您好我已经阅读了所有类似的问题/答案，我想我可以肯定这与选定的主题无关！
我现在使用主题灯，因此操作栏nullpointer问题应该没有问题。
这里有例外：
05-21 09:54:47.076: E/AndroidRuntime(24459): FATAL EXCEPTION: main
05-21 09:54:47.076: E/AndroidRuntime(24459): Process: de.poetjan.powerconsumption, PID: 24459
05-21 09:54:47.076: E/AndroidRuntime(24459): java.lang.NullPointerException
05-21 09:54:47.076: E/AndroidRuntime(24459): at de.poetjan.powerconsumption.Verbrauch.onCreateView(Verbrauch.java:131)
05-21 09:54:47.076: E/AndroidRuntime(24459): at android.support.v4.app.Fragment.performCreateView(Fragment.java:1500)
05-21 09:54:47.076: E/AndroidRuntime(24459): at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:927)
05-21 09:54:47.076: E/AndroidRuntime(24459): at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1104)
05-21 09:54:47.076: E/AndroidRuntime(24459): at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:682)
05-21 09:54:47.076: E/AndroidRuntime(24459): at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1467)
05-21 09:54:47.076: E/AndroidRuntime(24459): at android.support.v4.app.FragmentManagerImpl.executePendingTransactions(FragmentManager.java:472)
05-21 09:54:47.076: E/AndroidRuntime(24459): at android.support.v4.app.FragmentPagerAdapter.finishUpdate(FragmentPagerAdapter.java:141)
05-21 09:54:47.076: E/AndroidRuntime(24459): at android.support.v4.view.ViewPager.populate(ViewPager.java:1068)
05-21 09:54:47.076: E/AndroidRuntime(24459): at android.support.v4.view.ViewPager.populate(ViewPager.java:914)
05-21 09:54:47.076: E/AndroidRuntime(24459): at android.support.v4.view.ViewPager.onMeasure(ViewPager.java:1436)
这里是我的片段Verbrauch.java;
package de.poetjan.powerconsumption;
import java.text.DecimalFormat;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
import android.app.AlertDialog;
import android.app.DatePickerDialog.OnDateSetListener;
import android.content.DialogInterface;
import android.net.ParseException;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentActivity;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.DatePicker;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;
import android.widget.ToggleButton;
public class Verbrauch extends Fragment {
private double ba;
private double ea;
private double zwischen;
// private AdView adView;
int mYear1;
int mMonth1;
int mDay1;
int mYear2;
int mMonth2;
int mDay2;
Button pickdate;
Button pickdate2;
Button berechnen;
ToggleButton month;
ToggleButton quarteryear;
ToggleButton halfyear;
ToggleButton year;
EditText dateDisplay1;
EditText dateDisplay2;
EditText kwhDisplay1;
EditText kwhDisplay2;
TextView textView5;
TextView textView6;
TextView textView50;
EditText editText5;
long diff;
int differ;
String fromDate;
String toDate;
String neuformatjahr1;
String neuformatmonat1;
String neuformattag1;
String neuformatjahr2;
String neuformatmonat2;
String neuformattag2;
String gesamt2o;
String gesamt1o;
private boolean mBool = false;
private boolean firststart = false;
final SimpleDateFormat df = new SimpleDateFormat("ddMMyyyy");
final DecimalFormat formatter = new DecimalFormat("#.##");
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.verbrauch, container, false);
getActivity();
//initialize ViewElements
boolean firstboot = getActivity().getSharedPreferences("BOOT_PREF", FragmentActivity.MODE_PRIVATE).getBoolean("firstboot", true);
