[英]How to open new activity in recyclerview with firebase database
[英]How to show RecyclerView after a new activity is created, Android Firebase
当我的主页片段通过意图使用常规按钮进入新课程时。 在新类上,当我尝试使用RecylerVie
和 Firebase 显示数据时,数据没有出现并且应用程序崩溃。
在我的 Firebase 上,节点从项目 --> 到 DataHome --> Home1。 主页 1 具有描述、方向、成分、图像、标题的属性
DataHome 也有其他名为 Home2 的节点,等等。但在这种情况下,我只是想在这个类上显示来自 Home1 的数据。
logcat 说致命异常 Main: Process: com.google.firebase.database.DatabaseException: Can't convert object of type java.lang.String to type com.example.tmrecipes.Model.DataHome
这是课程:
public class BeefSamosa extends AppCompatActivity {
FirebaseDatabase mHomeFireBaseDatabase;
RecyclerView myhomeview;
private DatabaseReference DataHomeRef;
private LinearLayoutManager mLinearLayoutManager;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_beef_samosa);
//Back Button
getSupportActionBar().setDisplayShowHomeEnabled(true);
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
getSupportActionBar().setTitle("Beef Samosa");
//Recycler View
myhomeview = findViewById(R.id.beefview);
myhomeview.setHasFixedSize(true);
//set layout as LinearLayout
myhomeview.setLayoutManager(new LinearLayoutManager(this));
//send query to firebase database
mHomeFireBaseDatabase = FirebaseDatabase.getInstance();
DataHomeRef = mHomeFireBaseDatabase.getInstance().getReference("DataHome").child("Home1");
}
@Override
public boolean onOptionsItemSelected (MenuItem item){
int id = item.getItemId();
if(id == android.R.id.home){
//ends the activity
this.finish();
}
return super.onOptionsItemSelected(item);
}
@Override
protected void onStart() {
super.onStart();
Query query = FirebaseDatabase.getInstance()
.getReference("DataHome")
.child("Home1");
FirebaseRecyclerOptions<DataHome> options =
new FirebaseRecyclerOptions.Builder<DataHome>()
.setQuery(DataHomeRef, DataHome.class)
.build();
FirebaseRecyclerAdapter<DataHome,DataHomeViewHolder> firebaseRecyclerAdapter = new FirebaseRecyclerAdapter<DataHome, DataHomeViewHolder>(options) {
@NonNull
@Override
public DataHomeViewHolder onCreateViewHolder(ViewGroup parent, int viewtype) {
final View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.activity_home_deatil, parent, false);
return new DataHomeViewHolder(view);
}
@Override
protected void onBindViewHolder(@NonNull DataHomeViewHolder holder, int position, @NonNull DataHome model) {
holder.setDetails(getApplicationContext(), model.getTitle(), model.getImage(), model.getDescription() , model.getIngredients(), model.getDirections());
}
};
firebaseRecyclerAdapter.startListening();
myhomeview.setAdapter(firebaseRecyclerAdapter);
}
//DataHomeViewHolder class
public static class DataHomeViewHolder extends RecyclerView.ViewHolder {
View mview;
public DataHomeViewHolder(@NonNull View itemView) {
super(itemView);
mview = itemView;
}
public void setDetails(Context ctx, String title, String image, String description, String ingredients , String directions) {
//Views
TextView mHomeTitle = mview.findViewById(R.id.titlewords);
ImageView mHomeImage = mview.findViewById(R.id.loading_pic);
TextView mDescriptionTitle = mview.findViewById(R.id.descriptionwords);
TextView mIngredientsTitle = mview.findViewById(R.id.ingredientwords);
TextView mDirectionsTitle = mview.findViewById(R.id.directionwords);
//Set data to views
mHomeTitle.setText(title);
mDescriptionTitle.setText(description);
mIngredientsTitle.setText(ingredients);
mDirectionsTitle.setText(directions);
Picasso.get().load(image).into(mHomeImage);
}
}
}
我的模型类是:
public class DataHome {
public String title ,image, description, ingredients, directions;
public String getTitle() {
return title;
}
public void setTitle(String title) {
this.title = title;
}
public String getImage() {
return image;
}
public void setImage(String image) {
this.image = image;
}
public String getDescription() {
return description;
