動態添加多個視圖和類到當前視圖

Question

我有興趣使用用戶定義數量的相同視圖填充屏幕/活動。每個視圖將具有完全相同的佈局：幾個TextViews和幾個按鈕。問題是每個按鈕都將控制每個TextView將顯示的內容。

我想實現它的方式是有一個XML和一個Java類。然後取決於用戶輸入的數字，用許多相同的視圖填充屏幕（使用for循環）。問題是，它可以做到嗎？怎麼樣？我是否以正確的方式思考它？

請幫助任何輸入或想法，代碼示例將很好。

Answer 1

當然

是可以做到的。

我認爲最簡單的爲您的情況，再加上那麼你就可以輕鬆地擴展，是創建照顧一些輔助功能：

1創建一個空的屏幕 2）屏幕 創建一個按鈕） 3）屏幕 創建一個TextView終於 4）創建屏幕，並填充它

你必須決定正確的根元素爲您的看法，取決於孩子機務佈局需要。爲了簡單起見，讓我們選擇一個LinearLayout，但是對於RelativeLayout或TableLayout，這個例子是一樣的，它只是改變了當你添加元素時，你必須使用額外的參數來正確放置它們。

請注意，創建空自定義視圖的函數返回ViewGroup（「所有佈局都來自」）。這樣，您總是使用ViewGroups，只需在createCustomView中定義一次屏幕布局類型即可。所以，你可以改變屏幕的類型就在那裏，和代碼的其餘部分將工作...

這裏是你的靈感一些代碼：

private ViewGroup createCustomView(Context context) { 

    LinearLayout myCoolNewView=new LinearLayout(context); // or RelativeLayout, etc.. 
    return myCoolNewView; 
} 

private Button createButton(Context context, String buttonText) { 
    Button newButton=new Button(context); 
    newButton.setText(buttonText); 
    return newButton; 
} 

private TextView createText(Context context, String initialText) { 
    TextView newText=new TextView(context); 
    newText.setText(buttonText); 
    return newText; 
} 

private ViewGroup createScreen(Context context, int numberOfButtons, int numberOfTextfields) { 

    ViewGroup newScreen=createCustomView(context); 
    TextView[] textViews=new TextView[numberOfTextFields]; 

    for (int i=0; i<numberOfTextfields; i++) { 
      textViews[i]=createText(context, "hi i am text "+i); 
      newScreen.addView(textViews[i]); // you ideally provide here layoutparams to properly place your buttons 

    } 
    for (int j=0; i<numberOfButtons; j++) { 
      Button button=createButton(context, "hi i am button "+j); 
      button.setOnClickListener(new OnClickListener() { 
       public void onClick (View clickedView) { 
        // here you have a button keypress and you know all the textviews 
        textView[i%j].setText("hey you pressed me"); 
       } 
      }); 
      newScreen.addView(button); 
    } 
    return newScreen; 
} 

所以現在你可以：

ViewGroup screen1=createScreen(context, 10, 10); 
ViewGroup screen2=createScreen(context, 5, 3); 
ViewGroup screen3=createScreen(context, 2, 5); 

和屏幕添加到父佈局，到ViewFlipper，到ViewSwitcher，等...這樣的：

ViewGroup parentLayoutOfAllScreens=findViewById(R.id.root_of_screens); 
parentLayoutOfAllScreens.addView(screen1); 
parentLayoutOfAllScreens.addView(screen2); 
parentLayoutOfAllScreens.addView(screen3); 

在XML中，您只需創建根佈局，並將其命名爲root_of_screens ...

好的編碼！我想在上面的代碼中會出現一些錯誤，只需在這裏輸入它，但我希望你能明白並調整它以適應你的需求！

編輯：v2.0：擴展視圖 創建一個名爲「MyCoolScreen」的新.java。Java的」或任何名義，在您的活動（爲簡單起見）相同的文件夾：

package ........ 
public class MyCoolScreen extends LinearLayout { 

    /** Now every view holds its own buttons, and they are private, it's good for encapsulating */ 
    private TextView[] mTextViews; // <-- as a convention, members should start with "m" 
    private Button[] mButtons; 
    private UserPressedButtons mUserPressedButtonsListener; // See below 

