有沒有在Java中的方式進行投射幼兒到兒童

Question

所以，如果我有以下幾點：

public abstract ClassA {} 

public class ClassB extends ClassA {} 

public class ClassC extends ClassA {} 

有沒有辦法做到以下幾點：

ClassB b = new ClassB(); 
ClassC c = (ClassC)b; 

我知道你可以不能直接做，而是有沒有避免了寫，將有像c.setField1（b.getField1）每場翻譯的方式。

Answer 1

這是不可能投下孩子小時候也不是可以投一個孩子給家長，然後回到父母。於是我寫了一個通用翻譯器，將BankInstruction的一個子類的所有數據複製到另一個。

/** 
* Convert a BankInstruction Child class to another bank instruction child class 
* 
* @param incoming 
*   The incoming child class with data 
* @param clazz 
*   The class we want to convert to and populate 
* @return 
*   The class we requested with all the populated data 
*/ 
public static <I extends BankInstruction, O extends BankInstruction> O convertBankInstructionModel(final I incoming, 
                            final Class<O> clazz) { 

    // Create return data object 
    O outgoing = null; 

    // Attempt to instantiate the object request 
    try { 
     outgoing = clazz.newInstance(); 

     // Catch and log any exception thrown 
    } catch (Exception exceptThrown) { 
     exceptThrown.printStackTrace(); 
     return null; 
    } 

    // Loop through all of the methods in the class 
    for (Method method : BankInstruction.class.getMethods()) { 

     // Check if we have a set method 
     if (method.getName().substring(0, 3).equalsIgnoreCase("set")) { 

      // Create a corresponding get method 
      String getMethodName = method.getName().replace("set", "get"); 

      // Check if we have a get method for the set method variable 
      if (Arrays.toString(BankInstruction.class.getMethods()).contains(getMethodName)) { 

       // Get the method from the method name 
       Method getMethod = getMethodFromName(BankInstruction.class, getMethodName); 

       try { 

        // If we have a method proceed 
        if (getMethod != null) { 

         // Attempt to invoke the method and get the response 
         Object getReturn = getMethod.invoke(incoming); 

         // If we have a response proceed 
         if (getReturn != null) { 

          // Attempt to invoke the set method passing it the object we just got from the get 
          method.invoke(outgoing, getReturn); 

         } 

        } 

       } catch (Exception except) { 
        except.printStackTrace(); 
       } 

      } 

     } 

    } 

    // Return the found object 
    return outgoing; 

} 

可能不是最好的解決方案，但它是爲我工作。