我在卡片视图中设置文字有问题。我有3名活动家。第1次活动是显示完成数据的编辑文本的列表，第2活动人员下次acttivty 3概要点击buton去MainActivty。单击MainActitvty时显示错误。
04-05 09:21:06.879 1035-1035/magdalena.pl.callmistake E/AndroidRuntime: FATAL EXCEPTION: main
Process: magdalena.pl.callmistake, PID: 1035
java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String magdalena.pl.callmistake.Person.getName()' on a null object reference
at magdalena.pl.callmistake.PersonAdapter.onBindViewHolder(PersonAdapter.java:41)
at magdalena.pl.callmistake.PersonAdapter.onBindViewHolder(PersonAdapter.java:18)
at android.support.v7.widget.RecyclerView$Adapter.onBindViewHolder(RecyclerView.java:6356)
at android.support.v7.widget.RecyclerView$Adapter.bindViewHolder(RecyclerView.java:6389)
at android.support.v7.widget.RecyclerView$Recycler.tryBindViewHolderByDeadline(RecyclerView.java:5335)
at android.support.v7.widget.RecyclerView$Recycler.tryGetViewHolderForPositionByDeadline(RecyclerView.java:5598)
我的PersonAdapter
public class PersonAdapter extends RecyclerView.Adapter<PersonAdapter.PersonViewHolder> {
public List<Person> personList = new ArrayList<>();
Person person;
private LayoutInflater layoutInflater;
public PersonAdapter(LayoutInflater layoutInflater) {
this.layoutInflater = layoutInflater;
}
@Override
public PersonViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View view = LayoutInflater.
from(parent.getContext()).inflate(R.layout.item_card, parent, false);
return new PersonViewHolder(view);
}
@Override
public void onBindViewHolder(PersonViewHolder holder, int position) {
person = personList.get(position);
holder.name.setText(person.getName());
holder.surname.setText(person.getSurname());
}
@Override
public int getItemCount() {
return personList.size();
}
public void addPerson(Person person) {
int position = getItemCount();
personList.add(position, person);
notifyDataSetChanged();
}
public class PersonViewHolder extends RecyclerView.ViewHolder {
public TextView name, surname;
public PersonViewHolder(View itemView) {
super(itemView);
name = (TextView)itemView.findViewById(R.id.person_name);
surname = (TextView)itemView.findViewById(R.id.person_surname);
}
}
}
class Person
public class Person implements Parcelable
{
private String name;
private String surname;
private String email;
private String phone;
private String description;
protected Person(Parcel in) {
name = in.readString();
surname = in.readString();
email = in.readString();
phone = in.readString();
description = in.readString();
}
public Person(String name, String surname, String email, String phone, String description) {
this.name = name;
this.surname = surname;
this.email = email;
this.phone = phone;
this.description = description;
}
public String setName(String name) {
this.name = name;
return null;
}
public String getSurname() {
return surname;
}
public String setSurname(String surname) {
this.surname = surname;
return null;
}
public String getEmail() {
return email;
}
public void setEmail(String email) {
this.email = email;
}
public String getPhone() {
return phone;
}
public void setPhone(String phone) {
this.phone = phone;
}
public String getDescription() {
return description;
}
public void setDescription(String description) {
this.description = description;
}
public static Creator<Person> getCREATOR() {
return CREATOR;
}
public static final Creator<Person> CREATOR = new Creator<Person>() {
@Override
public Person createFromParcel(Parcel in) {
return new Person(in);
}
@Override
public Person[] newArray(int size) {
return new Person[size];
}
};
public String getName() {
return name;
}
@Override
public int describeContents() {
return 0;
}
@Override
public void writeToParcel(Parcel parcel, int i) {
parcel.writeString(name);
parcel.writeString(surname);
parcel.writeString(email);
parcel.writeString(phone);
parcel.writeString(description);
}
}
有什么问题？
答案 0 :(得分：0)
显然，在onBindViewHolder方法中，person对象为null。并且您尝试在null引用上调用getName（）方法。所以它导致错误。确保对Person对象有有效的引用。
答案 1 :(得分：0)
您正在将人员添加到
的personListpublic void addPerson(Person person) {
int position = getItemCount();
personList.add(position, person);
notifyDataSetChanged();
}
这就是你打电话的原因
person = personList.get(position);
返回null
试试这个
public void addPerson(Person person) {
if(person==null){
Log.e("error","person is null");
return;
}
int position = getItemCount();
personList.add(position, person);
notifyDataSetChanged();
}
答案 2 :(得分：0)
final Person person = personList.get(position);
holder.name.setText(person.getName());
答案 3 :(得分：0)
从附件logs开始，您似乎从适配器的NullPointerException拨打Person.getName()时收到onBindViewHolder()。
java.lang.NullPointerException：尝试调用虚方法 'null。上的java.lang.String magdalena.pl.callmistake.Person.getName（）' 对象参考
<强>解决方案：
更新PersonAdapter，如下所示：
public class PersonAdapter extends RecyclerView.Adapter<PersonAdapter.PersonViewHolder> {
Context context;
private LayoutInflater layoutInflater;
// Person List
public List<Person> personList;
public PersonAdapter(Context context, List<Person> persons) {
this.context = context;
this.personList = persons;
layoutInflater= LayoutInflater.from(context);
}
@Override
public PersonViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View view = layoutInflater.inflate(R.layout.item_card, parent, false);
// View holder
PersonViewHolder holder = new PersonViewHolder(view);
return holder;
}
@Override
public void onBindViewHolder(PersonViewHolder holder, int position) {
// Person
Person person = personList.get(position);
holder.name.setText(person.getName());
holder.surname.setText(person.getSurname());
}
@Override
public int getItemCount() {
return personList.size();
}
public void addPerson(Person person) {
int position = getItemCount();
personList.add(position, person);
notifyDataSetChanged();
}
public class PersonViewHolder extends RecyclerView.ViewHolder {
public TextView name, surname;
public PersonViewHolder(View itemView) {
super(itemView);
name = (TextView) itemView.findViewById(R.id.person_name);
surname = (TextView) itemView.findViewById(R.id.person_surname);
}
}
}
在Activity执行此操作：
..........
.................
Context mContext;
// RecyclerView
RecyclerView recyclerView;
PersonAdapter personAdapter;
RecyclerView.LayoutManager layoutManager;
// Values
List<Person> listPerson;
@Override
protected void onCreate(Bundle savedInstanceState) {
.......
............
// Context
mContext = this;
recyclerView = (RecyclerView) findViewById(R.id.recycler_view);
// Set your recyclerView layout manager
// Person List
listPerson = new ArrayList<Person>();
// Add some person data to list from API call or from Database
// Here I added some for test purpose
listPerson.add(new Person("Hello Android", "Android", "google@gmail.com", "21132342423", "Lorem ipsum"));
listPerson.add(new Person("Hello Android", "Android", "google@gmail.com", "21132342423", "Lorem ipsum"));
// specify an adapter
personAdapter = new PersonAdapter(mContext, listPerson);
recyclerView.setAdapter(personAdapter);
}
...............
...........................
希望这会对你有帮助〜
答案 4 :(得分：-2)
首先传递您调用此适配器的数据。
adapter = new PersonAdapter(getContext(),(ArrayList<Person>) list);
使用arraylist.method访问类方法。
holder.name.setText(person.personList(position).getName());