Develop Reference

How to cast the value of SQLiteDatabase.execSQL to a String?

I'm developing a small android notes app using java. Everything seems to be working fine except that I'm getting an error while trying to cast the instance SQLiteDatabase.execSql obj to a String. The purpose of doing this is that, it will allow user to update their data. In the custom adapter class (obBind method) I've set a tag, which means I've the id of each itemView even in my MainActivity. What I want it to do is when a user left swipes a particular item then his/her data should be set (editText.setText) in the edittext and if he/she clicks on the add button, the data should be updated.
Please refer to the codes for better understand-ability
CustomAdapter Class:
package com.example.myapplication20;
import android.content.Context;
import android.database.Cursor;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;
public class CustomAdapter extends RecyclerView.Adapter<CustomAdapter.ViewHolder> {
Context mContext;
Cursor mCursor;
CustomAdapter (Context context, Cursor cursor) {
mContext = context;
mCursor = cursor;
}
#NonNull
#Override
public CustomAdapter.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
LayoutInflater inflater = LayoutInflater.from(mContext);
View view = inflater.inflate(R.layout.single_item_layout, parent, false);
return new ViewHolder(view);
}
#Override
public void onBindViewHolder(CustomAdapter.ViewHolder holder, int position) {
if (!mCursor.moveToPosition(position)) {
return;
}
String value = mCursor.getString(mCursor.getColumnIndex(TableDetailsClass.Collection.TABLE_COLUMN));
Long id = mCursor.getLong(mCursor.getColumnIndex(TableDetailsClass.Collection._ID));
holder.mTextView.setText(value);
holder.itemView.setTag(id);
}
#Override
public int getItemCount() {
return mCursor.getCount();
}
public class ViewHolder extends RecyclerView.ViewHolder {
TextView mTextView;
TextView uTextView;
public ViewHolder(View itemView) {
super(itemView);
mTextView = itemView.findViewById(R.id.textView);
uTextView = itemView.findViewById(R.id.updateTextView);
}
}
public void swapCursor (Cursor newCursor) {
if (mCursor != null) {
mCursor.close();
}
mCursor = newCursor;
if (newCursor != null) {
notifyDataSetChanged();
}
}
}
MainActivity Class:
package com.example.myapplication20;
import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import androidx.recyclerview.widget.ItemTouchHelper;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;
import android.content.ContentValues;
import android.content.Intent;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.view.CollapsibleActionView;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;
public class MainActivity extends AppCompatActivity {
private EditText mEditText;
private Button addButton;
private RecyclerView mRecyclerView;
private SQLiteDatabase mDataBase;
MyOpenHelperClass myOpenHelperClass;
CustomAdapter mCustomAdapter;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
myOpenHelperClass = new MyOpenHelperClass(this);
mDataBase = myOpenHelperClass.getWritableDatabase();
mEditText = findViewById(R.id.editText);
addButton = findViewById(R.id.button);
mCustomAdapter = new CustomAdapter(this, getAllItems());
mRecyclerView = findViewById(R.id.recyclerView);
mRecyclerView.setLayoutManager(new LinearLayoutManager(this));
mRecyclerView.setAdapter(mCustomAdapter);
addButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
addItems();
}
});
// Swipe delete
new ItemTouchHelper(new ItemTouchHelper.SimpleCallback(0, ItemTouchHelper.RIGHT) {
#Override
public boolean onMove(#NonNull RecyclerView recyclerView, #NonNull RecyclerView.ViewHolder viewHolder, #NonNull RecyclerView.ViewHolder target) {
return false;
}
#Override
public void onSwiped(#NonNull RecyclerView.ViewHolder viewHolder, int direction) {
removeItem( (Long) viewHolder.itemView.getTag());
}
}).attachToRecyclerView(mRecyclerView);
new ItemTouchHelper(new ItemTouchHelper.SimpleCallback(0, ItemTouchHelper.LEFT) {
#Override
public boolean onMove(#NonNull RecyclerView recyclerView, #NonNull RecyclerView.ViewHolder viewHolder, #NonNull RecyclerView.ViewHolder target) {
return false;
}
#Override
public void onSwiped(#NonNull RecyclerView.ViewHolder viewHolder, int direction) {
updateItem( (Long) viewHolder.itemView.getTag());
}
}).attachToRecyclerView(mRecyclerView);
}
private void addItems () {
if (mEditText.getText().toString().trim().length() == 0) {
return;
}
String textToBeAdded = mEditText.getText().toString();
ContentValues cv = new ContentValues();
cv.put(TableDetailsClass.Collection.TABLE_COLUMN, textToBeAdded);
mDataBase.insert(TableDetailsClass.Collection.TABLE_NAME, null, cv);
mCustomAdapter.swapCursor(getAllItems());
mEditText.getText().clear();
}
public Cursor getAllItems () {
return mDataBase.query(TableDetailsClass.Collection.TABLE_NAME,
null,
null,
null,
null,
null,
TableDetailsClass.Collection.TIMESTAMP + " DESC"
);
}
public void removeItem (Long id) {
mDataBase.delete(TableDetailsClass.Collection.TABLE_NAME,
TableDetailsClass.Collection._ID + "=" + id, null);
mCustomAdapter.swapCursor(getAllItems());
Toast.makeText(this, "Item deleted!", Toast.LENGTH_SHORT).show();
}
public void updateItem (long id) {
String val = mDataBase.execSQL("SELECT * FROM " + TableDetailsClass.Collection.TABLE_NAME + " WHERE " +
TableDetailsClass.Collection._ID + "=" + id);
mEditText.setText(val); // The line I'm getting the error in. Says cannot cast void to string.
ContentValues cv = new ContentValues();
cv.put(TableDetailsClass.Collection.TABLE_COLUMN, mEditText.getText().toString());
mDataBase.update(TableDetailsClass.Collection.TABLE_NAME, cv,
TableDetailsClass.Collection._ID + "=" + id, null);
mCustomAdapter.swapCursor(getAllItems());
}
}
SQLiteOpenHelper Class:
package com.example.myapplication20;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import androidx.annotation.Nullable;
public class MyOpenHelperClass extends SQLiteOpenHelper {
public static final String DATABASE_NAME = "myapp.db";
public static final int DATABASE_VERSION = 1;
public MyOpenHelperClass(#Nullable Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
#Override
public void onCreate(SQLiteDatabase db) {
String SQL_CREATE_QUERY = "CREATE TABLE " +
TableDetailsClass.Collection.TABLE_NAME + "(" +
TableDetailsClass.Collection._ID + " INTEGER PRIMARY KEY AUTOINCREMENT, " +
TableDetailsClass.Collection.TABLE_COLUMN + " TEXT NOT NULL, " +
TableDetailsClass.Collection.TIMESTAMP + " TIMESTAMP DEFAULT CURRENT_TIMESTAMP" + ");";
db.execSQL(SQL_CREATE_QUERY);
}
#Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL("DROP TABLE IF EXISTS " + TableDetailsClass.Collection.TABLE_NAME);
onCreate(db);
}
}
Any kind of help will be really appreciated.

