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私はデータベースにリストの詳細のためのアプリを開発しています。リスティングは機能していません。それはログとして大丈夫と表示されています。なぜ私のrecyclerlerview listlingが機能していないのですか？ bean1 = new Bean（cn.getName（）、cn.getNumber（）、cn.getSpeeddial（））を使用しているときにエラーが表示されます。Android recyleview listing with database does not working with
マイコードを以下に示します。
SpeedDialViewActivity.java
public class SpeedDialViewActivity extends AppCompatActivity {
private List<Bean> beanList = new ArrayList<>();
private RecyclerView recyclerView;
private ViewAdapter mAdapter;
Context context;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_speed_dial_view);
recyclerView = (RecyclerView) findViewById(R.id.recycler_view);
mAdapter = new ViewAdapter(beanList);
RecyclerView.LayoutManager mLayoutManager = new LinearLayoutManager(getApplicationContext());
recyclerView.setLayoutManager(mLayoutManager);
recyclerView.setItemAnimator(new DefaultItemAnimator());
recyclerView.setAdapter(mAdapter);
prepareData();
}
private void prepareData() {
DatabaseHandler handler = new DatabaseHandler(getApplicationContext());
Log.d("Reading: ", "Reading all contacts..");
List<Bean> beanList = handler.getAllContacts();
//Cursor cursor = (Cursor) handler.getAllContacts();
//Bean bean1;
for (Bean cn : beanList) {
String log = "Id: " + cn.getId() + " ,Name: " + cn.getName() + " ,Phone: " + cn.getNumber();
// Writing Contacts to log
Log.d("Name: ", log);
// bean1 = new Bean(cn.getName(), cn.getNumber(), cn.getSpeeddial()); // Error occurring
// beanList.add(bean1);
}
}
}
DatabaseHandler.java
public class DatabaseHandler extends SQLiteOpenHelper {
private static final int DATABASE_VERSION = 1;
private static final String DATABASE_NAME = "speeddial";
private static final String TABLE_CONTACTS = "contacts";
private static final String KEY_ID = "id";
private static final String KEY_NAME = "name";
private static final String KEY_PH_NO = "phone_number";
private static final String KEY_SPEED_DIAL = "speed_dial_number";
public DatabaseHandler(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db) {
String CREATE_CONTACTS_TABLE = "CREATE TABLE " + TABLE_CONTACTS + "("
+ KEY_ID + " INTEGER PRIMARY KEY," + KEY_NAME + " TEXT,"
+ KEY_PH_NO + " TEXT" + KEY_SPEED_DIAL + " TEXT" + ")";
db.execSQL(CREATE_CONTACTS_TABLE);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// Drop older table if existed
db.execSQL("DROP TABLE IF EXISTS " + TABLE_CONTACTS);
// Create tables again
onCreate(db);
}
void addContact(Bean bean) {
SQLiteDatabase db = this.getWritableDatabase();
ContentValues values = new ContentValues();
values.put(KEY_NAME, bean.getName()); // Contact Name
values.put(KEY_PH_NO, bean.getNumber()); // Contact Phone
values.put(KEY_PH_NO, bean.getSpeeddial()); // Contact Phone
// Inserting Row
db.insert(TABLE_CONTACTS, null, values);
db.close(); // Closing database connection
}
Bean getBean(int id) {
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor = db.query(TABLE_CONTACTS, new String[] { KEY_ID,
KEY_NAME, KEY_PH_NO }, KEY_ID + "=?",
new String[] { String.valueOf(id) }, null, null, null, null);
if (cursor != null)
cursor.moveToFirst();
Bean bean = new Bean(Integer.parseInt(cursor.getString(0)),cursor.getString(1), cursor.getString(2), cursor.getString(3));
// return contact
return bean;
}
public List<Bean> getAllContacts() {
List<Bean> contactList = new ArrayList<Bean>();
// Select All Query
String selectQuery = "SELECT * FROM " + TABLE_CONTACTS;
SQLiteDatabase db = this.getWritableDatabase();
Cursor cursor = db.rawQuery(selectQuery, null);
// looping through all rows and adding to list
if (cursor.moveToFirst()) {
do {
Bean contact = new Bean();
contact.setId(Integer.parseInt(cursor.getString(0)));
contact.setName(cursor.getString(1));
contact.setNumber(cursor.getString(2));
// Adding contact to list
contactList.add(contact);
} while (cursor.moveToNext());
}
// return contact list
return contactList;
}
}
ViewAdapter.java
public class ViewAdapter extends RecyclerView.Adapter<ViewAdapter.MyViewHolder> {
private List<Bean> beanList;
public class MyViewHolder extends RecyclerView.ViewHolder {
public TextView name, number, speeddial_number;
public MyViewHolder(View view) {
super(view);
name = (TextView) view.findViewById(R.id.name);
number = (TextView) view.findViewById(R.id.number);
speeddial_number = (TextView) view.findViewById(R.id.speeddialNumber);
}
}
public ViewAdapter(List<Bean> beanList){
this.beanList = beanList;
}
@Override
public ViewAdapter.MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View itemView = LayoutInflater.from(parent.getContext()).inflate(R.layout.speeddial_list_row, parent, false);
return new MyViewHolder(itemView);
}
@Override
public void onBindViewHolder(ViewAdapter.MyViewHolder holder, int position) {
Bean bean = beanList.get(position);
holder.name.setText(bean.getName());
holder.number.setText(bean.getNumber());
holder.speeddial_number.setText(bean.getSpeeddial());
}
@Override
public int getItemCount() {
return beanList.size();
}
}
Bean.java
public class Bean{
private int id;
private String name;
private String number;
private String speeddial;
public Bean(int id, String name, String number, String speeddial) {
this.id=id;
this.name=name;
this.number=number;
this.speeddial=speeddial;
}
public Bean(String name, String number, String speeddial) {
this.name=name;
this.number=number;
this.speeddial=speeddial;
}
public Bean() {
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getNumber() {
return number;
}
public void setNumber(String number) {
this.number = number;
}
public String getSpeeddial() {
return speeddial;
}
public void setSpeeddial(String speeddial) {
this.speeddial = speeddial;
}
}
エラーがjava.lang.RuntimeExceptionある：アクティビティを開始できませんComponentInfo {com.app.appname/com.app.appname}：java
.util.ConcurrentModificationExceptionは、あなたがリストにフェッチされている連絡先を追加しないと、データ・セットが変更通知行っていない私に
エラーログを投稿してください。 –
java.lang.RuntimeException：アクティビティを開始できませんComponentInfo {com.app.appname/com.app.appname}：java.util.ConcurrentModificationException –