Java 订单活动在空点引用上崩溃
我正在制作order food应用程序。在这里,当我单击order Activity应用程序崩溃时,OrderStatus中出现三个错误。下面的java是logcat和OrderStatus Activity。单击图标后需要显示订单状态 Logcat错误Java 订单活动在空点引用上崩溃,java,android,firebase,Java,Android,Firebase,我正在制作order food应用程序。在这里,当我单击order Activity应用程序崩溃时,OrderStatus中出现三个错误。下面的java是logcat和OrderStatus Activity。单击图标后需要显示订单状态 Logcat错误 java.lang.NullPointerException: Attempt to invoke virtual method 'int java.lang.String.hashCode()' on a null object re
java.lang.NullPointerException: Attempt to invoke virtual method 'int java.lang.String.hashCode()' on a null object reference
at com.example.sharma.digimenuserver.Common.Common.convertCodeToStatus(Common.java:16)
at com.example.sharma.digimenuserver.OrderStatus$1.onBindViewHolder(OrderStatus.java:78)
at com.example.sharma.digimenuserver.OrderStatus$1.onBindViewHolder(OrderStatus.java:64)
at com.firebase.ui.database.FirebaseRecyclerAdapter.onBindViewHolder(FirebaseRecyclerAdapter.java:122)
at android.support.v7.widget.RecyclerView$Adapter.onBindViewHolder(RecyclerView.java:6673)
at android.support.v7.widget.RecyclerView$Adapter.bindViewHolder(RecyclerView.java:6714)
at android.support.v7.widget.RecyclerView$Recycler.tryBindViewHolderByDeadline(RecyclerView.java:5647)
at android.support.v7.widget.RecyclerView$Recycler.tryGetViewHolderForPositionByDeadline(RecyclerView.java:5913)
at android.support.v7.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:5752)
at android.support.v7.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:5748)
at android.support.v7.widget.LinearLayoutManager$LayoutState.next(LinearLayoutManager.java:2232)
at android.support.v7.widget.LinearLayoutManager.layoutChunk(LinearLayoutManager.java:1559)
at android.support.v7.widget.LinearLayoutManager.fill(LinearLayoutManager.java:1519)
at android.support.v7.widget.LinearLayoutManager.onLayoutChildren(LinearLayoutManager.java:614)
at android.support.v7.widget.RecyclerView.dispatchLayoutStep2(RecyclerView.java:3812)
at android.support.v7.widget.RecyclerView.dispatchLayout(RecyclerView.java:3529)
at android.support.v7.widget.RecyclerView.consumePendingUpdateOperations(RecyclerView.java:1767)
at android.support.v7.widget.RecyclerView$1.run(RecyclerView.java:356)
at android.view.Choreographer$CallbackRecord.run(Choreographer.java:767)
at android.view.Choreographer.doCallbacks(Choreographer.java:580)
at android.view.Choreographer.doFrame(Choreographer.java:549)
at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:753)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5292)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:904)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:699)
07-22 17:30:08.181 3099-3109/com.example.sharma.digimenuserver I/art: Debugger is no longer active
07-22 17:34:22.748 3099-3141/com.example.sharma.digimenuserver I/FirebaseAuth: [FirebaseAuth:] Loading module via
OrderStatus.java
公共类OrderStatus扩展了AppCompatActivity{
RecyclerView recyclerView;
RecyclerView.LayoutManager layoutManager;
FirebaseRecyclerAdapter<Request,OrderViewHolder> adapter;
FirebaseDatabase db;
DatabaseReference requests;
MaterialSpinner spinnner;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_order_status);