public void updateItem (long id) {
Cursor cursor = mDataBase.rawQuery("SELECT * FROM " + TableDetailsClass.Collection.TABLE_NAME + " WHERE " +
TableDetailsClass.Collection._ID + "= ?", new String[]{String.valueOf(id)});
if (cursor != null && cursor.moveToFirst()) {
String val = cursor.getString(cursor.getColumnIndex(TableDetailsClass.Collection.TABLE_COLUMN));
mEditText.setText(val);
cursor.close();
}
...
}

Java: How to update the Recycler View every time I delete an item?

I seem to be stuck with this problem where I want to update the Recycler View in real-time. Meaning I want the recycler view to update its list when a user swipes to delete a row.
As you can see in the code below I have tried to use NotifyDataSetChange() in the DatabaseAdapter java class but I only get the error "RecyclerViewAdapter.notifyDataSetChanged() on a null object reference".
I have both googled the error above and how to update Recycle view in real-time but none of the solutions I found worked. Please help me because I am losing it with this problem.
NamesAdapter.Java
package com.example.myapplication.ui;
import android.content.Context;
import android.database.Cursor;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
import android.widget.Toast;
import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;
import com.example.myapplication.DatabaseAdapter;
import com.example.myapplication.R;
import org.w3c.dom.NameList;
import java.util.ArrayList;
import java.util.List;
public class NamesAdapter extends RecyclerView.Adapter<NamesAdapter.ViewHolder> {
Context context;
List<Names> namesList;
RecyclerView rvPrograms;
final View.OnClickListener onClickListener = new MyOnClickListner();
public static class ViewHolder extends RecyclerView.ViewHolder{
TextView rowID;
TextView rowName;
TextView rowAmount;
TextView rowDate;
public ViewHolder(#NonNull View itemView) {
super(itemView);
//Store the item sub-views in member variables
rowID = itemView.findViewById(R.id.idTextView);
rowName = itemView.findViewById(R.id.nameTextView);
rowAmount = itemView.findViewById(R.id.amountEditText);
rowDate = itemView.findViewById(R.id.dateTextView);
}
}
public NamesAdapter(Context context, List<Names> namesList, RecyclerView rvPrograms){
this.context = context;
this.namesList= namesList;
this.rvPrograms = rvPrograms;
}
#NonNull
#Override
public NamesAdapter.ViewHolder onCreateViewHolder(#NonNull ViewGroup viewGroup, int viewType) {
LayoutInflater inflater = LayoutInflater.from(context);
View view = inflater.inflate(R.layout.recycler_list, viewGroup, false);
view.setOnClickListener(onClickListener);
ViewHolder viewHolder = new ViewHolder(view);
return viewHolder;
}
#Override
public void onBindViewHolder(#NonNull NamesAdapter.ViewHolder holder, int i) {
Names name = namesList.get(i);
holder.rowID.setText(""+name.getId());
holder.rowName.setText(name.getName());
holder.rowAmount.setText(name.getAmount());
holder.rowDate.setText(name.getDate());
holder.itemView.setTag(name.getId());
}
#Override
public int getItemCount() {
return namesList.size();
}
private class MyOnClickListner implements View.OnClickListener {
#Override
public void onClick(View v) {
int itemPosition = rvPrograms.getChildLayoutPosition(v);
String item = namesList.get(itemPosition).getName();
Toast.makeText(context, item, Toast.LENGTH_SHORT).show();
}
}
}
DatabaseAdapter.Java
package com.example.myapplication;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.widget.Toast;
import androidx.annotation.Nullable;
import com.example.myapplication.ui.Names;
import com.example.myapplication.ui.NamesAdapter;
import java.util.ArrayList;
import java.util.List;
public class DatabaseAdapter {
DatabaseHelper helper;
SQLiteDatabase db;
List<Names> namesList = new ArrayList<>();
NamesAdapter na;
public DatabaseAdapter(Context context) {
helper = new DatabaseHelper(context);
db = helper.getWritableDatabase();
}
public int deleteData(String name){
String whereArgs[] = {name};
int count = db.delete(DatabaseHelper.Table_Name, DatabaseHelper.Key_Name+ "=?", whereArgs);
return count;
}
public int removeItem (long id){
int count = db.delete(DatabaseHelper.Table_Name, DatabaseHelper.Key_ID+ "="+ id, null);
//na.notifyDataSetChanged();
return count;
}
public int updateAmount(String name, String amount){
ContentValues contentValues = new ContentValues();
contentValues.put(DatabaseHelper.Key_Amount, amount);
String whereArgs[] = {name};
int count = db.update(DatabaseHelper.Table_Name, contentValues, DatabaseHelper.Key_Name + "=?", whereArgs);
return count;
}
public String searchData(String sname){
String columns[] = {DatabaseHelper.Key_Name, DatabaseHelper.Key_Amount};
String selectionArgs[] = {sname};
Cursor cursor = db.query(DatabaseHelper.Table_Name, columns, DatabaseHelper.Key_Name + "=?", selectionArgs, null, null, null);
StringBuffer buffer = new StringBuffer();
while (cursor.moveToNext()){
int index1 = cursor.getColumnIndex(DatabaseHelper.Key_Name);
int index2 = cursor.getColumnIndex(DatabaseHelper.Key_Amount);
String name = cursor.getString(index1);
String amount = cursor.getString(index2);
buffer.append(name + " " + amount + "\n");
}
return buffer.toString();
}
// This is for the Toast dispaly
public String getAllData(){
String columns[] = {DatabaseHelper.Key_ID, DatabaseHelper.Key_Name, DatabaseHelper.Key_Amount};