dateDisplay1 = (EditText) rootView.findViewById(R.id.dateDisplay1);
dateDisplay2 = (EditText) rootView.findViewById(R.id.dateDisplay2);
kwhDisplay1 = (EditText) rootView.findViewById(R.id.kwhDisplay1);
kwhDisplay2 = (EditText) rootView.findViewById(R.id.kwhDisplay2);
editText5 = (EditText) rootView.findViewById(R.id.editText5);
textView5 = (TextView) rootView.findViewById(R.id.textView5);
textView6 = (TextView) rootView.findViewById(R.id.textView6);
textView50 = (TextView) rootView.findViewById(R.id.textView50);
pickdate = (Button) rootView.findViewById(R.id.pickDate);
pickdate2 = (Button) rootView.findViewById(R.id.pickDate2);
berechnen = (Button) rootView.findViewById(R.id.button10);
month = (ToggleButton) rootView.findViewById(R.id.button1);
quarteryear = (ToggleButton) rootView.findViewById(R.id.button2);
halfyear = (ToggleButton) rootView.findViewById(R.id.button3);
year = (ToggleButton) rootView.findViewById(R.id.button4);
// Bei erstem Start Anleitung zeigen
if (firstboot){
// 1) Launch the authentication activity
getActivity();
// 2) Then save the state
getActivity().getSharedPreferences("BOOT_PREF", FragmentActivity.MODE_PRIVATE)
.edit()
.putBoolean("firstboot", false)
.commit();
AlertDialog.Builder alertbox = new AlertDialog.Builder(getActivity());
alertbox.setMessage(R.string.firststart);
alertbox.setNeutralButton("Ok", new DialogInterface.OnClickListener() {
// click listener on the alert box
public void onClick(DialogInterface arg0, int arg1) {
// the button was clicked
}
});
// show it
alertbox.show();
}
// Button SET 1
pickdate.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
showDatePicker1();
}}
);
// Button Abschlag berechnen
berechnen.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
try {
if(textView5.getText().toString().isEmpty() || editText5.getText().toString().isEmpty()) {
Toast.makeText(getActivity(), R.string.beideeingebenab, Toast.LENGTH_SHORT).show();
}
else {
if (firststart == true) {
Double verbrauchsmenge = Double.valueOf(textView5.getText().toString().replace(',', '.'));
Double preisprok = Double.parseDouble(editText5.getText().toString().replace(',', '.'));
Double ERG = verbrauchsmenge * preisprok;
textView50.setText(formatter.format(ERG));
}
else {
Toast.makeText(getActivity(), R.string.calfirst, Toast.LENGTH_SHORT).show();
}
}
}
catch (NumberFormatException e) {}
}}
);
// Button SET 2
pickdate2.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if(dateDisplay1.getText().toString().matches("")) {
Toast.makeText(getActivity(), R.string.zuersteingeben, Toast.LENGTH_SHORT).show();
}
else {
showDatePicker2();
}
}}
);
// Button Month
month.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
try {
Double a = Double.parseDouble(kwhDisplay1.getText().toString());
Double b = Double.parseDouble(kwhDisplay2.getText().toString());
if (a < b) {
getdaysbetween();
berechnemonat();
mBool = true;
month.setChecked(mBool);
mBool = false;
quarteryear.setChecked(mBool);
halfyear.setChecked(mBool);
year.setChecked(mBool);
}
else {
Toast.makeText(getActivity(), R.string.musskleinersein, Toast.LENGTH_SHORT).show();
mBool = true;
month.setChecked(mBool);
mBool = false;
quarteryear.setChecked(mBool);
