[英]'java.lang.String android.content.Context.getPackageName()' on a null object reference error
[英]DialogFragment 'java.lang.String android.content.Context.getPackageName()' on a null object reference
我正在使用DialogFragment並使用Volley將數據插入mysql。 數據已成功插入數據庫,但之后始終會崩潰。 我總是在我的logcat java.lang.NullPointerException中收到此錯誤:嘗試在空對象引用上調用虛擬方法'java.lang.String android.content.Context.getPackageName()'。錯誤在我的Toast中。 請幫忙
public class ExpensesLeisureDialog extends DialogFragment {
EditText name, amount, details;
String nameHolder, amountHolder, detailsHolder;
Boolean CheckEditText;
RequestQueue requestQueue;
HashMap<String,String> hashMap = new HashMap<>();
String finalResult;
HttpParse httpParse = new HttpParse();
String HttpURL = "http://10.0.2.2:63343/TheMoneyger/api/add-leisure.php";
@Override
public Dialog onCreateDialog (Bundle savedInstanceState) {
AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());
LayoutInflater inflater = getActivity().getLayoutInflater();
builder.setView(inflater.inflate(R.layout.fragment_add_expenses_dialog, null));
requestQueue = Volley.newRequestQueue(getActivity().getApplicationContext());
builder.setTitle("Add leisure expense")
.setPositiveButton("Add", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
name = (EditText) getDialog().findViewById(R.id.editText1);
amount = (EditText) getDialog().findViewById(R.id.editText2);
details = (EditText) getDialog().findViewById(R.id.editText3);
CheckEditTextIsEmpty();
StringRequest stringRequest = new StringRequest(Request.Method.POST, HttpURL,
new Response.Listener<String>() {
@Override
public void onResponse(String response) {
Toast.makeText(getContext(), response, Toast.LENGTH_SHORT).show();
}
},
new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
Toast.makeText(getContext(), error.toString(), Toast.LENGTH_SHORT).show();
}
}) {
@Override
protected Map<String, String> getParams() {
Map<String, String> params = new HashMap<String, String>();
params.put("expensename", nameHolder);
params.put("expenseamount", amountHolder);
params.put("details", detailsHolder);
return params;
}
};
RequestQueue requestQueue = Volley.newRequestQueue(getActivity());
requestQueue.add(stringRequest);
}
})
.setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
dialog.dismiss();
}
});
return builder.create();
}
public void CheckEditTextIsEmpty() {
nameHolder = name.getText().toString();
amountHolder = amount.getText().toString();
detailsHolder = details.getText().toString();
}
這是我的日志
java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String android.content.Context.getPackageName()' on a null object reference
at android.widget.Toast.<init>(Toast.java:114)
at android.widget.Toast.makeText(Toast.java:277)
at android.widget.Toast.makeText(Toast.java:267)
at com.example.merylle.themoneyger.fragment.ExpensesLeisureDialog$2$1.onResponse(ExpensesLeisureDialog.java:65)
at com.example.merylle.themoneyger.fragment.ExpensesLeisureDialog$2$1.onResponse(ExpensesLeisureDialog.java:62)
at com.android.volley.toolbox.StringRequest.deliverResponse(StringRequest.java:60)
at com.android.volley.toolbox.StringRequest.deliverResponse(StringRequest.java:30)
at com.android.volley.ExecutorDelivery$ResponseDeliveryRunnable.run(ExecutorDelivery.java:99)
at android.os.Handler.handleCallback(Handler.java:790)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:164)
at android.app.ActivityThread.main(ActivityThread.java:6494)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:807)
嘗試這個
getContext:-它是應用程序/對象當前狀態的上下文。
Toast.makeText(getContext(), response, Toast.LENGTH_SHORT).show();
將getContext更改為getActivity,如下所示:
Toast.makeText(getActivity(), response, Toast.LENGTH_SHORT).show();
getActivity: -getActivity是一個函數,它返回一個Activity。 它是Fragment的功能,並返回該片段所附加的Activity。 如果片段沒有任何活動,則為null。
希望對您有幫助
更新
調用onAttach方法時存儲上下文 。
public class ExpensesLeisureDialog extends DialogFragment {
Context context;
@Override
public void onAttach(Context context) {
super.onAttach(context);
this.context = context;
}
.
.
}
並在需要時使用上下文變量。
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