嗯,我喜欢解析来自适配器片段串,我怎么能做到这一点?因为我得到了我的应用空间字符串。
这从我的适配器代码
适配器
public class listAdapter extends RecyclerView.Adapter<listAdapter.ViewHolder> {
private Simpleway simpleway = new Simpleway();
private ArrayList<DataFirebase> dataList;
private AppCompatActivity someActivity;
private TitleFragment fragmentTitle = new TitleFragment();
private ModelData model = new ModelData();
public listAdapter(ArrayList<DataFirebase> dataList, AppCompatActivity someActivity) {
this.dataList = dataList;
this.someActivity = someActivity;
}
@NonNull
@Override
public ViewHolder onCreateViewHolder(@NonNull ViewGroup viewGroup, int i) {
View view = LayoutInflater.from(viewGroup.getContext())
.inflate(R.layout.item_label, viewGroup, false);
return new ViewHolder(view);
}
@Override
public void onBindViewHolder(@NonNull final ViewHolder viewHolder, int positions) {
final DataFirebase labelList = dataList.get(positions);
viewHolder.textLabel.setText(labelList.getLabel());
viewHolder.itemView.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
String enough = labelList.getLabel();
model.setLabel(enough);
simpleway.toastMessage(someActivity, model.getLabel());
someActivity.getSupportFragmentManager()
.beginTransaction()
.setCustomAnimations(R.anim.enter_from_right, R.anim.exit_to_right, R.anim.enter_from_right, R.anim.exit_to_right)
.replace(R.id.container_layout, fragmentTitle)
.addToBackStack(null)
.commit();
}
});
}
@Override
public int getItemCount() {
return dataList.size();
}
public class ViewHolder extends RecyclerView.ViewHolder {
public LinearLayout linearLabel;
public TextView textLabel;
public ViewHolder(@NonNull View itemView) {
super(itemView);
textLabel = itemView.findViewById(R.id.text_label);
linearLabel = itemView.findViewById(R.id.linearLabel);
}
}
}
所以多半我的适配器将打开我的标题片段和使用POJO,但经过串代码,我没有得到我的POJO任何数据字符串所以在这里看我的标题类片段
TitleFragment
public class TitleFragment extends BaseFragment {
private DatabaseReference databaseReference;
private RecyclerView titleRecycleView;
private ArrayList<DataFirebase> listLabel;
private com.example.parzival.flashcard.adapter.titleAdapter titleAdapter;
private DataFirebase dataFirebase = new DataFirebase();
private ModelData modelData = new ModelData();
@Override
public void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
@Nullable
@Override
public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_title, container, false);
findView(view);
check();
// setDataToList(view);
initListener(view);
putLayoutManager(view);
return view;
}
private void check() {
if (modelData.getLabel().equals("")) {
simpleway.toastMessage(getContext(), "null");
} else {
simpleway.toastMessage(getContext(), modelData.getLabel());
}
}
private void setDataToList(View view) {
databaseReference.child(modelData.getLabel()).addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
listLabel = new ArrayList<>();
for (DataSnapshot dataSnap : dataSnapshot.getChildren()) {
DataFirebase dataText = dataSnap.getValue(DataFirebase.class);
dataText.setTitle(dataSnap.getKey());
listLabel.add(dataText);
}
titleAdapter = new titleAdapter(listLabel, TitleFragment.this);
titleRecycleView.setAdapter(titleAdapter);
}
@Override
public void onCancelled(@NonNull DatabaseError databaseError) {
System.out.print(databaseError.getDetails() + "" + databaseError.getMessage());
}
});
}
private void putLayoutManager(View view) {
RecyclerView.LayoutManager layoutManager = new LinearLayoutManager(getContext());
titleRecycleView.setLayoutManager(layoutManager);
titleRecycleView.setItemAnimator(new DefaultItemAnimator());
}
@Override
public void findView(View view) {
databaseReference = FirebaseDatabase.getInstance().getReference();
titleRecycleView = view.findViewById(R.id.titleRecycleView);
}
@Override
public void initListener(View view) {
}
}
后,我跑我唯一得到了model.getLabel()
如何空对象?我已经输入型号的字符串,是不是?在model.setLabel(enough)
所以为什么我得到这个错误?
