使用策略模式的示例

Question

我目前遇到了一个问题，我有一个名为＆＃39; PopupWindow＆＃39;它初始化了一个AlertDialog.Builder并将其显示给用户。但是我有两个子类叫做CallInitializePopup＆＃39;和＆＃39; CallReinitializePopup＆＃39;。我想＆＃34;外包＆＃34;这些子类的输入监听器（onClick），并且具有代码所在的子类的单独代码。

PopupWindow片段：

alert = new AlertDialog.Builder(mainActivity);

    //'setTitle' simply sets the title of the popup
    //'setMessage' sets the description, usually a short instruction on what the user should enter
    alert.setTitle(POPUP_LOGIN_TITLE);
    alert.setMessage(POPUP_LOGIN_TEXT);

    //Initialize EditTexts that will populate our popup and set the hints for each
    stockSymbolEditText = new EditText(mainActivity);
    stockSymbolEditText.setHint(STOCK_SYMBOL_HINT);
    stockPriceEditText = new EditText(mainActivity);
    stockPriceEditText.setHint(STOCK_PRICE_HINT);

    //These TextViews are only there to give the user guidance on what to include regarding the Spinners(since the Spinners doesn't include hints)
    buyOrSellTextView = new TextView(mainActivity);
    buyOrSellTextView.setText("  Alert - buy or sell");

LinearLayout.LayoutParams layoutParams = new LinearLayout.LayoutParams(LinearLayout.LayoutParams.FILL_PARENT, LinearLayout.LayoutParams.WRAP_CONTENT);
    layoutParams.setMargins(0, 0, 0, 35);

    LinearLayout layout = new LinearLayout(mainActivity);
    layout.setOrientation(LinearLayout.VERTICAL);
    layout.addView(stockSymbolEditText, layoutParams);
    layout.addView(stockPriceEditText, layoutParams);
    //layout.addView(updateIntervalTextView);
    //layout.addView(updateIntervalSpinner);
    layout.addView(buyOrSellTextView);
    layout.addView(buySellSpinner);
    alert.setView(layout);

    //Finally we show the popup
    alert.show();

我在子类中的第一个OnClickListener方法：

private void setInputListener()
{
    Log.d("setInputListener", "called");

    alert.setPositiveButton("Set Alert", new DialogInterface.OnClickListener() {
        public void onClick(DialogInterface dialog, int whichButton) {
            //Store the values in current variables
            stockSymbol = stockSymbolEditText.getText().toString();
            stockPrice = stockPriceEditText.getText().toString();
            //String selectedInterval = updateIntervalSpinner.getSelectedItem().toString();
            buyOrSell = buySellSpinner.getSelectedItem().toString();

            Log.d("Alert dialog submitted", "stockSymbol: " + stockSymbol + " - " + "stockPrice: " + stockPrice + " - " + "buyOrSell: " + buyOrSell);


            //Only call 'AssignStockCall()' once stockSymbol, stochPrice, and buyOrSell are initialized in the onClick method
            //Create a new StockCall with the new info the user included
            AssignNewStockCall();
        }
    });

    //With 'setNegativeButton' we don't want to do anything, the user doesn't want to add a new stock call
    alert.setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
        public void onClick(DialogInterface dialog, int whichButton) {
            //Canceled
        }
    });
}

第一种方法没有显示任何按钮，如果我要猜测是因为我们在另一个类之后初始化inputListener，而不是初始化AlertDialog.Builder时。

第二种方法：

    //These onClick classes are used by the PopupWindow class, they are assigned to the specific button by supplying a new instance of the classes
final class CancelOnClickListener implements
        DialogInterface.OnClickListener
{
    public void onClick(DialogInterface dialog, int which)
    {
        Log.d("onClick", "Cancel");
    }
}

final class SetAlertOnClickListener implements
        DialogInterface.OnClickListener
{
    public void onClick(DialogInterface dialog, int which)
    {
        Log.d("onClick", "Set Alert");
    }
}

这种方法不适用于超级课程，因为超级课程需要知道它是否是一个“CallInitializePopup”＆＃39; CallInitializePopup＆＃39;或者“CallReinitializePopup”＃39;超级和次级之间没有这种沟通。

非常感谢任何帮助！

Answer 1

如果你不改变你的编码风格，你将来会遇到很多这样的问题。您应该首先学习面向对象编程的SOLID原则。 https://en.wikipedia.org/wiki/SOLID_%28object-oriented_design%29然后研究设计模式。 Derek Banas youtube频道得到了帮助，因为他非常清楚地解释了设计模式。在您的情况下，您违反了开放封闭原则（来自SOLID原则）。超类不应该依赖于子类。在你的情况下，我根本不会使用继承。如果您需要对同一操作执行不同的操作，请使用策略或状态设计模式。

使用策略模式的示例

class PopUpWindow implements DialogInterface.OnClickListener
{
    /**
    *
    *
    *    other code
    *
    **/

    /** You don't need two different listers. Use same listener since 
        you can determine which button has been pressed from *int which*  **/

    alert.setPositiveButton(this);   
    alert.setNegativeButton(this);

    interface Strategy
    {
        public void doWork();
    }

    @Override
    public void onClick(DialogInterface dialog, int which)
    {
         switch(which)
         {
             case dialog.BUTTON_POSITIVE :
                   getPositiveButtonStrategy().doWork(); break;
             case dialog.BUTTON_NEGATIVE :
                   getNegativeButtonStrategy().doWork(); break;

         }
    }

    private Strategy getPositiveButtonStrategy()
    { 
        if (/** conditions to implementation NO1**/)
              return new Strategy
                         {
                            @Override
                            public void doWork()
                            {
                                /** your implementation NO1 **/
                            }
                          }
                      else return new Strategy
                                      {
                                         @Override
                                         public void doWork()
                                         {
                                            /** your implementation NO2 **/
                                         }
                                      };
              /** you can implement as much Strategies as you need **/                       
        }
    }

    private Strategy getNegativeButtonStrategy()
    { 
        if (/** conditions to implementation NO1**/)
              return new Strategy
                         {
                            @Override
                            public void doWork()
                            {
                                /** your implementation NO1 **/
                            }
                          }
                      else return new Strategy
                                      {
                                         @Override
                                         public void doWork()
                                         {
                                            /** your implementation NO2 **/
                                         }
                                      };
              /** everything in your class is available for "Strategies" **/                    
        }
    }
}

在不了解SOLID和设计模式的情况下，编写可理解，可维护，无错误的代码几乎是不可能的

Android - OnClick使用子类而不是super

1 个答案:

使用策略模式的示例