我有标签;如果我从标签“PIZZA”中选择一个复选框，之后，当我进入第三个标签“BIRRE”时，如果我点击“get_answer”按钮，我希望在第一个标签中选中的复选框位于第二个标签中两个“......但是当我点击按钮时我的代码”get_answer“IDE在三个片段中的”for (Planet p : plAdapter.getBox())“行上说”空指针异常“...我还使用了shared preferences来存储复选框，当我点击另一个选项卡，infact复选框存储....但它不起作用...我不知道为什么....
现在我发布我的代码......
感谢每一个人！
ADAPTER：
public abstract class PlanetAdapter extends ArrayAdapter<Planet> implements CompoundButton.OnCheckedChangeListener
{
private List<Planet> planetList = null;
private Context context = null;
ArrayList<Birra> objects;
private HashMap<Integer, Planet> pizzaSelected = new HashMap<>();
public boolean Checked;
public PlanetAdapter(List<Planet> planetList, Context context) {
super(context, R.layout.single_listview_item, planetList);
this.planetList = planetList;
this.context = context;
}
public class PlanetHolder {
public TextView planetName;
public TextView distView;
public TextView valuta;
public CheckBox chkBox;
public EditText edit;
//public String quantità;
public boolean checked;
public TextView id;
}
@Override
public int getCount() {
return planetList.size();
}
@Override
public Planet getItem(int position) {
return planetList.get(position);
}
@Override
public long getItemId(int position) {
return planetList.get(position).getId();
}
@Override
public View getView(final int position, View convertView, ViewGroup parent) {
View row = convertView;
PlanetHolder holder = null;
if (row == null) {
LayoutInflater inflater = ((Activity) context).getLayoutInflater();
row = inflater.inflate(R.layout.single_listview_item, parent, false);
holder = new PlanetHolder();
holder.planetName = (TextView) row.findViewById(R.id.name);
holder.distView = (TextView) row.findViewById(R.id.dist);
holder.valuta = (TextView) row.findViewById(R.id.valuta);
holder.chkBox = (CheckBox) row.findViewById(R.id.chk_box);
holder.edit = (EditText) row.findViewById(R.id.editText);
holder.edit.setVisibility(View.GONE);
holder.edit.setEnabled(false);
// holder.id = (TextView) row.findViewById(R.id.id);
row.setTag(holder);
} else {
holder = (PlanetHolder) row.getTag();
}
final Planet p = planetList.get(position);
holder.planetName.setText(p.getName());
holder.distView.setText("" + p.getDistance());
holder.valuta.setText("" + p.getValuta());
holder.chkBox.setChecked(p.isSelected());
holder.chkBox.setTag(p);
holder.edit.setEnabled(false);
SharedPreferences states = getContext().getSharedPreferences("states", Context.MODE_PRIVATE);
boolean isChecked = states.getBoolean("holder.chkBox" + holder.planetName.getText().toString(), false);
System.out.println(isChecked);
if (isChecked) {
holder.chkBox.setChecked(true);
holder.edit.setVisibility(View.VISIBLE);
holder.edit.setEnabled(true);
SharedPreferences statess = getContext().getSharedPreferences("states", Context.MODE_PRIVATE);
String string = statess.getString("finalHolder.edit" + holder.planetName.getText().toString(), holder.edit.getText().toString().trim());
holder.edit.setText(string);
} else {
holder.chkBox.setChecked(false);
holder.edit.setVisibility(View.GONE);
holder.edit.setEnabled(false);
}
final PlanetHolder finalHolder = holder;
holder.chkBox.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
@Override
public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
if (finalHolder.chkBox.isChecked()) {
finalHolder.edit.setVisibility(View.VISIBLE);
finalHolder.edit.setEnabled(true);
SharedPreferences states = getContext().getSharedPreferences("states", Context.MODE_PRIVATE);
SharedPreferences.Editor editor = states.edit();
editor.putBoolean("holder.chkBox" + finalHolder.planetName.getText().toString(), true);
editor.commit();
//Utility.putPizzaItem(p);
//Utility.getPizzaItem(p);
} else {
SharedPreferences states = getContext().getSharedPreferences("states", Context.MODE_PRIVATE);
