mark: https://www.cnblogs.com/zzy2740/archive/2005/09/20/240808.html
C#中的abstract 類和方法!!!
using System;
abstract class MyAbs
{
public void NonAbMethod()
{
Console.WriteLine("Non-Abstract Method");
}
}
class MyClass : MyAbs
{
}
class MyClient
{
public static void Main()
{
//MyAbs mb = new MyAbs();//不能實例化
MyClass mc = new MyClass();
mc.NonAbMethod();
}
}
一個抽象類可以包含abstract方法，也可包含實例化方法，但繼承類（非抽象）必須實現abstract方法
using System;
abstract class MyAbs
{
public void NonAbMethod()
{
Console.WriteLine("Non-Abstract Method");
}
public abstract void AbMethod(); // 抽象方法，只有聲明，沒有實現
}
class MyClass : MyAbs//必須實現抽象方法
{
public override void AbMethod()
{
Console.WriteLine("Abstarct method");
}
}
class MyClient
{
public static void Main()
{
MyClass mc = new MyClass();
mc.NonAbMethod();
mc.AbMethod();
}
}
當然繼承類也可以是抽象的
using System;
abstract class MyAbs
{
public abstract void AbMethod1();
public abstract void AbMethod2();
}
//抽象繼承類不必全部實現抽象方法，部分實現便可
abstract class MyClass1 : MyAbs
{
public override void AbMethod1()
{
Console.WriteLine("Abstarct method #1");
}
}
class MyClass : MyClass1
{
public override void AbMethod2()
{
Console.WriteLine("Abstarct method #2");
}
}
class MyClient
{
public static void Main()
{
MyClass mc = new MyClass();
mc.AbMethod1();
mc.AbMethod2();
}
}
抽象類可以繼承自非抽象類
using System;
class MyClass1
{
public void Method1()
{
Console.WriteLine("Method of a non-abstract class");
}
}
abstract class MyAbs : MyClass1
{
public abstract void AbMethod1();
}
class MyClass : MyAbs//實例類必須實現抽象方法
{
public override void AbMethod1()
{
Console.WriteLine("Abstarct method #1 of MyClass");
}
}
class MyClient
{
public static void Main()
{
MyClass mc = new MyClass();
mc.Method1();
mc.AbMethod1();
}
}
抽象類可以實現接口
using System;
interface IInterface
{
void Method1();
}
abstract class MyAbs : IInterface
{
public void Method1()
{
Console.WriteLine("Method implemented from the IInterface");
}
}
class MyClass : MyAbs
{
}
class MyClient
{
public static void Main()
{
MyClass mc = new MyClass();
mc.Method1();
}
}
最后需要注意的是抽象類不能聲明為sealed,這兩個語義是沖突的。抽象方法不必（也不能）聲明為virtual，因為它缺省隱含就為virtual!
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;
namespace ConsoleApp3_1._10_lock_20191107
{
class Program
{
static void Main(string[] args)
{
Console.WriteLine("Incorrect counter");
var c = new Counter();
var t1 = new Thread(() => TestCounter(c));
var t2 = new Thread(() => TestCounter(c));
var t3 = new Thread(() => TestCounter(c));
t1.Start();
t2.Start();
t3.Start();
t1.Join();
t2.Join();
t3.Join();
Console.WriteLine("Total count: {0}", c.Count);
Console.WriteLine("--------------");
Console.WriteLine("Correct counter");
var c1 = new CounterWithLock();
t1 = new Thread(() => TestCounter(c1));
t2 = new Thread(() => TestCounter(c1));
t3 = new Thread(() => TestCounter(c1));
t1.Start();
t2.Start();
t3.Start();
t1.Join();
t2.Join();
t3.Join();
Console.WriteLine("Total count: {0}", c1.Count);
Console.ReadLine();
}
static void TestCounter(CounterBase c)
{
for(int i = 0; i < 10000; i++)
{
c.Increment();
c.Decrement();
}
}
class Counter : CounterBase
{
public int Count { get; private set; }
public override void Increment()
{ Count++; }
public override void Decrement()
{ Count--; }
}
class CounterWithLock : CounterBase
{
private readonly object _syncRoot = new Object();
public int Count { get; private set; }
public override void Increment()
{
lock (_syncRoot)
{
Count++;
}
}
public override void Decrement()
{
lock (_syncRoot)
{
Count--;
}
}
}
abstract class CounterBase
{
public abstract void Increment();
public abstract void Decrement();
}
}
}
當主線程啟動時，創建了一個Counter類的對象。該類定義了一個遞增和遞減的計數器，啟動了三個線程，三個線程共享同一個counter實例，在同一個周期中進行一次遞增和一次遞減。