Cursor cursor = db.query(DatabaseHelper.Table_Name, columns, null, null, null, null, null, null );
StringBuffer buffer = new StringBuffer();
while (cursor.moveToNext()){
int index1 = cursor.getColumnIndex(DatabaseHelper.Key_ID);
int rowid = cursor.getInt(index1);
int index2 = cursor.getColumnIndex(DatabaseHelper.Key_Name);
String name = cursor.getString(index2);
int index3 = cursor.getColumnIndex(DatabaseHelper.Key_Amount);
int amount = cursor.getInt(index3);
buffer.append(rowid + " " + name + " " + amount + "\n");
}
return buffer.toString();
}
public List<Names> getAllNames(){
String columns[] = {DatabaseHelper.Key_ID, DatabaseHelper.Key_Name, DatabaseHelper.Key_Amount, DatabaseHelper.Key_Date};
Cursor cursor = db.query(DatabaseHelper.Table_Name, columns, null, null, null, null, DatabaseHelper.Key_ID+" DESC",null );
while (cursor.moveToNext()){
int index1 = cursor.getColumnIndex(DatabaseHelper.Key_ID);
int rowid = cursor.getInt(index1);
int index2 = cursor.getColumnIndex(DatabaseHelper.Key_Name);
String name = cursor.getString(index2);
int index3 = cursor.getColumnIndex(DatabaseHelper.Key_Amount);
Double amount = cursor.getDouble(index3);
int index4 = cursor.getColumnIndex(DatabaseHelper.Key_Date);
String date = cursor.getString(index4);
Names names = new Names(rowid, name, amount, date);
namesList.add(names);
}
return namesList;
}
public long insertData (String name, Double amount, String date){
ContentValues contentValues = new ContentValues();
contentValues.put(DatabaseHelper.Key_Name, name);
contentValues.put(DatabaseHelper.Key_Amount, amount);
contentValues.put(DatabaseHelper.Key_Date, date);
long id = db.insert(DatabaseHelper.Table_Name, null ,contentValues);
return id;
}
private static class DatabaseHelper extends SQLiteOpenHelper {
private static final String Database_Name = "Demoze.db";
private static final String Table_Name = "salary";
private static final int Database_Version= 10;
private static final String Key_ID = "_id";
private static final String Key_Name = "name";
private static final String Key_Amount = "amount";
private static final String Key_Date = "date";
private static final String Create_table = "create table "+Table_Name+
" ("+Key_ID+" integer primary key autoincrement, "+Key_Name+
" text, "+Key_Amount+ " real, "+Key_Date+" text)";
private static final String Table_Drop = "drop table if exists "+Table_Name;
private Context context;
public DatabaseHelper(#Nullable Context context) {
super(context, Database_Name, null, Database_Version);
this.context = context;
Toast.makeText(context, "Constructor Called", Toast.LENGTH_SHORT).show();
}
#Override
public void onCreate(SQLiteDatabase db) {
try {
db.execSQL(Create_table);
Toast.makeText(context, "OnCreate Called", Toast.LENGTH_SHORT).show();
} catch (SQLException e){
Toast.makeText(context, ""+e, Toast.LENGTH_SHORT).show();
}
}
#Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
try {
Toast.makeText(context, "OnUpgrade Called", Toast.LENGTH_SHORT).show();
db.execSQL(Table_Drop);
onCreate(db);
} catch (SQLException e) {
Toast.makeText(context, "" + e, Toast.LENGTH_SHORT).show();
}
}
}
}
SpendingActivity.Java
package com.example.myapplication;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.EditText;
import android.widget.Toast;
import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import androidx.recyclerview.widget.ItemTouchHelper;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;
import com.example.myapplication.ui.Names;
import com.example.myapplication.ui.NamesAdapter;
import java.util.ArrayList;
import java.util.List;
public class SpendingActivity extends AppCompatActivity {
DatabaseAdapter databaseAdapter;
EditText crud;
RecyclerView rvPrograms;
NamesAdapter namesAdapter;
RecyclerView.LayoutManager layoutManager;
List<Names> namesList = new ArrayList<>();
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.spending_list);
databaseAdapter = new DatabaseAdapter(this);
namesList = databaseAdapter.getAllNames();
rvPrograms = findViewById(R.id.rvDBdata);
rvPrograms.setHasFixedSize(true);
layoutManager = new LinearLayoutManager(this);
rvPrograms.setLayoutManager(layoutManager);
namesAdapter = new NamesAdapter(this, namesList, rvPrograms);
rvPrograms.setAdapter(namesAdapter);
new ItemTouchHelper(new ItemTouchHelper.SimpleCallback(0, ItemTouchHelper.LEFT | ItemTouchHelper.RIGHT) {
#Override
public boolean onMove(#NonNull RecyclerView recyclerView, #NonNull RecyclerView.ViewHolder viewHolder, #NonNull RecyclerView.ViewHolder target) {
return false;
}
#Override
public void onSwiped(#NonNull RecyclerView.ViewHolder viewHolder, int direction) {
databaseAdapter.removeItem((long) viewHolder.itemView.getTag());
}
}).attachToRecyclerView(rvPrograms);
crud = findViewById(R.id.crudEditText);
String data = databaseAdapter.getAllData();
Toast.makeText(this, data, Toast.LENGTH_LONG).show();
}
public void Home (View view) {
Intent intent = new Intent(this, MainActivity.class);
startActivity(intent);
}
public void Search (View view){
String name = crud.getText().toString().trim();
String result = databaseAdapter.searchData(name);
Toast.makeText(this, result, Toast.LENGTH_SHORT).show();
}
public void Update (View view) {
String amount = crud.getText().toString().trim();
databaseAdapter.updateAmount("taxi", amount);
}
public void Delete (View view) {
String name = crud.getText().toString().trim();
databaseAdapter.deleteData(name);
}
}

