【c#】构造函数执行序列

不念不忘少年蓝@ 2022-06-12 05:24 156阅读 0赞

<table style="border-collapse:collapse; width:1324px"> 
 <tbody> 
  <tr> 
   <td style="border:1px solid rgb(204,204,204); padding:8px; width:99.92447129909365%"> 1.构造函数执行序列</td> 
  </tr> 
  <tr> 
   <td style="border:1px solid rgb(204,204,204); padding:8px"> 
    <ul> 
     <li>为了实例化派生的类，必须实例化它的基类，而实例化它的基类，又要实例化基类的基类，一直实例化到System.Object（所有类的根）为止</li> 
     <li>无论使用什么实例化一个类，总是先调用System.Object.Object()</li> 
     <li>无论派生类使用什么构造函数，只要没有明确指定，基类就调用默认构造函数</li> 
    </ul> 
    <div> 
     <br> 
    </div> 
    <div>
      执行顺序： 
    </div> 
    <div> 
     <span style="color:rgb(255,70,53)">基类的根(System.Object.Object()) &nbsp;--&gt; 基类 --&gt; 派生类</span> 
    </div> 
    <div> 
     <span style="color:rgb(255,70,53)"><br> </span> 
    </div> 
    <div>
      例： 
    </div> 
    <div> 
     <br> 
    </div> 
    <div style="padding:8px; font-family:Monaco,Menlo,Consolas,'Courier New',monospace; color:rgb(51,51,51); background-color:rgb(251,250,248)"> 
     <div>
       public class MyBaseClass 
     </div> 
     <div>
       { 
     </div> 
     <div>
       &nbsp; &nbsp; Public MyBaseClass() 
     </div> 
     <div>
       &nbsp; &nbsp; { 
     </div> 
     <div>
       &nbsp; &nbsp; } 
     </div> 
     <div>
       &nbsp; 
     </div> 
     <div>
       &nbsp; &nbsp; Public MyBaseClass(int i) 
     </div> 
     <div>
       &nbsp; &nbsp; { 
     </div> 
     <div>
       &nbsp; &nbsp; } 
     </div> 
     <div>
       } 
     </div> 
     <div> 
      <br> 
     </div> 
     <div>
       public class MyDerivedClass：MyBaseClass 
     </div> 
     <div>
       { 
     </div> 
     <div>
       &nbsp; &nbsp; public MyDerivedClass() 
     </div> 
     <div>
       &nbsp; &nbsp; { 
     </div> 
     <div>
       &nbsp; &nbsp; } 
     </div> 
     <div>
       &nbsp; &nbsp; public MyDerivedClass(int i) 
     </div> 
     <div>
       &nbsp; &nbsp; { 
     </div> 
     <div>
       &nbsp; &nbsp; } 
     </div> 
     <div>
       &nbsp; &nbsp; public MyDerivedClass(int i,int j) 
     </div> 
     <div>
       &nbsp; &nbsp; { 
     </div> 
     <div>
       &nbsp; &nbsp; } 
     </div> 
     <div>
       } 
     </div> 
    </div> 
    <div> 
     <br> 
    </div> 
    <ol> 
     <li>使用下面语句实例化MyDerivedClass</li> 
    </ol> 
    <div> 
     <br> 
    </div> 
    <div style="padding:8px; font-family:Monaco,Menlo,Consolas,'Courier New',monospace; color:rgb(51,51,51); background-color:rgb(251,250,248)">
      MyDerivedClass myObj=new MyDerivedClass(); 
     <br> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div>
      构造函数执行顺序如下： 
    </div> 
    <div> 
     <br> 
    </div> 
    <div>
      （1）执行System.Object.Object() 
    </div> 
    <div> 
     <br> 
    </div> 
    <div>
      （2）执行MyBaseClass.MyBaseClass() 
    </div> 
    <div> 
     <br> 
    </div> 
    <div>
      （3）执行MyDerivedClass.MyDerivedClass() 
    </div> 
    <div> 
     <br> 
    </div> 
    <div>
      &nbsp; &nbsp; &nbsp;2. 如果用如下语句实例化 
    </div> 
    <div> 
     <br> 
    </div> 
    <div style="padding:8px; font-family:Monaco,Menlo,Consolas,'Courier New',monospace; color:rgb(51,51,51); background-color:rgb(251,250,248)">
      MyDerivedClass myObj=new MyDerivedClass(5); 
     <br> 
    </div> 
    <div>
      构造函数执行顺序如下： 
    </div> 
    <div> 
     <br> 
    </div> 
    <div>
      （1）执行System.Object.Object() 
    </div> 
    <div> 
     <br> 
    </div> 
    <div>
      （2）执行MyBaseClass.MyBaseClass() 
    </div> 
    <div> 
     <br> 
    </div> 
    <div>
      （3）执行MyDerivedClass.MyDerivedClass(5) 
    </div> 
    <div> 
     <br> 
    </div> </td> 
  </tr> 
  <tr> 
   <td style="border:1px solid rgb(204,204,204); padding:8px"> 
    <div> 
     <strong>执行基类的非默认构造函数</strong> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="color:rgb(255,70,53)">base 关键字</span> 
