动态数组排序：

List
     
       ls=new ArrayList
      
       ();                ls.add(-1);        ls.add(11);        ls.add(100);        ls.add(8);        ls.add(2);        ls.add(10);                Collections.sort(ls);// 升序排列                System.out.print("排序后结果是：");        for(int i:ls){            System.out.print(i+",");        }        System.out.println();                Collections.reverse(ls);// 颠倒        System.out.print("颠倒后结果是：");        for(int i:ls){            System.out.print(i+",");        }
      
     

 

自定义排序规则的例子：

public class Emp  implements Comparable{    private int age;    private int salary;    private String name;        public Emp(String name,int age,int salary){        this.name=name;        this.age=age;        this.salary=salary;    }        public String toString(){        StringBuilder sb=new StringBuilder();                sb.append("姓名:"+name);        sb.append(" 年龄:"+age);        sb.append(" 薪水:"+salary);                return sb.toString();    }        @Override    public int compareTo(Object o) {        Emp another = (Emp) o;                return this.name.compareTo(another.name);                /*if(this.salary!=another.salary){            return this.salary-another.salary;        }else{            return this.age-another.age;        }*/    }            public static void main(String[] args){        List
     
       ls=new ArrayList
      
       ();                ls.add(new Emp("Andy",20,4500));        ls.add(new Emp("Cdins",30,10000));        ls.add(new Emp("Douasa",40,30000));        ls.add(new Emp("cahsa",20,5000));        ls.add(new Emp("Hewqw",30,15000));        ls.add(new Emp("Xawew",60,30000));        ls.add(new Emp("Baod",30,30000));                Collections.sort(ls);// 按compareTo中规则排列                System.out.println("排序后结果是：");        for(Emp i:ls){            System.out.println(i.toString());        }            }}
      
     

将员工信息写入文件的类

public class WriteSample{    public static void main(String[] args){        try {            BufferedWriter out = new BufferedWriter(new FileWriter("c://write.txt"));                        out.write("张三 23 男 3500\r\n");            out.write("李四 24 女 13500\r\n");            out.write("王五 25 男 1500\r\n");            out.write("赵六 93 女 1300");                        out.close();        } catch (IOException e) {            e.printStackTrace();        }    }}

将员工信息读出文件并进行排序的类

import java.io.BufferedReader;import java.io.FileReader;import java.io.IOException;import java.util.ArrayList;import java.util.Collections;import java.util.List;class Emp  implements Comparable{    String name;    int age;    String sex;    int salary;        public Emp(String line){        String[] arr=line.split(" ");        name=arr[0];        age=Integer.parseInt(arr[1]);        sex=arr[2];        salary=Integer.parseInt(arr[3]);    }        public String toString(){        StringBuilder sb=new StringBuilder();                sb.append("姓名:"+name);        sb.append(" 年龄:"+age);        sb.append(" 性别:"+sex);        sb.append(" 薪水:"+salary);                return sb.toString();    }        @Override    public int compareTo(Object o) {        Emp another = (Emp) o;                return this.salary-another.salary;//this.name.compareTo(another.name);                /*if(this.salary!=another.salary){            return this.salary-another.salary;        }else{            return this.age-another.age;        }*/    }}public class ReadSample{    public static void main(String[] args){        try {            List
     
       ls=new ArrayList
      
       ();            BufferedReader in = new BufferedReader(new FileReader("c://write.txt"));            String str;            while ((str = in.readLine()) != null) {                ls.add(new Emp(str));            }            in.close();                                    Collections.sort(ls);                        for(Emp e:ls){                System.out.println(e);            }        } catch (IOException e) {        }    }}