In your NamesAdapter you could expose a method called deleteItem:
public class NamesAdapter extends RecyclerView.Adapter<NamesAdapter.ViewHolder> {
...
public void deleteItem(int position){
namesList.remove(position);
notifyItemRemoved(position);
}
}
Inside of onSwiped() method, you need to call NameAdapter' deleteItem method:
#Override
public void onSwiped(#NonNull RecyclerView.ViewHolder viewHolder, int direction) {
int position = viewHolder.getAdapterPosition();
namesAdapter.deleteItem(position);
databaseAdapter.removeItem((long) viewHolder.itemView.getTag());
}

Recycleview adapterclass
public class MyRecyclerViewAdapter extends RecyclerView.Adapter<MyRecyclerViewAdapter.ViewHolder> {
private List<String> mData;
private LayoutInflater mInflater;
private ItemClickListener mClickListener;
// data is passed into the constructor
MyRecyclerViewAdapter(Context context, List<String> data) {
this.mInflater = LayoutInflater.from(context);
this.mData = data;
}
// inflates the row layout from xml when needed
#Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View view = mInflater.inflate(R.layout.recyclerview_row, parent, false);
return new ViewHolder(view);
}
// binds the data to the TextView in each row
#Override
public void onBindViewHolder(ViewHolder holder, int position) {
String animal = mData.get(position);
holder.myTextView.setText(animal);
}
// total number of rows
#Override
public int getItemCount() {
return mData.size();
}
// stores and recycles views as they are scrolled off screen
public class ViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
TextView myTextView;
ViewHolder(View itemView) {
super(itemView);
myTextView = itemView.findViewById(R.id.tvAnimalName);
itemView.setOnClickListener(this);
}
#Override
public void onClick(View view) {
if (mClickListener != null) mClickListener.onItemClick(view, getAdapterPosition());
}
}
// convenience method for getting data at click position
String getItem(int id) {
return mData.get(id);
}
// allows clicks events to be caught
void setClickListener(ItemClickListener itemClickListener) {
this.mClickListener = itemClickListener;
}
// parent activity will implement this method to respond to click events
public interface ItemClickListener {
void onItemClick(View view, int position);
}
}
MainActivity
public class MainActivity extends AppCompatActivity implements MyRecyclerViewAdapter.ItemClickListener {
MyRecyclerViewAdapter adapter;
ArrayList<String> animalNames
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// data to populate the RecyclerView with
animalNames = new ArrayList<>();
animalNames.add("Horse");
animalNames.add("Cow");
animalNames.add("Camel");
animalNames.add("Sheep");
animalNames.add("Goat");
// set up the RecyclerView
RecyclerView recyclerView = findViewById(R.id.rvAnimals);
recyclerView.setLayoutManager(new LinearLayoutManager(this));
adapter = new MyRecyclerViewAdapter(this, animalNames);
adapter.setClickListener(this);
recyclerView.setAdapter(adapter);
}
#Override
public void onItemClick(View view, int position) {
Toast.makeText(this, "You clicked " + adapter.getItem(position) + " on row number " + position, Toast.LENGTH_SHORT).show();
animalNames.remove(position);
adapter.notifyItemRemoved(position);
}
}