编辑
我试着解释一下我的活动可能是。主要的问题是我使用的一个片段来传递数据,我尝试后我的一些Activity类的为好。
ListActivity
public class ListActivity extends BaseActivity{
private DatabaseReference databaseReference;
private RecyclerView labelRecycleView;
private ArrayList<DataFirebase> listLabel;
private listAdapter listAdapter;
private Button bInput;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_list);
findView();
setDataToList();
initListener();
putLayoutManager();
}
private void setDataToList() {
simpleway.progressDialog(ListActivity.this);
databaseReference.child("Username").addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
listLabel = new ArrayList<>();
for (DataSnapshot dataSnap : dataSnapshot.getChildren()) {
DataFirebase modelClass = dataSnap.getValue(DataFirebase.class);
modelClass.setLabel(dataSnap.getKey());
listLabel.add(modelClass);
}
listAdapter = new listAdapter(listLabel, ListActivity.this);
labelRecycleView.setAdapter(listAdapter);
simpleway.stopProgressDialog();
}
@Override
public void onCancelled(@NonNull DatabaseError databaseError) {
System.out.println(databaseError.getDetails() + " " + databaseError.getMessage());
simpleway.stopProgressDialog();
}
});
}
private void putLayoutManager() {
RecyclerView.LayoutManager layoutManager = new LinearLayoutManager(getApplicationContext());
labelRecycleView.setLayoutManager(layoutManager);
labelRecycleView.setItemAnimator(new DefaultItemAnimator());
}
@Override
public void findView() {
databaseReference = FirebaseDatabase.getInstance().getReference();
labelRecycleView = findViewById(R.id.listRecyclerVIew);
bInput = findViewById(R.id.inputData);
}
@Override
public void initListener() {
bInput.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
simpleway.startnextActivity(ListActivity.this, InputActivity.class);
}
});
}
}
我用的是已经通过了ListActivity不是一个片段,这就是为什么someActivity
public interface CallBackListener {
void onCallBack(String data);// pass any parameter in your onCallBack which you want to return
}
内部片段创建匿名对象
CallBackListener listener=new CallBackListener() {
@Override
public void onCallBack(String data) {
// TODO Auto-generated method stub
}
};
从适配器通过收听者的参考和内部的onClick调用onCallBack(数据);
首先创建一个接口
public interface PassBack {
void valueFromAdapter(String value);
}
然后在你的片段像这样实现这一
public class TitleFragment extends BaseFragment implements PassBack{
private DatabaseReference databaseReference;
private RecyclerView titleRecycleView;
private ArrayList<DataFirebase> listLabel;
private com.example.parzival.flashcard.adapter.titleAdapter titleAdapter;
private DataFirebase dataFirebase = new DataFirebase();
private ModelData modelData = new ModelData();
@Override
public void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
@Nullable
@Override
public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_title, container, false);
findView(view);
check();
// setDataToList(view);
initListener(view);
putLayoutManager(view);
return view;
}
private void check() {
if (modelData.getLabel().equals("")) {
simpleway.toastMessage(getContext(), "null");
} else {
simpleway.toastMessage(getContext(), modelData.getLabel());
}
}
private void setDataToList(View view) {
databaseReference.child(modelData.getLabel()).addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
listLabel = new ArrayList<>();
for (DataSnapshot dataSnap : dataSnapshot.getChildren()) {
DataFirebase dataText = dataSnap.getValue(DataFirebase.class);
dataText.setTitle(dataSnap.getKey());
listLabel.add(dataText);
}