    </div> 
    <div style="padding:8px; font-family:Monaco,Menlo,Consolas,'Courier New',monospace; color:rgb(51,51,51); background-color:rgb(251,250,248)"> 
     <div>
       publicclass MyDerivedClass：MyBaseClass 
     </div> 
     <div>
       { 
     </div> 
     <div> 
      <br> 
     </div> 
     <div>
       &nbsp; &nbsp; public MyDerivedClass() 
     </div> 
     <div>
       &nbsp; &nbsp; { &nbsp; 
     </div> 
     <div> 
      <br> 
     </div> 
     <div>
       &nbsp; &nbsp; } 
     </div> 
     <div> 
      <br> 
     </div> 
     <div>
       &nbsp; &nbsp; public MyDerivedClass(int i) 
     </div> 
     <div>
       &nbsp; &nbsp; { &nbsp; 
     </div> 
     <div> 
      <br> 
     </div> 
     <div>
       &nbsp; &nbsp; } 
     </div> 
     <div> 
      <br> 
     </div> 
     <div>
       &nbsp; &nbsp; public MyDerivedClass(int i,int j) ： 
      <span style="color:rgb(255,70,53)">base(i)</span> 
     </div> 
     <div>
       &nbsp; &nbsp; { 
     </div> 
     <div> 
      <br> 
     </div> 
     <div>
       &nbsp; &nbsp; } 
     </div> 
     <div>
       } 
     </div> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div>
      使用如下语句实例化 
    </div> 
    <div> 
     <br> 
    </div> 
    <div style="padding:8px; font-family:Monaco,Menlo,Consolas,'Courier New',monospace; color:rgb(51,51,51); background-color:rgb(251,250,248)">
      MyDerivedClass myObj=new MyDerivedClass(3， 5); 
     <br> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div>
      构造函数执行顺序如下： 
    </div> 
    <div> 
     <br> 
    </div> 
    <div>
      （1）执行System.Object.Object() 
    </div> 
    <div> 
     <br> 
    </div> 
    <div>
      （2）执行MyBaseClass.MyBaseClass(int i) 
    </div> 
    <div> 
     <br> 
    </div> 
    <div>
      （3）执行MyDerivedClass.MyDerivedClass(int i, int j) 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="color:rgb(255,70,53)">this关键字</span> 
    </div> 
    <div style="padding:8px; font-family:Monaco,Menlo,Consolas,'Courier New',monospace; color:rgb(51,51,51); background-color:rgb(251,250,248)"> 
     <div>
       public class MyDerivedClass：MyBaseClass 
     </div> 
     <div> 
      <br> 
     </div> 
     <div>
       { 
     </div> 
     <div>
       &nbsp; &nbsp; public MyDerivedClass(): 
      <span style="color:rgb(255,70,53)">this(5,6)</span> 
     </div> 
     <div>
       &nbsp; &nbsp; { 
     </div> 
     <div> 
      <br> 
     </div> 
     <div>
       &nbsp; &nbsp; } 
     </div> 
     <div>
       &nbsp; &nbsp; public MyDerivedClass(int i) 
     </div> 
     <div>
       &nbsp; &nbsp; { 
     </div> 
     <div> 
      <br> 
     </div> 
     <div>
       &nbsp; &nbsp; } 
     </div> 
     <div>
       &nbsp; &nbsp; public MyDerivedClass(int i,int j)：base(i) 
     </div> 
     <div>
       &nbsp; &nbsp; { 
     </div> 
     <div> 
      <br> 
     </div> 
     <div>
       &nbsp; &nbsp; } &nbsp; 
     </div> 
     <div>
       } 
     </div> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div>
      使用如下语句实例化 
    </div> 
    <div> 
     <br> 
    </div> 
    <div style="padding:8px; font-family:Monaco,Menlo,Consolas,'Courier New',monospace; color:rgb(51,51,51); background-color:rgb(251,250,248)">
      MyDerivedClass myObj=new MyDerivedClass(); 
     <br> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div>
      构造函数执行顺序如下： 
    </div> 
    <div> 
     <br> 
    </div> 
    <div>
      （1）执行System.Object.Object() 
    </div> 
    <div> 
     <br> 
    </div> 
    <div>
      （2）执行MyBaseClass.MyBaseClass(int i) 
    </div> 
    <div> 
     <br> 
    </div> 
    <div>
      （3）执行MyDerivedClass.MyDerivedClass(int i, int j) 
    </div> 
    <div> 
     <br> 
    </div> 
    <div>
      （4）执行MyDerivedClass.MyDerivedClass() 
    </div> </td> 
  </tr> 
 </tbody> 
</table>