Access a function from another class

i have 4 classes in my app cardclick.java , DatabaseHelper.java , homeframgment.java and recyclerAdapterhomesubjectList.java
I have a function populateArrayList(); in homefragment in which i want to call every time onclick(){present in recyclerAdapterHomesubjectList} is called. can someone help me in achieving that
homefragment::
package com.example.app100.RecylerAdapter;
import android.content.Context;
import android.content.Intent;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;
import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;
import com.example.app100.R;
import com.example.app100.Subject;
import com.example.app100.card_click;
import com.example.app100.ui.home.HomeFragment;
import java.util.ArrayList;
public class RecyclerAdapterHomeSubjectList extends RecyclerView.Adapter<RecyclerView.ViewHolder> {
private ArrayList<Subject> subject;
private Context context;
public RecyclerAdapterHomeSubjectList(ArrayList<Subject> a, Context context){
this.subject = a;
this.context = context;
}
#NonNull
#Override
public ViewHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
LayoutInflater inflater = LayoutInflater.from((parent.getContext()));
View view = inflater.inflate(R.layout.card_home_subject, parent, false);
return new ViewHolder(view) {
};
}
#Override
public void onBindViewHolder(#NonNull RecyclerView.ViewHolder holder, int position) {
ImageView imageView = holder.itemView.findViewById(R.id.home_card_subject_imageview);
switch (position % 3) {
case 2:
imageView.setBackgroundResource(R.drawable.back1);
break;
case 1:
imageView.setBackgroundResource(R.drawable.back2);
break;
case 0:
imageView.setBackgroundResource(R.drawable.back3);
break;
}
Subject data = subject.get(position);
String name = data.subject_name;
TextView subject_name = holder.itemView.findViewById(R.id.home_card_subject_name);
subject_name.setText(name);
}
#Override
public int getItemCount() {
return subject.size();
}
public class ViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener{
ViewHolder(#NonNull View itemView) {
super(itemView);
itemView.setOnClickListener(this);
}
#Override
public void onClick(View v) {
Intent intent = new Intent(context , card_click.class);
intent.putExtra("name" , subject.get(getAdapterPosition()).subject_name);
intent.putExtra("class_good" , subject.get(getAdapterPosition()).class_attended);
intent.putExtra("class_missed" , subject.get(getAdapterPosition()).class_missed);
intent.putExtra("credits",subject.get(getAdapterPosition()).credits);
context.startActivity(intent);
}
}
}
DatabaseHelper::
package com.example.app100;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;
import androidx.annotation.Nullable;
import static androidx.constraintlayout.widget.Constraints.TAG;
public class DatabaseHelper extends SQLiteOpenHelper {
private static final String table_name = "SUBJECT_LIST";
private static final String COL0 = "ID";
private static final String COL1 = "NAME";
private static final String COL2 = "CREDITS";
private static final String COL3 = "CLASS_ATTENDED";
private static final String COL4 = "CLASS_MISSED";
public DatabaseHelper(#Nullable Context context) {
super(context, table_name, null, 6);
}
#Override
public void onCreate(SQLiteDatabase db) {
String CREATE_TABLE = "CREATE TABLE " + table_name + "("+
COL0+ " INTEGER PRIMARY KEY AUTOINCREMENT, " +
COL1 + " TEXT, " +
COL2 + " INTEGER, "+
COL3 + " INTEGER, "+
COL4 + " INTEGER);";
db.execSQL(CREATE_TABLE);
}
#Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL("DROP TABLE IF EXISTS " + table_name);
onCreate(db);
}
public void onDowngrade(SQLiteDatabase db, int oldVersion, int newVersion) {
onUpgrade(db, oldVersion, newVersion);
}
boolean addData(String name, int credit , int good , int bad){
SQLiteDatabase db = this.getWritableDatabase();
ContentValues contentValues = new ContentValues();
contentValues.put(COL1 , name);
contentValues.put(COL2 , credit);
contentValues.put(COL3 , good);
contentValues.put(COL4 , bad);
long result = db.insert(table_name , null , contentValues);
return result != -1;
}
public Cursor getdata(){
SQLiteDatabase db = this.getWritableDatabase();
String query = "SELECT * FROM SUBJECT_LIST;";
return db.rawQuery(query , null);
}
void append_data(String str, String name , int goodbad) {
SQLiteDatabase db = this.getWritableDatabase();
ContentValues contentValues = new ContentValues();
contentValues.put(str, goodbad);
int count = db.update(table_name, contentValues, "NAME = ?", new String[]{name});
Log.d(TAG, "blue button is pressed");
System.out.println(count);
}
}
cardclick:
package com.example.app100;