    /** The following constructors must always be present for a custom view, and must always call super */ 
    public MyCoolScreen(Context context) { 
     // This is the constructor you will use when creating your view programmatically 
     super(context); 
    } 

    public MyCoolScreen(Context context, AttributeSet attrs) { 

     // This is the constructor Android calls when you include your custom view in an XML 
     // You can do this too!! 
     // The ATTRS will then include your numberofbuttons and numberoftextfields from the XML 
     // this is beyond the example, but read about it, it's interesting 

     super(context, attrs); // this MUST ALWAYS be here for custom views, or they will not work. 
           // it tells the parent view to continue the construction. 
    } 

    public MyCoolScreen(Context context, AttributeSet attrs, int defStyle) { 
     // Another constructor Android calls from the XML 
     super(context, attrs, defStyle); 
    } 


    /** We create an "init" method to initialize this view from outside */ 
    public void init(int numberOfTextViews, int numberOfButtons) { 
     createScreen(numberOfTextViews, numberOfButtons); 
    } 


    /** This is the same */ 
    private Button createButton(Context context, String buttonText) { 
     Button newButton=new Button(context); 
     newButton.setText(buttonText); 
     return newButton; 
    } 

    /** This is the same */ 
    private TextView createText(Context context, String initialText) { 
     TextView newText=new TextView(context); 
     newText.setText(buttonText); 
     return newText; 
    } 

    /** We tweak this function so it doesnt return a view, but rather fills up this one :) */ 

    private void createScreen(int numberOfButtons, int numberOfTextfields) { 

     ViewGroup newScreen=this; // It's this view the one we gonna fill up! 
     mTextViews=new TextView[numberOfTextfields]; 
     mButtons=new Button[numberOfButtons]; 
     Context context=getContext(); // Views always know their context after constructed 

     for (int i=0; i<numberOfTextfields; i++) { 
       mTextViews[i]=createText(context, "hi i am text "+i); 
       newScreen.addView(textViews[i]); // you ideally provide here layoutparams to properly place your buttons 
     } 

     for (int j=0; i<numberOfButtons; j++) { 
       Button button=createButton(context, "hi i am button "+j); 
       button.setId(j); 
       button.setOnClickListener(new OnClickListener() { 
        public void onClick (View clickedView) { 
         // here you have a button keypress and you know all the textviews 
         if (mUserPressedButtonsListener!=null) mUserPressedButtonsListener.OnButtonPressed(j); 
         textView[i%j].setText("hey you pressed me"); 
        } 
       }); 
       mButtons[j]=button; 
       newScreen.addView(button); 
     } 
    } 

    public interface UserPressedButtons { 
     public void OnButtonPressed(int buttonNumber); 
    } 

    public void setUserPressedButtonsListener (UserPressedButtons listener) { 
     mUserPressedButtonsListener=listener; 
    } 
} 

好了，所以現在要利用這一點，在你的活動，你可以這樣做：

import ....... .MyCoolScreen; 
    import ....... .MyCoolScreen.UserPressedButtons; 

    . 
    . 
    . 

    MyCoolScreen screen1=new MyCoolScreen(context); 
    screen1.init(5,5); // initializes the screen. 

    myRootLayout.addView(screen1); 

什麼很酷關於這一點，現在功能被完全封裝在你的自定義視圖中，並且它駐留在另一個.java中，所以你的活動代碼非常乾淨，甚至可以擴展視圖功能而不會使它變得更難看。爲您的視圖創建接口和偵聽器的常見做法與外界溝通，因此，例如，我們可以這樣做：

 screen1.setUserPressedButtonsListener(new MyCoolScreen.UserPressedButtons() { 
     @Override 
     public void OnButtonPressed (int number) { 
       // you know the user pressed button "number", and you can do stuff about it without 
       // having to include it inside the MyCoolScreen class. Of course in your example you 
       // don't need this at the moment, because the View will modify its textfield, but suppose 
       // one of the buttons is "rocket launch" , that is something you will handle at the activity level, ie. 

       if (number==ROCKET_LAUNCH) RocketLauncher.setTarget(10,10).launch(); // Your MyCoolScreen doesnt know how to launch rockets, but your activity maybe yes... 

     } 
    }); 

你可以做各種很酷的事情與你的新的自定義視圖。例如，你可以定義：

 @Override 
    public void OnDraw(Canvas c) { 
      c.drawEllipse ... 
      c.drawRectangle .... 
    } 

而且你可以畫出圓，線，等等...在你的文本框&按鈕:)對於這個工作，你必須把

setWillNotDraw(false) on the constructor. 

有可能是錯誤，只需在此鍵入代碼，但我希望它能幫助你！

Answer 2

Add and Remove Views in Android Dynamically?

這將有助於您最...