ImageViews在更改/重新加载/旋转片段后未渲染

Question

我在片段类中遇到了一个奇怪的错误：imageViews"消失"；如果我旋转/重新加载视图。根据我的理解，旋转/重新加载会破坏视图并重新创建它，因此局部变量和局部视图元素可能无法保留。然而，我已经制作了一个手动按钮，在我单击它后，它应该再次手动渲染图像，但即使我手动重置了imageResource或imageBackground资源，ImageViews也不会出现。请注意，这些图像视图是可绘制的动画。以下是我的大部分代码：

@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
View rootView = inflater.inflate(R.layout.fragment_home, container, false);
mView = rootView;  //mView is global
return rootView;
}
@Override
public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
Log.d("gnereed id", "id is "+R.id.generate_button);
final Button generate_button = getView().findViewById(R.id.generate_button);
if ( bottleMap == null ) bottleMap = new Hashtable();

// the code sets all images to invisible onCreate
// their visibility will be changed when a bottle is "created" 
ImageView[] bottles = new ImageView[7];
for (int i = 0; i < bottleAry.length; i++){
bottles[i] = getView().findViewById(bottleAry[i]);
bottles[i].setVisibility(View.GONE);
}

// this is a button that generates a new bottle and manually refreshes all previous bottle
// If fragment has not been reloaded/rotated then everything works here
// after fragment reloads, new bottles can be generated but old bottles do not re-render.
generate_button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Bottle bottle = new Bottle("123", bottleList.size());
bottle.setVisible();
bottleList.add(bottle);
Log.e(" mView : ", mView.toString());
// for all bottles created, re-render them
for (int i = 0; i < bottleList.size(); i ++) {
bottleList.get(i).reRender();
}
}
});
}
public class Bottle{
String message;
ImageView bottleLocation;
int imageSrc;
int avail_index;
int bottle_index;
int locationID;
AnimationDrawable bottleAnimation;
public Bottle(String msg, int bottle_index){
message = msg;
this.bottle_index = bottle_index;
locationID = getRandomBottleLocation();
bottleLocation =  getView().findViewById(locationID);
Log.e(" old View : ", getView().toString());
// sets the image source and sets visible, lastly start animation
imageSrc = getRandomBottleImg();
bottleLocation.setBackgroundResource(imageSrc);
bottleMap.put(Integer.toString(locationID), imageSrc);
bottleAnimation = (AnimationDrawable) bottleLocation.getBackground();
bottleAnimation.start();
bottleLocation.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
startActivity(new Intent(getActivity(), ViewBottleActivity.class));
availableLocation[avail_index] = false;
bottleMap.remove(Integer.toString(locationID));
bottleAnimation.stop();
bottleLocation.setVisibility(View.GONE);
bottleList.remove(bottle_index);
}
});
}
public int getRandomBottleImg(){
int bottle;
Random rand = new Random();
bottle = imgAry[rand.nextInt(imgAry.length)];
return bottle;
}
public int getRandomBottleLocation(){
int location;
Random rand = new Random();
avail_index = rand.nextInt(bottleAry.length);
while (availableLocation[avail_index]){
avail_index = rand.nextInt(bottleAry.length);
}
location = bottleAry[avail_index];
availableLocation[avail_index] = true;
return location;
}
public void reRender(){
Log.e("location ID is:" , Integer.toString(this.locationID));
bottleLocation =  mView.findViewById(this.locationID);
Log.e("ImageView is:" , bottleLocation.toString());
imageSrc = getRandomBottleImg();
bottleLocation.setBackgroundResource(imageSrc);
bottleAnimation = (AnimationDrawable) bottleLocation.getBackground();
bottleAnimation.stop();
bottleAnimation.start();
this.setVisible();
}
public void setVisible(){
bottleLocation.setVisibility(View.VISIBLE);
}

Answer 1

我解决了这个问题。我学到的是你不能使用

View.findViewByID(viewID)

onViewCreated((之外。注意到我是如何在onViewCreated((中实现reRender((函数但它不起作用的吗？结果是mView.findViewByID(viewID(实际上是在onViewCreated((的OUTSIDE执行的，尽管我是从WITHINE调用函数的。

是的，该行将被执行，但在检查时，mView.findViewByID(viewID(将在从onViewCreated((内部调用时和从onViewCreate((调用的函数调用时返回两个不同的对象。

这是非常违反直觉的，尤其是对于我们这些被教导部署DRY(不要重复自己(原则的人来说。修复方法只是简单地不编写用于处理View的外部函数。