[java]_[Collections.sort()实现List排序]

List<String> list = new ArrayList();list.add("刘媛媛");

list.add("王硕");
list.add("李明");
list.add("刘迪");
list.add("刘布");

//升序
Collections.sort(list,Collator.getInstance(java.util.Locale.CHINA));//注意：是根据的汉字的拼音的字母排序的，而不是根据汉字一般的排序方法
for(int i=0;i<list.size();i++)
{
    System.out.print(list.get(i));
}
System.out.println("");

//降序
Collections.reverse(list);//不指定排序规则时，也是按照字母的来排序的
for(int i=0;i<list.size();i++)
{
     System.out.print(list.get(i));
}

结果：

李明刘布刘迪刘媛媛王硕
王硕刘媛媛刘迪刘布李明

自定义排序：

1.第一种是model类实现Comparable接口，重写重写int compareTo(Object o)方法

public class StudentDTO implements Comparable
{
 private String name;
 private int age;

public String getName()
{
    return name;
}

public void setName(String name)
{
     this.name = name;
}

public ObjType getType()
{
    return type;
}

public void setAge(int age)
{
     this.age= age;
}

@Override
public int compareTo(Object o)
{

       StudentDTO sdto = (StudentDTO)o;

       int otherAge = sdto.getAge();
      // note: enum-type's comparation depend on types' list order of enum method
      // so, if compared property is enum-type ,then its comparationfollow ObjEnum.objType order


      return this.age.compareTo(otherAge);
}
}

调用：

public static void main(String[] args)
{
      List<StudentDTO> studentList = new ArrayList();

      StudentDTO s1 = new StudentDTO ();

      s.setName("yuanyuan");

      s.setAge(22);

      studentList.add(s1);

                  StudentDTO s1 = new StudentDTO ();

                  s.setName("lily");

                  s.setAge(23);

                  studentList.add(s2);

                  Collections.sort(studentList);  //按照age升序 22，23，

                 Collections.reverse(studentList);  //按照age降序 23,22   

}

2. 比较器类实现Comparator接口，重写int compare(Object o1, Object o2)方法

model类：

public class StudentDTO implements Comparable
{
     private String name;
     private int age;

     public String getName()
     {
         return name;
     }

     public void setName(String name)
    {
         this.name = name;
     }

     public ObjType getType()
     {
         return type;
     }

     public void setAge(int age)
     {
         this.age= age;
     }

} 

比较器类：

class MyCompartor implements Comparator
{
     @Override
     public int compare(Object o1, Object o2)
    {

           StudentDTO sdto1= (StudentDTO )o1;

           StudentDTO sdto2= (StudentDTO )o2;

           return sdto1.getAge.compareTo(stdo2.getAge())

    }
}

调用：

public static void main(String[] args)
{
      List<StudentDTO> studentList = new ArrayList();

      StudentDTO s1 = new StudentDTO ();

      s.setName("yuanyuan");

      s.setAge(22);

      studentList.add(s1);

      StudentDTO s1 = new StudentDTO ();

      s.setName("lily");

      s.setAge(23);

      studentList.add(s2);

      MyComparetor mc = new MyComparetor();

      Collections.sort(studentList,mc);     //按照age升序 22，23，

      Collections.reverse(studentList,mc);    //按照age降序 23,22   

}