C#中List用法
I've been looking for help on how to find objects in Generics with List.Find() method .... and ... take a look what I have found.
In the follow example, I created a simple class:
public class Person
{
private int _id;
private string _name;
public int ID { get{ return _id;} set{ _id = value;}}
public int Name { get{ return _name;} set{ _name= value;}}
public Person(int id, string name)
{
_id = id;
_name = name;
}
}
In the example, there's a simple class with two private attributes. Now we're going to create a typed List of this object and take advantage of the Find() method
public void CreateAndSearchList()
{
//create and fill the collection
List<Person> myList = new List<Person>();
myList.Add(new Person(1, "AndreySanches"));
myList.Add(new Person(2, "AlexandreTarifa"));
myList.Add(new Person(3, "EmersonFacunte"));
//find a specific object
Person myLocatedObject = myList.Find(delegate(Person p) {return p.ID == 1; });
}
备注：在list和array集合中搜索元素经常使用该方法，主要技术是泛型委托
list用法注意：如果增加一个对象，必须重新new一个对象，看下面的例子：
person p=new pewson();
for(int i=0;i<5;i++)
{
p.ID=i;
p.Name="xxxx";
list.add(p);
}
for(int i=0;i<5;i++)
{
person p=new person();
p.ID=i;
p.Name="xxxx";
list.add(p);
}
上面有区别吗？在输出list的值是有区别了，第一个list里面存放的都是一样的，结果和最后一个一样，都是同一个人对象，第二个list达到预期的效果，存储不同的人对象。这是为什么？原因很简单，一个list对象中存储的都是对一个共有的对象进行引用，所以以最后改变的值为准。
对象的排序：本文主要阐述对存储datatable的list进行按TableName排序
1、新建一个sort类
public class SceneSort:IComparer<DataTable>
{
public int Compare(DataTable obj1, DataTable obj2)
{
int tableNameLength1;
int tableNameLength2;
if (obj1 == null)
{
if (obj2 == null)
return 0;
else
return -1;
}
else
{
if (obj2 == null)
return 1;
else
{
tableNameLength1=obj1.TableName.Length;
tableNameLength2=obj2.TableName.Length;
if (Convert.ToInt32(obj1.TableName.Substring(2,tableNameLength1-2))>Convert.ToInt32(obj2.TableName.Substring(2,tableNameLength2-2)))
return 1; //大于返回1
else if (Convert.ToInt32(obj1.TableName.Substring(2,tableNameLength1-2))<Convert.ToInt32(obj2.TableName.Substring(2,tableNameLength2-2)))
return -1; //小于返回-1
else
return 0; //相等返回0
}
}
}
2 排序：
List<DataTable> ldt = new List<DataTable>();
SceneSort ss=new SceneSort ();
tablelist.sort(ss);即可对list进行排序；
I've been looking for help on how to find objects in Generics with List.Find() method .... and ... take a look what I have found.
In the follow example, I created a simple class:
代码
public
class
Person
{
private
int
_id;
private
string
_name;
public
int
ID {
get
{
return
_id;}
set
{ _id
=
value;}}
public
int
Name {
get
{
return
_name;}
set
{ _name
=
value;}}
public
Person(
int
id,
string
name)
{
_id
=
id;
_name
=
name;
}
}
In the example, there's a simple class with two private attributes. Now we're going to create a typed List of this object and take advantage of the Find() method
代码
public
void
CreateAndSearchList()
{
//
create and fill the collection
List
<
Person
>
myList
=
new
List
<
Person
>
();
myList.Add(
new
Person(
1
,
"
AndreySanches
"
));
myList.Add(
new
Person(
2
,
"
AlexandreTarifa
"
));
myList.Add(
new
Person(
3
,
"
EmersonFacunte
"
));
//
find a specific object
Person myLocatedObject
=
myList.Find(
delegate
(Person p) {
return
p.ID
==
1
; });
}
备注：在list和array集合中搜索元素经常使用该方法，主要技术是泛型委托
list用法注意：如果增加一个对象，必须重新new一个对象，看下面的例子：
person p
=
new
pewson();
for
(
int
i
=
0
;i
<
5
;i
++
)
{
p.ID
=
i;
p.Name
=
"
xxxx
"
;
list.add(p);
}
for
(
int
i
=
0
;i
<
5
;i
++
)
{
person p
=
new
person();
p.ID
=
i;
p.Name
=
"
xxxx
"
;
list.add(p);
}
上面有区别吗？在输出list的值是有区别了，第一个list里面存放的都是一样的，结果和最后一个一样，都是同一个人对象，第二个list达到预期的效果，存储不同的人对象。这是为什么？原因很简单，一个list对象中存储的都是对一个共有的对象进行引用，所以以最后改变的值为准。
对象的排序：本文主要阐述对存储datatable的list进行按TableName排序
1、新建一个sort类
代码
public
class
SceneSort:IComparer
<
DataTable
>
{
public
int
Compare(DataTable obj1, DataTable obj2)
{
int
tableNameLength1;
int
tableNameLength2;
if
(obj1
==
null
)
{
if
(obj2
==
null
)
return
0
;
else
return
-
1
;
}
else
{
if
(obj2
==
null
)
return
1
;
else
{
tableNameLength1
=
obj1.TableName.Length;
tableNameLength2
=
obj2.TableName.Length;
if
(Convert.ToInt32(obj1.TableName.Substring(
2
,tableNameLength1
-
2
))
>
Convert.ToInt32(obj2.TableName.Substring(
2
,tableNameLength2
-
2
)))
return
1
;
//
大于返回1
else
if
(Convert.ToInt32(obj1.TableName.Substring(
2
,tableNameLength1
-
2
))
<
Convert.ToInt32(obj2.TableName.Substring(
2
,tableNameLength2
-
2
)))
return
-
1
;
//
小于返回-1
else
return
0
;
//
相等返回0
}
}
}
2 排序：
List
<
DataTable
>
ldt
=
new
List
<
DataTable
>
();
SceneSort ss
=
new
SceneSort ();
tablelist.sort(ss);即可对list进行排序；
本文来自CSDN博客，转载请标明出处：http://blog.csdn.net/cxb_wind/archive/2008/04/10/2277670.aspx