import androidx.appcompat.app.ActionBar;
import androidx.appcompat.app.AppCompatActivity;
import android.content.Intent;
import android.database.Cursor;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.ImageButton;
import android.widget.ProgressBar;
import android.widget.TextView;
public class card_click extends AppCompatActivity {
TextView attendace_info;
ProgressBar progressBar;
TextView credits;
TextView progress_percent;
int bad;
int good;
Button add;
Button minus;
ImageButton performance;
String name;
DatabaseHelper databaseHelper;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_card_click);
databaseHelper = new DatabaseHelper(this);
ActionBar actionBar = getSupportActionBar();
assert actionBar != null;
actionBar.hide();
performance = findViewById(R.id.card_click_performance_add);
progress_percent = findViewById(R.id.card_click_progress_bar_percent);
attendace_info = findViewById(R.id.card_click_attendance_text);
progressBar = findViewById(R.id.card_click_progress_bar);
credits = findViewById(R.id.card_click_credits_show);
add = findViewById(R.id.card_click_add_button);
minus = findViewById(R.id.card_click_minus_button);
Intent intent = getIntent();
good = intent.getIntExtra("class_good", 0);
bad = intent.getIntExtra("class_missed", 0);
name = intent.getStringExtra("name");
credits.setText(String.valueOf(intent.getIntExtra("credits", 0)));
display();
add.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
good++;
databaseHelper.append_data("CLASS_ATTENDED", name , good);
display();
Cursor data = databaseHelper.getdata();
while(data.moveToNext()){
int a = data.getInt(3);
if( a > 0)
System.out.println("database has been updated");
}
}
});
minus.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
bad++;
databaseHelper.append_data("CLASS_MISSED", name, bad);
display();
Cursor data = databaseHelper.getdata();
while(data.moveToNext()){
int b = data.getInt(4);
if( b > 1)
System.out.println("database has been updated");
}
}
});
performance.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Intent intent1 = new Intent(card_click.this, add_performace.class);
startActivity(intent1);
}
});
}
void display(){
int per = 100;
if(good+bad != 0)
per = (int)(good*100.0)/(good+bad);
String str = "You have atttended "+ (good) +
" out of " + (good + bad) +
" classes";
attendace_info.setText(str);
progressBar.setProgress(per);
progress_percent.setText(String.valueOf(per));
}
}
RecyclerAdapterHomeSubjectList:
package com.example.app100.RecylerAdapter;
import android.content.Context;
import android.content.Intent;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;
import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;
import com.example.app100.R;
import com.example.app100.Subject;
import com.example.app100.card_click;
import com.example.app100.ui.home.HomeFragment;
import java.util.ArrayList;
public class RecyclerAdapterHomeSubjectList extends RecyclerView.Adapter<RecyclerView.ViewHolder> {
private ArrayList<Subject> subject;
private Context context;
public RecyclerAdapterHomeSubjectList(ArrayList<Subject> a, Context context){
this.subject = a;
this.context = context;
}
#NonNull
#Override
public ViewHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
LayoutInflater inflater = LayoutInflater.from((parent.getContext()));
View view = inflater.inflate(R.layout.card_home_subject, parent, false);
return new ViewHolder(view) {
};
}
#Override
public void onBindViewHolder(#NonNull RecyclerView.ViewHolder holder, int position) {
ImageView imageView = holder.itemView.findViewById(R.id.home_card_subject_imageview);
switch (position % 3) {
case 2:
imageView.setBackgroundResource(R.drawable.back1);
break;
case 1:
imageView.setBackgroundResource(R.drawable.back2);
break;
case 0:
imageView.setBackgroundResource(R.drawable.back3);
break;
}
Subject data = subject.get(position);
String name = data.subject_name;
TextView subject_name = holder.itemView.findViewById(R.id.home_card_subject_name);
subject_name.setText(name);
}
#Override
public int getItemCount() {
return subject.size();
}
public class ViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener{
ViewHolder(#NonNull View itemView) {
super(itemView);
itemView.setOnClickListener(this);
}
#Override
public void onClick(View v) {
Intent intent = new Intent(context , card_click.class);
intent.putExtra("name" , subject.get(getAdapterPosition()).subject_name);
intent.putExtra("class_good" , subject.get(getAdapterPosition()).class_attended);
intent.putExtra("class_missed" , subject.get(getAdapterPosition()).class_missed);
intent.putExtra("credits",subject.get(getAdapterPosition()).credits);
context.startActivity(intent);
}
}
}