db = FirebaseDatabase.getInstance();
requests=db.getReference("Requests");
recyclerView = (RecyclerView)findViewById(R.id.listOrders);
recyclerView.setHasFixedSize(true);
layoutManager = new LinearLayoutManager(this);
recyclerView.setLayoutManager(layoutManager);
loadOrders();
}
private void loadOrders() {
FirebaseRecyclerOptions<Request> options =
new FirebaseRecyclerOptions.Builder<Request>()
.setQuery(requests, Request.class).build();
adapter = new FirebaseRecyclerAdapter<Request, OrderViewHolder>(options) {
@NonNull
@Override
public OrderViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext())
.inflate(R.layout.order_layout, parent, false);
return new OrderViewHolder(view);
}
@Override
protected void onBindViewHolder(@NonNull OrderViewHolder holder, int position, @NonNull Request model) {
//do binding stuff
holder.txtOrderId.setText(adapter.getRef(position).getKey());
holder.txtOrderStatus.setText(Common.convertCodeToStatus(model.getStatus()));
holder.txtOrderAddress.setText(model.getAddress());
holder.txtOrderPhone.setText(model.getPhone());
holder.setItemClickListener(new ItemClickListener() {
@Override
public void onClick(View view, int position, boolean isLongClick) {
}
});
}
};
adapter.notifyDataSetChanged();
recyclerView.setAdapter(adapter);
adapter.startListening();
}
@Override
public boolean onContextItemSelected(MenuItem item) {
if(item.getTitle().equals(Common.UPDATE))
showUpdateDialog(adapter.getRef(item.getOrder()).getKey(),adapter.getItem(item.getOrder()));
else if(item.getTitle().equals(Common.DELETE))
deleteOrder(adapter.getRef(item.getOrder()).getKey());
return super.onContextItemSelected(item);
}
private void deleteOrder(String key) {
requests.child(key).removeValue();
}
private void showUpdateDialog(String key, final Request item) {
final AlertDialog.Builder alertDialog = new AlertDialog.Builder(OrderStatus.this);
alertDialog.setTitle("Update Order");
alertDialog.setMessage("Please Choose Status");
LayoutInflater inflater = this.getLayoutInflater();
final View view = inflater.inflate(R.layout.update_order_layout,null);
spinnner = (MaterialSpinner)findViewById(R.id.statusSpinner);
spinnner.setItems("Placed","On my way","Shipped");
alertDialog.setView(view);
final String localKey = key;
alertDialog.setPositiveButton("YES", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
dialog.dismiss();
item.setStatus(String.valueOf(spinnner.getSelectedIndex()));
requests.child(localKey).setValue(item);
}
});
alertDialog.setNegativeButton("NO", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
dialog.dismiss();
}
});
alertDialog.show();
}
RecyclerView-RecyclerView;
RecyclerView.LayoutManager LayoutManager;
FirebaseRecyclerAdapter适配器;
FirebaseDB数据库;
数据库参考请求;
材料纺纱机;
@凌驾
创建时受保护的void(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.activity\u order\u status);
db=FirebaseDatabase.getInstance();
请求=db.getReference(“请求”);
recyclerView=(recyclerView)findViewById(R.id.listOrders);
recyclerView.setHasFixedSize(true);
layoutManager=新的LinearLayoutManager(此);
recyclerView.setLayoutManager(layoutManager);
loadOrders();
}
私人作废订单(){
FirebaseRecyclerOptions选项=
新的FirebaseRecyclerOptions.Builder()
.setQuery(requests,Request.class).build();