SharedPreferences.Editor editor3 = states.edit();
finalHolder.edit.setVisibility(View.GONE);
finalHolder.edit.setEnabled(false);
finalHolder.edit.setText("");
editor3.putBoolean("holder.chkBox" + finalHolder.planetName.getText().toString(), false);
editor3.commit();
}
/* SharedPreferences states = getContext().getSharedPreferences("states", Context.MODE_PRIVATE);
SharedPreferences.Editor editor = states.edit();
editor.apply();*/
}
});
/*holder.chkBox.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if (finalHolder.chkBox.isChecked()) {
finalHolder.edit.setVisibility(View.VISIBLE);
finalHolder.edit.setEnabled(true);
SharedPreferences states = getContext().getSharedPreferences("states", Context.MODE_PRIVATE);
SharedPreferences.Editor editor = states.edit();
editor.putBoolean("holder.chkBox", true);
//pizzaSelected.put(p.getId(), p);
System.out.println(p.getId());
} else {
finalHolder.edit.setVisibility(View.GONE);
finalHolder.edit.setEnabled(false);
finalHolder.edit.setText(null);
pizzaSelected.remove(p.getId());
}
}
});
*/
finalHolder.edit.addTextChangedListener(new TextWatcher() {
@Override
public void beforeTextChanged(CharSequence s, int start, int count, int after) {
}
@Override
public void onTextChanged(CharSequence s, int start, int before, int count) {
}
@Override
public void afterTextChanged(Editable s) {
p.setQuantità(finalHolder.edit.getText().toString().trim());
SharedPreferences states = getContext().getSharedPreferences("states", Context.MODE_PRIVATE);
SharedPreferences.Editor editor = states.edit();
editor.putString("finalHolder.edit" + finalHolder.planetName.getText().toString(), finalHolder.edit.getText().toString().trim());
editor.commit();
}
});
//holder.planetName.setText(p.getName());
//holder.distView.setText("" + p.getDistance());
//holder.valuta.setText("" + p.getValuta());
// holder.chkBox.setChecked(p.isSelected());
// holder.chkBox.setTag(p);
// holder.edit.setEnabled(false);
// holder.id.setId(p.getId());
return row;
}
ArrayList<Planet> getBox() {
ArrayList<Planet> box = new ArrayList<Planet>();
for (Planet p : planetList) {
if (p.isSelected())
box.add(p);
}
return box;
}
}
行星适配器的碎片：
public class MyListFragment extends Fragment implements
android.widget.CompoundButton.OnCheckedChangeListener {
ListView lv;
ArrayList<Planet> planetList;
PlanetAdapter plAdapter;
BirraAdapter biAdapter;
PlanetAdapter.PlanetHolder holder;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
ViewGroup rootView = (ViewGroup) inflater.inflate(R.layout.fragment_list2, container, false);
/*Button mButton = (Button) rootView.findViewById(R.id.button);
mButton.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
showResult(v);
}
});*/
//return inflater.inflate(R.layout.fragment_list2, container, false);
return rootView;
}
@Override
public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
lv = (ListView)getView().findViewById(R.id.listview);
displayPlanetList();
}
private void displayPlanetList() {
planetList = new ArrayList<Planet>();
planetList.add(new Planet("Margherita", 6, "€",1));
planetList.add(new Planet("Diavola", 7,"€",2));
planetList.add(new Planet("Bufalina", 5,"€",3));
planetList.add(new Planet("Marinara", 5, "€",4));
planetList.add(new Planet("Viennese", 4, "€", 5));
plAdapter = new PlanetAdapter(planetList, getActivity()) {
@Override
public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
int pos = lv.getPositionForView(buttonView);
if (pos != ListView.INVALID_POSITION) {
Planet p = planetList.get(pos);
p.setSelected(isChecked);
/*Toast.makeText(
getActivity(),
"Clicked on Pizza: " + p.getName() + ". State: is "
+ isChecked, Toast.LENGTH_SHORT).show();*/
}
}
};
lv.setAdapter(plAdapter);
}
}
三片：
public class ThreeFragment extends Fragment implements
