垃圾回收（先了解以后再研究）
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;
namespace ConsoleApplication1
{
class Program
{
static void Main(string[] args)
{
////FileStream fs;
////fs.Dispose(
//Person p1;
#region 弱引用
//引用的意思就是：当一个对象没有变量引用的时候，这时就可以被垃圾回收了。
//但是接下来如果要是再想用该对象的话也是不可能的，因为即便还没有垃圾回收，但是这个对象已经无法在引用到了（虽然堆内存中，但是找不到该对象了。）
//这时，当一个对象没有任何变量引用时，我们可以使用一个WeakReference（弱引用）来保持对这个对象的“引用”，这时虽然对该对象“弱引用”了，
//但是这个对象仍然是可以被垃圾回收的，如果在下次使用这个对象的时候，该对象还没有被垃圾回收，则可以通过弱引用直接找到该对象，然后继续使用，如果已经被垃圾回收了，则需要重新创建这个对象。
//Person p = new Person();
//p.Age = 25;
//p.Name = "叶长种";
//p.Email = "[email protected]";
////p.Email...
////Person tmp = p;
////p = null;
////GC.Collect();
////p = new Person();
////p.Name = "叶长种";
////p.Age = 25;
////p.Email = "[email protected]";
#endregion
#region 通过代码来实现弱引用
Person p = new Person();
p.Name = "叶长种";
p.Age = 25;
p.Email = "[email protected]";
//弱引用
WeakReference wkReference = new WeakReference(p);
p = null;
GC.Collect();
//if (wkReference.Target != null)
//{
// object o = wkReference.Target;
//}
//假设某个时间段的时候又要使用这个对象了。
object o = wkReference.Target;
if (o != null && wkReference.IsAlive)
{
Person p1 = o as Person;
Console.WriteLine("{0} {1} {2}", p1.Name, p1.Age, p1.Email);
}
else
{
Console.WriteLine("重新创建对象吧，已经被垃圾回收了。");
}
Console.ReadKey();
#endregion
}
}
public class Person : IDisposable
{
public string Name
{
get;
set;
}
public int Age
{
get;
set;
}
public string Email
{
get;
set;
}
public void Say()
{
}
#region IDisposable 成员
public void Dispose()
{
//编写代码，调用api,
}
#endregion
}
}
集合
using System.Collections;（非泛型集合）
using System.Collections.Generic;（泛型集合）
“类似数组”集合：ArrayList，List<>
“键值对”集合（“哈希表”集合）：Hashtable,Dictionary<K,V>
“堆栈”集合：Stack,Stack<T>(LIFO)
“队列”集合：Queue,Queue<T>(LIFO)
“可排序键值对”集合
Set集合
Dictionary集合
“双向链表”集合
class Program
{
static void Main(string[] args)
{
#region ArrayList集合
//ArrayList arrList = new ArrayList();
//arrList.Add(10);
//arrList.Add("10");
//arrList.Add(new Person() { Name = "叶长种" });
//arrList.Add(99.9);
//arrList.Add(new int[] { 1, 2, 3, 4, 5 });
//arrList.AddRange(new string[] { "叶长种", "詹姆斯", "科比" });
////arrList.RemoveAt(2);//删除索引为2的集合
//for (int i = 0; i < arrList.Count; i++)
//{
// arrList.RemoveAt(i);
//} //结果为 4 8
////arrList.Clear(); //清空集合
//Console.WriteLine(arrList.Count);
//Console.WriteLine(arrList.Capacity);
//Console.ReadKey();
//string str = "叶长种";
//int n = 0;
//try
//{
// for (int i = 0; i < 30; i++)
// {
// n = i;
// str += str;
// }
//}
//catch
//{
// Console.WriteLine(n);
// Console.WriteLine(str.Length);
//}
//Console.WriteLine(str);
//Console.ReadKey();
////Array
//int[] arr = new int[] { 1, 2, 3 };
//Console.WriteLine(arr.GetType().ToString());
//Console.WriteLine(arr.GetType().BaseType.ToString());
//Console.WriteLine(arr.GetType().BaseType.BaseType.ToString());
//Console.ReadKey();
//ArrayList arrList = new ArrayList();
#region MyRegion
//arrList.Add(10);
//arrList.Add("叶长种");
//Person p1 = new Person();
//p1.Name = "詹姆斯";
//Person p2 = new Person();
//p2.Name = "科比";
//arrList.Add(p1);
//arrList.Add(p2);
//arrList.Remove(10);
//arrList.Remove(p2);
//Console.WriteLine(arrList.Count);
//Console.WriteLine(arrList.Capacity);
//Console.ReadKey();
#endregion