}
public void setDescription(String description) {
this.description = description;
}
public String getIngredients() {
return ingredients;
}
public void setIngredients(String ingredients) {
this.ingredients = ingredients;
}
public String getDirections() {
return directions;
}
public void setDirections(String directions) {
this.directions = directions;
}
public DataHome(String title, String image, String description, String ingredients, String directions){
this.title =title;
this.image = image;
this.description = description;
this.ingredients = ingredients;
this.directions=directions;
}
}
编辑:更改后的类是:
公共类 BeefSamosa 扩展了 AppCompatActivity {
私有 FirebaseRecyclerAdapter firebaseRecyclerAdapter;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_beef_samosa);
//Back Button
getSupportActionBar().setDisplayShowHomeEnabled(true);
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
getSupportActionBar().setTitle("Beef Samosa");
RecyclerView recyclerView = findViewById(R.id.beef_view);
recyclerView.setLayoutManager(new LinearLayoutManager(this));
DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
Query query = rootRef.child("DataHome");
FirebaseRecyclerOptions<DataHome> firebaseRecyclerOptions = new FirebaseRecyclerOptions.Builder<DataHome>()
.setQuery(query, DataHome.class)
.build();
firebaseRecyclerAdapter = new FirebaseRecyclerAdapter<DataHome, DataHomeViewHolder>(firebaseRecyclerOptions) {
@Override
protected void onBindViewHolder(@NonNull DataHomeViewHolder dataHomeViewHolder, int position, @NonNull DataHome dataHome) {
dataHomeViewHolder.setDataHome(dataHome);
}
@Override
public DataHomeViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.homedetail, parent, false);
return new DataHomeViewHolder(view);
}
};
recyclerView.setAdapter(firebaseRecyclerAdapter);
}
@Override
protected void onStart() {
super.onStart();
firebaseRecyclerAdapter.startListening();
}
@Override
protected void onStop() {
super.onStop();
if (firebaseRecyclerAdapter!= null) {
firebaseRecyclerAdapter.stopListening();
}
}
@Override
public boolean onOptionsItemSelected (MenuItem item){
int id = item.getItemId();
if(id == android.R.id.home){
//ends the activity
this.finish();
}
return super.onOptionsItemSelected(item);
}
//DataHomeViewHolder class
private class DataHomeViewHolder extends RecyclerView.ViewHolder {
private TextView imagetoo, titletext, description, ingredients, directions;
DataHomeViewHolder(View itemView){
super(itemView);
imagetoo = itemView.findViewById(R.id.imagetoo);
titletext = itemView.findViewById(R.id.titletext);
description = itemView.findViewById(R.id.description);
ingredients = itemView.findViewById(R.id.ingredients);
directions = itemView.findViewById(R.id.directions);
}
void setDataHome(DataHome DataHome) {
String imageto = DataHome.getImage();
imagetoo.setText(imageto);
String titleto = DataHome.getTitle();
titletext.setText(titleto);
String descriptionto = DataHome.getDescription();
description.setText(descriptionto);
String ingredientsto = DataHome.getIngredients();
ingredients.setText(ingredientsto);
String directionsto = DataHome.getDirections();
directions.setText(directionsto);
}
}
}
您收到以下错误:
Fatal Exception Main: Process: com.google.firebase.database.DatabaseException: Can't convert object of type java.lang.String to type com.example.tmrecipes.Model.DataHome
因为Home1
节点下的Home1
节点是字符串而不是DataHome
对象。 要解决此问题,您需要向FirebaseRecyclerOptions
对象传递一个查询,该查询指向DataHome
对象所在的节点。 因此,请更改以下代码行:
Query query = FirebaseDatabase.getInstance()
.getReference("DataHome")
.child("Home1");
到
Query query = FirebaseDatabase.getInstance()
.getReference("DataHome");
看,我已经删除了对.child("Home1")
的调用,因为这会产生错误。 此更改将帮助您显示所有DataHome
节点中存在的所有DataHome
对象。
例如,如果您只想显示Home1
的详细信息,则无需使用 Firebase-UI 库,您只需获取所有属性的值并将它们显示在列表中,如我在这篇文章中的回答中所述:
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