android.widget.CompoundButton.OnCheckedChangeListener {
ListView lv2;
ArrayList<Birra> birraList;
BirraAdapter biAdapter;
PlanetAdapter plAdapter;
Planet p;
BirraAdapter.BirraHolder birraHolder;
PlanetAdapter.PlanetHolder holder;
public ThreeFragment() {
// Required empty public constructor
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
ViewGroup rootView = (ViewGroup) inflater.inflate(R.layout.fragment_three, container, false);
Button mButton = (Button) rootView.findViewById(R.id.button2);
mButton.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
showResult(v);
}
});
//return inflater.inflate(R.layout.fragment_list2, container, false);
return rootView;
}
@Override
public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
lv2 = (ListView) getView().findViewById(R.id.listview2);
displayBirraList();
}
private void displayBirraList() {
birraList = new ArrayList<Birra>();
birraList.add(new Birra("Paulaner", 6, "€"));
birraList.add(new Birra("Forst", 7, "€"));
birraList.add(new Birra("Peroni", 5, "€"));
birraList.add(new Birra("Corona", 5, "€"));
birraList.add(new Birra("Nastro Azzurro", 4, "€"));
biAdapter = new BirraAdapter(birraList, getContext()) {
@Override
public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
int pos = lv2.getPositionForView(buttonView);
if (pos != ListView.INVALID_POSITION) {
Birra b = birraList.get(pos);
b.setSelected(isChecked);
/*Toast.makeText(
getActivity(),
"Clicked on Pizza: " + p.getName() + ". State: is "
+ isChecked, Toast.LENGTH_SHORT).show();*/
}
}
};
lv2.setAdapter(biAdapter);
}
public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
/*int pos = lv.getPositionForView(buttonView);
if (pos != ListView.INVALID_POSITION) {
Planet p = planetList.get(pos);
p.setSelected(isChecked);
*//**//**//**//*Toast.makeText(
getActivity(),
"Clicked on Planet: " + p.getName() + ". State: is "
+ isChecked, Toast.LENGTH_SHORT).show();*//**//**//**//*
}
*/
}
public void showResult(View v) {
String result = "Selected Product are :";
int totalAmount = 0;
String c = "";
for (Birra b : biAdapter.getBox()) {
if (b.selected) {
result += "\n" + b.name + " " + b.distance + "€" + "q.tà :" + b.getQuantità();
int quantitaInt = Integer.parseInt(b.getQuantità());
totalAmount += b.distance * quantitaInt;
//a=String.valueOf(totalAmount);
}
}
for (Planet p : plAdapter.getBox()) {
if (p.isSelected()) {
result += "\n" + p.getName() + " " + p.getDistance() + "€" + "q.tà :" + p.getQuantità();
int quantitaInt = Integer.parseInt(p.getQuantità());
//totalAmount2+=p.distance * quantitaInt;
//z=String.valueOf(totalAmount2);
}
for (Birra b : biAdapter.getBox()) {
if (b.selected) {
result += "\n" + b.name + " " + b.distance + "€" + "q.tà :" + b.getQuantità();
int quantitaInt = Integer.parseInt(b.getQuantità());
totalAmount += b.distance * quantitaInt;
c = String.valueOf(totalAmount);
}
}
Toast.makeText(getActivity(), result + "\n" + "Total Amount:=" + totalAmount + "€", Toast.LENGTH_LONG).show();
Bundle bun2 = new Bundle();
bun2.putString("scelta2", result);
TwoFragment fgsearch2 = new TwoFragment();
fgsearch2.setArguments(bun2);
android.support.v4.app.FragmentTransaction transaction2 = getActivity().getSupportFragmentManager().beginTransaction();
transaction2.replace(R.id.content_main, fgsearch2);
transaction2.commit();
Bundle bun = new Bundle();
bun.putString("totale2", c);
TwoFragment fgsearch = new TwoFragment();
fgsearch.setArguments(bun);
android.support.v4.app.FragmentTransaction transaction = getActivity().getSupportFragmentManager().beginTransaction();
transaction.replace(R.id.content_main2, fgsearch);
transaction.commit();
}
}
}
这是我的APP：
答案 0 :(得分：0)
PlAdapter尚未初始化。您必须在此行之前初始化它：for (Planet p : plAdapter.getBox()) {因此空指针异常
最好在OnCreateView（）