//Person p1 = new Person();
//p1.Name = "yzk";
//p1.Age = 18;
//p1.Email = "[email protected]";
//Person p2 = new Person();
//p2.Name = "yzk";
//p2.Age = 18;
//p2.Email = "[email protected]";
//string s1 = new string(new char[] { ‘a‘, ‘b‘, ‘c‘ });
//arrList.Add(p1);
//arrList.Add(p2);
//arrList.Add(s1);
//arrList.Remove(p2);
//arrList.Remove("abc");//这样也会把s1删掉
////arrList.ToArray() //把集合变成数组
//Console.WriteLine(arrList.Count);
//Console.ReadKey();
#endregion
#region 集合中的Sort方法
//ArrayList arrList = new ArrayList();
#region
////arrList.Add(9);
////arrList.Add(19);
////arrList.Add(3);
////arrList.Add(7);
////arrList.Add(5);
////arrList.Sort();
//arrList.Add("sk");
//arrList.Add("jk");
//arrList.Add("yzk");
//arrList.Add("nll");
//arrList.Add("yhb");
//arrList.Add("ml");
//arrList.Sort();//升序排序
//for (int i = 0; i < arrList.Count; i++)
//{
// Console.WriteLine(arrList[i]);
//}
//Console.ReadKey();
#endregion
ArrayList arrList = new ArrayList();
Person sk = new Person() { Name = "sk", Age = 18, Email = "[email protected]" };
Person jk = new Person() { Name = "jk", Age = 17, Email = "[email protected]" };
Person yzk = new Person() { Name = "yzk", Age = 16, Email = "[email protected]" };
Person yhb = new Person() { Name = "yhb", Age = 15, Email = "[email protected]" };
arrList.Add(sk);
arrList.Add(jk);
arrList.Add(yzk);
arrList.Add(yhb);
//Sort()内部只支持升序，除非自己写CompareTo方法
arrList.Sort();
//[a,b,c,d]
//a.CompareTo(b)
//或者另外一个解决方案是，先升序排序再调用Reverse()反转数组。来实现降序的功能。
//arrList.Reverse();
for (int i = 0; i < arrList.Count; i++)
{
Person p = arrList[i] as Person;
Console.WriteLine(p.Name);
}
Console.ReadKey();
#endregion
}
}
public class Person : IComparable
{
public string Name
{
get;
set;
}
public int Age
{
get;
set;
}
public string Email
{
get;
set;
}
#region IComparable 成员
public int CompareTo(object obj)
{
Person p = obj as Person;
return this.Age - p.Age;
}
#endregion
}
集合排序ICompare接口使用
class Program
{
static void Main(string[] args)
{
ArrayList arrList = new ArrayList();
Person sk = new Person() { Name = "skk", Age = 18, Email = "[email protected]" };
Person jk = new Person() { Name = "jk", Age = 17, Email = "[email protected]" };
Person yzk = new Person() { Name = "yzkk", Age = 16, Email = "[email protected]" };
Person yhb = new Person() { Name = "yhbbbbbb", Age = 15, Email = "[email protected]" };
arrList.Add(sk);
arrList.Add(jk);
arrList.Add(yzk);
arrList.Add(yhb);
//arrList.Sort(new SortByAgeAsc());
arrList.Sort(new SortByNameAsc());
for (int i = 0; i < arrList.Count; i++)
{
Console.WriteLine(((Person)arrList[i]).Name);
}
Console.ReadKey();
//1.按照年龄降序排序
//2.按照姓名升序排序
}
}
public class SortByAgeAsc : IComparer
{
#region IComparer 成员
public int Compare(object x, object y)
{
Person px = x as Person;
Person py = y as Person;
return px.Age - py.Age;
}
#endregion
}
public class SortByNameAsc : IComparer
{
#region IComparer 成员
public int Compare(object x, object y)
{
Person px = x as Person;
Person py = y as Person;
return px.Name.Length - py.Name.Length;
}
#endregion
}
public class Person
{
public string Name
{
get;
set;
}
public int Age
{
get;
set;
}
public string Email
{
get;
set;
}
}
.Net基础加强05
时间： 2024-11-09 00:56:40