just import the class name and you can use the function from it. (function and the class should be public to use)

Deleting an item from RecyclerView + SQLite

So I'm trying to delete an item on a cross button. Now it is being deleted from RecyclerView, but goes crazy with SQLite. If I delete one item, it's all good. But when I delete several items, it, as I said, goes crazy and gets deleted items back outta nowhere without deleting anything then.
Here's my DataAdapted.java
import android.content.ContentValues;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.support.annotation.NonNull;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;
import java.util.List;
public class DataAdapter extends RecyclerView.Adapter<DataAdapter.ViewHolder> {
private LayoutInflater inflater;
private List<Booking> bookings;
private String time;
DBHelper dbHelper;
SQLiteDatabase dataBase;
DataAdapter(Context context, List<Booking> bookings) {
this.bookings = bookings;
this.inflater = LayoutInflater.from(context);
}
#NonNull
#Override
public DataAdapter.ViewHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
View view = inflater.inflate(R.layout.list_view, parent, false);
return new ViewHolder(view);
}
#Override
public void onBindViewHolder(#NonNull DataAdapter.ViewHolder holder, int position) {
Booking booking = bookings.get(position);
holder.nameView.setText(booking.getName());
time = booking.getHours() + ":" + booking.getMinutes();
holder.timeView.setText(time);
}
#Override
public int getItemCount() {
return bookings.size();
}
public class ViewHolder extends RecyclerView.ViewHolder {
TextView nameView;
TextView timeView;
ImageView crossImage;
ViewHolder(View view){
super(view);
timeView = view.findViewById(R.id.time_view);
nameView = view.findViewById(R.id.name_view);
crossImage = view.findViewById(R.id.crossImage);
crossImage.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
removeAt(getAdapterPosition());
}
});
}
}
public void removeAt(int position) {
bookings.remove(position);
notifyItemRemoved(position);
notifyItemRangeChanged(position, bookings.size());
DBHelper.delete(position);
}
}
DBHelper.java
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
public class DBHelper extends SQLiteOpenHelper {
public static final int DATABASE_VERSION = 1;
public static final String DATABASE_NAME = "bookingsDb";
public static final String TABLE_BOOKINGS = "bookings";
public static final String KEY_ID = "_id";
public static final String KEY_NUMBER = "_numbers";
public static final String KEY_NAME = "_names";
public static final String KEY_HOURS = "_hours";
public static final String KEY_MINUTES = "_minutes";
public static final String KEY_PHONE= "_phones";
Context myContext;
static DBHelper dbHelper;
static SQLiteDatabase database;
public DBHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
myContext = context;
}
#Override
public void onCreate(SQLiteDatabase db) {
db.execSQL("create table " + TABLE_BOOKINGS + "("
+ KEY_ID + " integer primary key,"
+ KEY_NUMBER + " integer,"
+ KEY_NAME + " text,"
+ KEY_HOURS + " text,"
+ KEY_MINUTES + " text,"
+ KEY_PHONE + " text" + ")");
dbHelper = new DBHelper(myContext);
}
#Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL("drop table if exists " + TABLE_BOOKINGS);
onCreate(db);
}
public static void delete(int id){
database = dbHelper.getWritableDatabase();
database.delete(TABLE_BOOKINGS, KEY_ID + "=" + id, null);
}
}
And my TableActivity.java if needed
import android.content.Context;
import android.content.Intent;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;
import java.util.ArrayList;
import java.util.List;
public class TableActivity extends AppCompatActivity {
int currentTable;
Button createNewBooking;
List<Booking> bookings;
TextView name;
TextView time;
DataAdapter adapter;
RecyclerView recyclerView;
DBHelper dbHelper;
View.OnClickListener createNewBookingListener = new View.OnClickListener() {
#Override
public void onClick(View v) {
Intent intent = new Intent(TableActivity.this, BookingActivity.class);
startActivity(intent);
}
};
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_table);
currentTable = MainActivity.getCurrentTable();
createNewBooking = findViewById(R.id.createNewBooking);
createNewBooking.setOnClickListener(createNewBookingListener);
bookings = new ArrayList<>();
dbHelper = new DBHelper(this);
setInitialData();
recyclerView = findViewById(R.id.list);
recyclerView.setHasFixedSize(true);
LinearLayoutManager linearLayoutManager = new LinearLayoutManager(this);
recyclerView.setLayoutManager(linearLayoutManager);
adapter = new DataAdapter(this, bookings);
recyclerView.setAdapter(adapter);
}
private void setInitialData() {
SQLiteDatabase database = dbHelper.getWritableDatabase();
Cursor cursor = database.query(DBHelper.TABLE_BOOKINGS, null, null, null, null, null, null);
if (cursor.moveToFirst()) {
int nameIndex = cursor.getColumnIndex(DBHelper.KEY_NAME);
int hoursIndex = cursor.getColumnIndex(DBHelper.KEY_HOURS);
int minutesIndex = cursor.getColumnIndex(DBHelper.KEY_MINUTES);
int phoneIndex = cursor.getColumnIndex(DBHelper.KEY_PHONE);
do {
bookings.add(new Booking(
currentTable,
cursor.getString(nameIndex),
cursor.getString(hoursIndex),
cursor.getString(minutesIndex),
cursor.getString(phoneIndex)
));
} while (cursor.moveToNext());
} else {
Toast.makeText(this, "Броней нет", Toast.LENGTH_SHORT).show();
}
cursor.close();
dbHelper.close();
}
}
Any ideas, please?

