[英]Method getParcelableExtra() returns null when creating an intent
我有一个关于创建意图以及使用getParcelableExtra()方法将对象移交给它的问题。 该项目的目的是创建回收者视图。 如果从回收商中选择了一项,则新的意图将开始,并应显示更多详细数据。
因为数据是从外部MySQL数据库获取的,所以我将Volley用于大多数网络工作。
回收器是在Volley onResponse()方法内部实现的,该方法在应用程序启动时(onCreate)首先调用。 在此之前,一切正常,回收站已正确加载并显示。
public class UserAreaActivity extends AppCompatActivity{
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_user_area);
initializeRecycler();
}
public void initializeRecycler() {
operations.getFoodFromDB(getFoodID(), new IDatabaseOperations() {
@Override
public void onSuccess(final ArrayList<Food> food_list) {
mRecyclerView = (RecyclerView) findViewById(R.id.recyclerView);
mLayoutmanager = new LinearLayoutManager(UserAreaActivity.this);
mAdapter = new FoodAdapter(food_list);
mRecyclerView.setLayoutManager(mLayoutmanager);
mRecyclerView.setAdapter(mAdapter);
mAdapter.setOnItemClickListener(new FoodAdapter.OnItemClickListener() {
@Override
public void OnItemClick(int position) {
Intent intent = new Intent(UserAreaActivity.this, FoodProfile.class);
GETS CORRECT OBJECT----->intent.putExtra("food", food_list.get(position));
startActivity(intent);
}
});
}
});
}
}
如您所见,我为Volley onResponse方法创建了一个名为onSuccess的接口。 在此方法中,我正在创建一个onItemClickListener,而这在这里变得很丑陋。 onItemClickListener会打开该项目的更详细视图,但是方法getParcelableExtra()返回NULL。 无论我做什么,都永远不会返回Food类的对象。
public class FoodProfile extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(activity_food_profile);
Food food = getIntent().getParcelableExtra("food");<----RETURNS NULL
String price = food.getPrice();
String name = food.getName();
String rating = ((Float)food.getRating()).toString();
String imageRes = food.getmimgId();
TextView mPrice = (TextView) findViewById(R.id.Price);
mPrice.setText(price);
TextView mName = (TextView) findViewById(R.id.Name);
mName.setText(name);
TextView mRating = (TextView) findViewById(R.id.Rating);
mRating.setText(rating);
}
}
因此,putExtra()可按预期工作,并获得食物类的正确对象。 但是getParcelableExtra()每次都返回NULL。 因此,启动的意图中不会显示任何值。
食品类:
public class Food implements Parcelable {
public int id;
public String name;
public String category;
public String date;
public int vegan;
public int vegetarian;
public String price;
public String uuid;
public float rating;
public String mimgId;
public Food(int id, String name, String category, int vegan, int vegetarian, String price, String uuid, float rating, String mimgId){
this.id = id;
this.name = name;
this.category = category;
this.date = date;
this.vegan = vegan;
this.vegetarian = vegetarian;
this.price = price;
this.uuid = uuid;
this.rating = rating;
this.mimgId = mimgId;
}
protected Food(Parcel in) {
id = in.readInt();
name = in.readString();
category = in.readString();
date = in.readString();
vegan = in.readInt();
vegetarian = in.readInt();
price = in.readString();
uuid = in.readString();
rating = in.readFloat();
mimgId = in.readString();
}
public static final Creator<Food> CREATOR = new Creator<Food>() {
@Override
public Food createFromParcel(Parcel in) {
return new Food(in);
}
@Override
public Food[] newArray(int size) {
return new Food[size];
}
};
public int getId() {
return id;
}
public String getName() {
if(name != null) {
name = name.replaceAll(System.getProperty("line.separator"), (""));
}
return name;
}
public String getDate() {
return date;
}
public int isVegan() {
return vegan;
}
public int isVegetarian() {
return vegetarian;
}
public String getPrice() {
return price;
}
public String getUuid() {
return uuid;
}
public float getRating(){return rating;}
public String getmimgId() {
return mimgId;
}
@Override
public int describeContents() {
return 0;
}
@Override
public void writeToParcel(Parcel dest, int flags) {
dest.writeString(price);
dest.writeString(name);
dest.writeString(((Float)rating).toString());
dest.writeString(mimgId);
}
}
有谁知道是什么导致getParcelableExtra()返回null?
谢谢您的帮助!
正如我上面评论的, writeToParcel()
有问题。 包裹的书写和读取顺序应相同。
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