halfyear.setChecked(mBool);
year.setChecked(mBool);
}
}
catch (NumberFormatException e) {
Toast.makeText(getActivity(), R.string.beideeingeben, Toast.LENGTH_SHORT).show();
mBool = true;
month.setChecked(mBool);
mBool = false;
quarteryear.setChecked(mBool);
halfyear.setChecked(mBool);
year.setChecked(mBool);
}
}}
);
//Button Vierteljahr
quarteryear.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
try {
Double a = Double.parseDouble(kwhDisplay1.getText().toString());
Double b = Double.parseDouble(kwhDisplay2.getText().toString());
if (a < b) {
getdaysbetween();
berechnequarter();
mBool = true;
quarteryear.setChecked(mBool);
mBool = false;
month.setChecked(mBool);
halfyear.setChecked(mBool);
year.setChecked(mBool);
}
else {
Toast.makeText(getActivity(), R.string.musskleinersein, Toast.LENGTH_SHORT).show();
mBool = true;
quarteryear.setChecked(mBool);
mBool = false;
month.setChecked(mBool);
halfyear.setChecked(mBool);
year.setChecked(mBool);
}
}
catch (NumberFormatException e) {
Toast.makeText(getActivity(), R.string.beideeingeben, Toast.LENGTH_SHORT).show();
mBool = true;
quarteryear.setChecked(mBool);
mBool = false;
month.setChecked(mBool);
halfyear.setChecked(mBool);
year.setChecked(mBool);
}
}}
);
//Button Halbjahr
halfyear.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
try {
Double a = Double.parseDouble(kwhDisplay1.getText().toString());
Double b = Double.parseDouble(kwhDisplay2.getText().toString());
if (a < b) {
getdaysbetween();
berechnehalf();
mBool = true;
halfyear.setChecked(mBool);
mBool = false;
quarteryear.setChecked(mBool);
month.setChecked(mBool);
year.setChecked(mBool);
}
else {
Toast.makeText(getActivity(), R.string.musskleinersein, Toast.LENGTH_SHORT).show();
mBool = true;
halfyear.setChecked(mBool);
mBool = false;
quarteryear.setChecked(mBool);
month.setChecked(mBool);
year.setChecked(mBool);
}
}
catch (NumberFormatException e) {
Toast.makeText(getActivity(), R.string.beideeingeben, Toast.LENGTH_SHORT).show();
mBool = true;
halfyear.setChecked(mBool);
mBool = false;
quarteryear.setChecked(mBool);
month.setChecked(mBool);
year.setChecked(mBool);
}
}}
);
//Button Jahr
year.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
try {
Double a = Double.parseDouble(kwhDisplay1.getText().toString());
Double b = Double.parseDouble(kwhDisplay2.getText().toString());
if (a < b) {
getdaysbetween();
berechneyear();
mBool = true;
year.setChecked(mBool);
mBool = false;
quarteryear.setChecked(mBool);
halfyear.setChecked(mBool);
month.setChecked(mBool);
}
else {
Toast.makeText(getActivity(), R.string.musskleinersein, Toast.LENGTH_SHORT).show();
mBool = true;
year.setChecked(mBool);
mBool = false;
quarteryear.setChecked(mBool);
halfyear.setChecked(mBool);
month.setChecked(mBool);
}
}
catch (NumberFormatException e) {
Toast.makeText(getActivity(), R.string.beideeingeben, Toast.LENGTH_SHORT).show();
mBool = true;
year.setChecked(mBool);
mBool = false;
quarteryear.setChecked(mBool);
halfyear.setChecked(mBool);
month.setChecked(mBool);
}
}}
);
return rootView;
}
// Methode zur Berechnung der kWh-Differenz im Zeitraum für Monat
private void berechnemonat(){
if (kwhDisplay1.getText().toString().isEmpty() || kwhDisplay2.getText().toString().isEmpty()) {
Toast.makeText(getActivity(), R.string.beideeingeben, Toast.LENGTH_SHORT).show();