titleAdapter = new titleAdapter(listLabel, TitleFragment.this);
titleRecycleView.setAdapter(titleAdapter);
}
@Override
public void onCancelled(@NonNull DatabaseError databaseError) {
System.out.print(databaseError.getDetails() + "" + databaseError.getMessage());
}
});
}
private void putLayoutManager(View view) {
RecyclerView.LayoutManager layoutManager = new LinearLayoutManager(getContext());
titleRecycleView.setLayoutManager(layoutManager);
titleRecycleView.setItemAnimator(new DefaultItemAnimator());
}
@Override
public void findView(View view) {
databaseReference = FirebaseDatabase.getInstance().getReference();
titleRecycleView = view.findViewById(R.id.titleRecycleView);
}
@Override
public void initListener(View view) {
}
@Override
public void valueFromAdapter(String value) {
//here you will get the value
}
}
然后在适配器中使用这样的
public class listAdapter extends RecyclerView.Adapter<listAdapter.ViewHolder> {
private Simpleway simpleway = new Simpleway();
private ArrayList<DataFirebase> dataList;
private AppCompatActivity someActivity;
private TitleFragment fragmentTitle = new TitleFragment();
private ModelData model = new ModelData();
public listAdapter(ArrayList<DataFirebase> dataList, AppCompatActivity someActivity) {
this.dataList = dataList;
this.someActivity = someActivity;
}
@NonNull
@Override
public ViewHolder onCreateViewHolder(@NonNull ViewGroup viewGroup, int i) {
View view = LayoutInflater.from(viewGroup.getContext())
.inflate(R.layout.item_label, viewGroup, false);
return new ViewHolder(view);
}
@Override
public void onBindViewHolder(@NonNull final ViewHolder viewHolder, int positions) {
final DataFirebase labelList = dataList.get(positions);
viewHolder.textLabel.setText(labelList.getLabel());
viewHolder.itemView.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
String enough = labelList.getLabel();
model.setLabel(enough);
simpleway.toastMessage(someActivity, model.getLabel());
someActivity.valueFromAdapter(enough)//this is how you send your value
}
});
}
@Override
public int getItemCount() {
return dataList.size();
}
public class ViewHolder extends RecyclerView.ViewHolder {
public LinearLayout linearLabel;
public TextView textLabel;
public ViewHolder(@NonNull View itemView) {
super(itemView);
textLabel = itemView.findViewById(R.id.text_label);
linearLabel = itemView.findViewById(R.id.linearLabel);
}
}
}
在您的适配器
A.创建界面
public interface Listener {
void callback(String data);
}
B.创建字段
private Listener listener;
在onCreateViewHolder C.初始化监听器
listener = (Listener)viewGroup.getContext()
D.设定值
String enough = labelList.getLabel();
listener.callback(enough) // Set the value here
在你片段
(单程 )
(其他方式 )
解决方案
我已经尝试使用回答问题,并卡住了。我认为它主要用于活动(纠正我,如果我错了)。因此,唯一的办法,我通过使用论证解决这种情况下,
String enough = labelList.getLabel();
TitleFragment titleFragment = new TitleFragment();
FragmentTransaction fragmentTransaction = someActivity
.getSupportFragmentManager()
.beginTransaction();
从那以后,我用包把一个参数
Bundle bundle = new Bundle();
bundle.putString("Check", enough);
titleFragment.setArguments(bundle);
然后我尝试打开我的片段
fragmentTransaction.setCustomAnimations(R.anim.enter_from_right,
R.anim.exit_to_right, R.anim.enter_from_right, R.anim.exit_to_right)
.replace(R.id.container_layout, titleFragment)
.addToBackStack(null)
.commit();
所以我需要使用的标题片段论证我的字符串
private void setDataToList() {
if (getArguments() != null) {
String newText = getArguments().getString("Check");
simpleway.toastMessage(mContext, newText);
} else {
simpleway.toastMessage(mContext, "Failed");
}
}
并对其做