适配器=新的FirebaseRecyclerAdapter(选项){
@非空
@凌驾
public OrderViewHolder onCreateViewHolder(@NonNull ViewGroup父级,int-viewType){
View=LayoutInflater.from(parent.getContext())
.充气(R.layout.order_layout,父级,false);
返回新的OrderViewHolder(视图);
}
@凌驾
受保护的无效onBindViewHolder(@NonNull OrderViewHolder,int位置,@NonNull请求模型){
//装订
holder.txtOrderId.setText(adapter.getRef(position.getKey());
holder.txtOrderStatus.setText(Common.convertCodeToStatus(model.getStatus());
holder.txtOrderAddress.setText(model.getAddress());
holder.txtordphone.setText(model.getPhone());
setItemClickListener(新的ItemClickListener(){
@凌驾
公共void onClick(视图、int位置、布尔值isLongClick){
}
});
}
};
adapter.notifyDataSetChanged();
recyclerView.setAdapter(适配器);
adapter.startListening();
}
@凌驾
公共布尔值onContextItemSelected(MenuItem项){
if(item.getTitle().equals(Common.UPDATE))
showUpdateDialog(adapter.getRef(item.getOrder()).getKey()、adapter.getItem(item.getOrder());
else if(item.getTitle().equals(Common.DELETE))
deleteOrder(adapter.getRef(item.getOrder()).getKey());
返回super.onContextItemSelected(项目);
}
私有void deleteOrder(字符串键){
requests.child(key.removeValue();
}
私有void showUpdateDialog(字符串键,最终请求项){
final AlertDialog.Builder AlertDialog=新建AlertDialog.Builder(OrderStatus.this);
alertDialog.setTitle(“更新顺序”);
alertDialog.setMessage(“请选择状态”);
LayoutInflater充气机=this.getLayoutInflater();
最终视图=充气机。充气(R.layout.update\u order\u layout,null);
Spinner=(MaterialSpinner)findViewById(R.id.statusSpinner);
spinnner.setItems(“已放置”、“正在途中”、“已装运”);
alertDialog.setView(视图);
最后一个字符串localKey=key;
alertDialog.setPositiveButton(“是”,新的DialogInterface.OnClickListener(){
@凌驾
public void onClick(DialogInterface dialog,int which){
dialog.dismise();
item.setStatus(String.valueOf(spinner.getSelectedIndex());
requests.child(localKey).setValue(item);
}
});
alertDialog.setNegativeButton(“否”,新的DialogInterface.OnClickListener(){
@凌驾
public void onClick(DialogInterface dialog,int which){
dialog.dismise();
}
});
alertDialog.show();
}
}
**在三行中获取错误**
switch (code) {
case "0":
return "Placed";
case "1":
return "On my way";
default:
return "Shipped";
}
holder.txtOrderStatus.setText(Common.convertCodeToStatus(model.getStatus()));
adapter = new FirebaseRecyclerAdapter<Request, OrderViewHolder>(options) {
https://send.firefox.com/download/80a23ccfae/#W_ricyMLLaYtPkPg_UGNFA
开关(代码){
案例“0”:
返回“放置”;
案例“1”:
返回“在我的路上”;
违约:
返回“已装运”;
}
holder.txtOrderStatus.setText(Common.convertCodeToStatus(model.getStatus());
适配器=新的FirebaseRecyclerAdapter(选项){
https://send.firefox.com/download/80a23ccfae/#W_ricyMLLaYtPkPg_UGNFA
您没有提到哪一行,但我最好的猜测是code
为空,可能需要检查一下。
Java同时使用
.equals()
和.hashCode()
来验证switch语句中的字符串,所以如果代码为null,您将得到此错误您没有提到哪一行,但我的最佳猜测是代码
为null可能需要检查一下。
Java同时使用
.equals()
和.hashCode()
来验证switch语句中的字符串,因此如果代码为null,则会出现此错误错误发生在“convertCodeToStatus()”过程中,因此我认为您的“model.getStatus()”正在返回null。错误发生在“convertCodeToStatus()中”过程,所以我认为您的“model.getStatus()”正在返回NULL。在开关的第一行和下面的两行上,我得到了错误正如我告诉您检查code
是否为NULL,java同时使用.equals()
和.hash()
验证switch语句中的字符串,因此,如果code
为null,您将在switch case的第一行和下面两行得到此错误,正如我告诉您的,检查code
是否为null,java同时使用.equals()
和.hash()
验证switch语句中的字符串,因此如果code
为null,则会出现此错误。问题发生在Common.java
的第16行,您没有共享该行。正如其他人所回答的,您在null
的对象上调用了hashCode
。请参阅q