}
else if (dateDisplay1.getText().toString().isEmpty() || dateDisplay2.getText().toString().isEmpty()){
Toast.makeText(getActivity(), R.string.hintdateset, Toast.LENGTH_SHORT).show();
}
else {
ba = Double.valueOf(kwhDisplay1.getText().toString());
ea = Double.valueOf(kwhDisplay2.getText().toString());
zwischen = ((ea-ba)/differ)*30.41666666666667;
textView5.setText(String.valueOf(formatter.format(zwischen)));
}
}
//Methode zur Berechnung der kWh-Differenz im Zeitraum für vierteljahr
private void berechnequarter(){
if (kwhDisplay1.getText().toString().isEmpty() || kwhDisplay2.getText().toString().isEmpty()) {
Toast.makeText(getActivity(), R.string.beideeingeben, Toast.LENGTH_SHORT).show();
}
else if (dateDisplay1.getText().toString().isEmpty() || dateDisplay2.getText().toString().isEmpty()){
Toast.makeText(getActivity(), R.string.hintdateset, Toast.LENGTH_SHORT).show();
}
else {
ba = Double.valueOf(kwhDisplay1.getText().toString());
ea = Double.valueOf(kwhDisplay2.getText().toString());
zwischen = ((ea-ba)/differ)*91.25;
textView5.setText(String.valueOf(formatter.format(zwischen)));
}
}
//Methode zur Berechnung der kWh-Differenz im Zeitraum für Halbjahr
private void berechnehalf(){
if (kwhDisplay1.getText().toString().isEmpty() || kwhDisplay2.getText().toString().isEmpty()) {
Toast.makeText(getActivity(), R.string.beideeingeben, Toast.LENGTH_SHORT).show();
}
else if (dateDisplay1.getText().toString().isEmpty() || dateDisplay2.getText().toString().isEmpty()){
Toast.makeText(getActivity(), R.string.hintdateset, Toast.LENGTH_SHORT).show();
}
else {
ba = Double.valueOf(kwhDisplay1.getText().toString());
ea = Double.valueOf(kwhDisplay2.getText().toString());
zwischen = ((ea-ba)/differ)*182.5;
textView5.setText(String.valueOf(formatter.format(zwischen)));
}
}
//Methode zur Berechnung der kWh-Differenz im Zeitraum für Jahr
private void berechneyear(){
if (kwhDisplay1.getText().toString().isEmpty() || kwhDisplay2.getText().toString().isEmpty()) {
Toast.makeText(getActivity(), R.string.beideeingeben, Toast.LENGTH_SHORT).show();
}
else if (dateDisplay1.getText().toString().isEmpty() || dateDisplay2.getText().toString().isEmpty()){
Toast.makeText(getActivity(), R.string.hintdateset, Toast.LENGTH_SHORT).show();
}
else {
ba = Double.valueOf(kwhDisplay1.getText().toString());
ea = Double.valueOf(kwhDisplay2.getText().toString());
zwischen = ((ea-ba)/differ)*365;
textView5.setText(String.valueOf(formatter.format(zwischen)));
}
}
// Methode zur Berechnung der Anzahl der Tage im Zeitraum
private void getdaysbetween(){
if(dateDisplay1.getText().toString().isEmpty() || dateDisplay2.getText().toString().isEmpty()) {
Toast.makeText(getActivity(), R.string.beideeingeben, Toast.LENGTH_SHORT).show();
}
else {
try {
fromDate = gesamt1o;
toDate = gesamt2o;
firststart = true;
try {
//Convert to Date
Date startDate = df.parse(gesamt1o);
Calendar c1 = Calendar.getInstance();
//Change to Calendar Date
c1.setTime(startDate);
//Convert to Date
Date endDate = df.parse(gesamt2o);
Calendar c2 = Calendar.getInstance();
//Change to Calendar Date
c2.setTime(endDate);
//get Time in milli seconds
long ms1 = c1.getTimeInMillis();
long ms2 = c2.getTimeInMillis();
//get difference in milli seconds
