections.sort方法對list排序