使用比較器實現list排序
主要程式碼:
List<String> list = new ArrayList();list.add("劉媛媛");
list.add("王碩");
list.add("李明");
list.add("劉迪");
list.add("劉布");
Collections.sort(list,Collator.getInstance(java.util.Locale.CHINA));//注意:是根據的漢字的拼音的字母排序的,而不是根據漢字一般的排序方法
for(int i=0;i<list.size();i++)
{
System.out.print(list.get(i));
}
輸出結果:
李明劉布劉迪劉媛媛王碩
2自定義排序規則
(1)model類實現Comparable介面,重寫int compareTo(Object o)方法
model類:
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);
}
}
主方法:
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,
//降序的再呼叫一次反轉(Reverse)
Collections.reverse(studentList);//23,22
}
降序的另一種實現是直接修改compareTo實現比如升序的時候
return
this.age.compareTo(otherAge);
降序則反過來即可
retrun otherAge.compareTo(this.age);
3,新建立一個比較器類實現Comparator介面,重寫int compare(Object o1, Object o2)方法;
model類:
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;
}
}
比較器類:
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())
}
}
主方法:
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
}
升序降序實現方法可參照第二種方式。同樣有兩種實現方式。