diff = ms2 - ms1;
} catch (ParseException e) {
e.printStackTrace();
} catch (java.text.ParseException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
//Find number of days by dividing the mili seconds
int diffInDays = (int) (diff / (24 * 60 * 60 * 1000));
differ = diffInDays;
}
catch (NumberFormatException e) {
Toast.makeText(getActivity(), getActivity().getResources().getString(R.string.err), Toast.LENGTH_SHORT).show();
}
}
}
// Zeige DatePickerFragment1
private void showDatePicker1() {
DatePickerFragment date = new DatePickerFragment();
/**
* Set Up Current Date Into dialog
*/
Calendar calender = Calendar.getInstance();
Bundle args = new Bundle();
args.putInt("year", calender.get(Calendar.YEAR));
args.putInt("month", calender.get(Calendar.MONTH));
args.putInt("day", calender.get(Calendar.DAY_OF_MONTH));
date.setArguments(args);
/**
// * Set Call back to capture selected date
// */
date.setCallBack(ondate);
date.show(getChildFragmentManager(), "Date Picker");
}
OnDateSetListener ondate = new OnDateSetListener() {
@Override
public void onDateSet(DatePicker view, int year, int monthOfYear,
int dayOfMonth) {
mYear1 = year;
mMonth1 = monthOfYear;
mDay1 = dayOfMonth;
neuformatjahr1 = String.valueOf(mYear1);
if (mMonth1+1 < 10){
neuformatmonat1 = "0"+ String.valueOf(mMonth1+1);
}
else {neuformatmonat1 = String.valueOf(mMonth1+1);}
if (mDay1 < 10){
neuformattag1 = "0"+ String.valueOf(mDay1);
}
else {neuformattag1 =String.valueOf(mDay1);}
gesamt1o = neuformattag1+neuformatmonat1+neuformatjahr1;
String gesamt1 = neuformattag1+"."+neuformatmonat1+"."+neuformatjahr1;
dateDisplay1.setText(gesamt1);
}
};
//Zeige DatePickerFragment2
private void showDatePicker2() {
DatePickerFragment date = new DatePickerFragment();
/**
* Set Up Current Date Into dialog
*/
Calendar calender = Calendar.getInstance();
Bundle args = new Bundle();
args.putInt("year", calender.get(Calendar.YEAR));
args.putInt("month", calender.get(Calendar.MONTH));
args.putInt("day", calender.get(Calendar.DAY_OF_MONTH));
date.setArguments(args);
/**
* Set Call back to capture selected date
*/
date.setCallBack(ondate2);
date.show(getChildFragmentManager(), "Date Picker");
}
OnDateSetListener ondate2 = new OnDateSetListener() {
@Override
public void onDateSet(DatePicker view, int year, int monthOfYear,
int dayOfMonth) {
mYear2 = year;
mMonth2 = monthOfYear;
mDay2 = dayOfMonth;
neuformatjahr2 = String.valueOf(mYear2);
if (mMonth2+1 < 10){
neuformatmonat2 = "0"+ String.valueOf(mMonth2+1);
}
else {neuformatmonat2 = String.valueOf(mMonth2+1);}
if (mDay2 < 10){
neuformattag2 = "0"+ String.valueOf(mDay2);
}
else{neuformattag2 =String.valueOf(mDay2);}
gesamt2o = neuformattag2+neuformatmonat2+neuformatjahr2;
String gesamt2 = neuformattag2+"."+neuformatmonat2+"."+neuformatjahr2;
dateDisplay2.setText(gesamt2);
}
};
}
答案 0 :(得分：2)
我认为你的按钮 berechnen 为空。当您设置onClickListener时，在此之前放置一个空检查。并且您无法从XML文件中获取此参考。
答案 1 :(得分：0)
您可能需要添加onCreate()方法，尝试添加：
protected void onCreate (Bundle savedInstanceState)
{
super.onCreate (savedInstanceState);
setContentView (R.layout.name_of_your_fragment_xml);
//add fragment
.....
}
答案 2 :(得分：0)
您正在尝试访问片段的onCreateView中的活动，该活动主要导致NPE，尝试将getActivity（）内容移动到
onActivityCreated(Bundle savedInstanceState)
阅读有关片段生命周期和活动生命周期的更多信息