you are giving position for delete, it's not necessary to id will be same as per adapter position.
try this :
crossImage.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Booking booking = bookings.get(getAdapterPosition());
datatype id = booking.getId();
removeAt(getAdapterPosition(),id);
}
});
public void removeAt(int position, dataType id) {
bookings.remove(position);
notifyItemRemoved(position);
notifyItemRangeChanged(position, bookings.size());
DBHelper.delete(id);
}

NPE with custom adapter

I am making a custom adapter for list view and got NPE. I have already read other questions but none of them.
Here is the logcat
07-04 06:54:58.036: E/AndroidRuntime(1340): FATAL EXCEPTION: main
07-04 06:54:58.036: E/AndroidRuntime(1340): java.lang.NullPointerException
07-04 06:54:58.036: E/AndroidRuntime(1340): at com.example.amirkh.MainActivity$FastFoodAdapter.getView(MainActivity.java:166)
07-04 06:54:58.036: E/AndroidRuntime(1340): at android.widget.AbsListView.obtainView(AbsListView.java:2159)
07-04 06:54:58.036: E/AndroidRuntime(1340): at android.widget.ListView.measureHeightOfChildren(ListView.java:1246)
07-04 06:54:58.036: E/AndroidRuntime(1340): at android.widget.ListView.onMeasure(ListView.java:1158)
07-04 06:54:58.036: E/AndroidRuntime(1340): at android.view.View.measure(View.java:15518)
07-04 06:54:58.036: E/AndroidRuntime(1340): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4825)
07-04 06:54:58.036: E/AndroidRuntime(1340): at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1404)
07-04 06:54:58.036: E/AndroidRuntime(1340): at android.widget.TableRow.measureChildBeforeLayout(TableRow.java:247)
the code works this way. there is a databasehandler that organize database, a fastfood class and main class. in main class the user enteres a fastfood name and it goes to data base. when user clicks on the"show data" tab whole data should be shown.
here is the main class:
package com.example.amirkh;
import java.util.ArrayList;
import java.util.List;
import android.R.integer;
import android.R.menu;
import android.os.Bundle;
import android.app.Activity;
import android.app.TabActivity;
import android.content.Context;
import android.content.Intent;
import android.graphics.drawable.Drawable;
import android.view.ActionProvider;
import android.view.ContextMenu;
import android.view.Gravity;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.SubMenu;
import android.view.View;
import android.view.ViewGroup;
import android.view.ContextMenu.ContextMenuInfo;
import android.view.MenuItem.OnActionExpandListener;
import android.view.MenuItem.OnMenuItemClickListener;
import android.view.View.OnClickListener;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ExpandableListView;
import android.widget.ImageView;
import android.widget.ListView;
import android.widget.RadioButton;
import android.widget.RadioGroup;
import android.widget.TabHost;
import android.widget.TextView;
import android.widget.Toast;
public class MainActivity extends TabActivity {
private TabHost myTabHost;
private FastFoodAdapter<String> adpter;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
myTabHost = getTabHost();
TabHost.TabSpec spec;
// Adding First Tab
spec = myTabHost.newTabSpec("first");
spec.setContent(R.id.inputtab);
spec.setIndicator("Input data");
myTabHost.addTab(spec);
// Adding Second Tab
spec = myTabHost.newTabSpec("second");
spec.setContent(R.id.listView1);
spec.setIndicator("Show data");
myTabHost.addTab(spec);
myTabHost.setCurrentTab(0);
// final List<FastFood> fflist = new ArrayList<FastFood>();
final EditText etname = (EditText) findViewById(R.id.etname);
final EditText etaddress = (EditText) findViewById(R.id.etaddress);
final ListView lv = (ListView) findViewById(R.id.listView1);
final DataBaseHandeler dbh = new DataBaseHandeler(MainActivity.this);
final RadioGroup radiogroup = (RadioGroup) findViewById(R.id.radioGroup1);
final FastFood fastfood = new FastFood();
final RadioButton rbsit = (RadioButton) findViewById(R.id.rbsit);
final RadioButton rbdeli = (RadioButton) findViewById(R.id.rbdeliv);
final RadioButton rbtake = (RadioButton) findViewById(R.id.rbtake);
refreshComponents();
Button save = (Button) findViewById(R.id.btnsave);
Button remove = (Button) findViewById(R.id.btnremove);
// Create context menu
registerForContextMenu(lv);
// end of context menu
// start of save button
save.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View arg0) {
FastFood ffastfood = new FastFood("", "", "");
ffastfood.setName(etname.getText().toString());
ffastfood.setAddress(etaddress.getText().toString());
etname.setText("");
etaddress.setText("");
if (rbsit.isChecked()) {
ffastfood.setFlag("1");
} else if (rbtake.isChecked()) {
ffastfood.setFlag("2");
} else if (rbdeli.isChecked()) {
ffastfood.setFlag("3");
}
Toast toast = Toast.makeText(MainActivity.this,
"Fastfood is saved.", 2000);
toast.setGravity(Gravity.CENTER, 0, 0);
toast.show();
dbh.addFastFood(ffastfood);
refreshComponents();
}
}); // end of save
// remove
remove.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View arg0) {
EditText etrmvid = (EditText) findViewById(R.id.etrmvid);
dbh.removeFastFood(Integer.parseInt(etrmvid.getText()
.toString()));
etrmvid.setText("");
Toast toast = Toast.makeText(MainActivity.this,
"Fastfood is removed.", 2000);
toast.setGravity(Gravity.CENTER, 0, 0);
toast.show();
refreshComponents();
}
});// end of remove
Context context = getApplicationContext();
// Adapter
}
class FastFoodAdapter<String> extends ArrayAdapter<String> {
public FastFood fastfood = new FastFood();
public FastFoodAdapter(Context context, int textViewResourceId,
List objects) {
super(context, textViewResourceId, objects);
// TODO Auto-generated constructor stub
}
#Override
public View getView(int position, View convertView, ViewGroup parent) {
// TODO Auto-generated method stub
if (convertView == null)
{
LayoutInflater inflater = (LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE);
View row = inflater.inflate(R.layout.listview_item_row, parent,
false);
}
LayoutInflater inflater = (LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE);
View row = inflater.inflate(R.layout.listview_item_row, parent,
false);
TextView tv = (TextView) row.findViewById(R.id.txtTitle23);
TextView tv2 = (TextView) row.findViewById(R.id.txtTitle2);
ImageView iv = (ImageView) row.findViewById(R.id.imgIcon);
tv.setText(fastfood.getName());
tv2.setText(fastfood.getAddress());
if (fastfood.getFlag().equals("1"))
iv.setImageResource(R.drawable.sit);
else if (fastfood.getFlag().equals("2"))
iv.setImageResource(R.drawable.ta);
else if (fastfood.getFlag().equals("3"))
iv.setImageResource(R.drawable.deli);
return row;
}
}// /end of adapter
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
public void onCreateContextMenu(ContextMenu menu, View v,
ContextMenuInfo menuInfo) {
getMenuInflater().inflate(R.menu.contexmenu, menu);
super.onCreateContextMenu(menu, v, menuInfo);
}
#Override
public boolean onContextItemSelected(MenuItem item) {
return super.onContextItemSelected(item);
}
private void refreshComponents() {
ListView lv = (ListView) findViewById(R.id.listView1);
TextView lblCount = (TextView) findViewById(R.id.lblcount);
DataBaseHandeler dbh = new DataBaseHandeler(MainActivity.this);
List<FastFood> fflist = dbh.getAllFastFoods();
// lv.setAdapter(new FastFoodAdapter<String>(context,
// textViewResourceId, objects))
lv.setAdapter(new FastFoodAdapter<FastFood>(MainActivity.this,
android.R.layout.simple_list_item_1, fflist));
lblCount.setText("Count of all FastFoods are " + dbh.getFastFoodCount());
}
}
here is fastfood class
package com.example.amirkh;
public class FastFood {
private String name;
private String address;
private String flag;
private int id;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getFlag() {
return flag;
}
public void setFlag(String flag) {
this.flag = flag;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getAddress() {
return address;
}
public void setAddress(String address) {
this.address = address;
}
public FastFood(String name, String address, String phone) {
super();
this.name = name;
this.address = address;
}
public FastFood() {
// TODO Auto-generated constructor stub
}
#Override
public String toString() {
return (String.format("%s %s ", getName(), getAddress()));
}
}
and the databasehandeler
package com.example.amirkh;
import java.util.ArrayList;
import java.util.List;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteDatabase.CursorFactory;
import android.database.sqlite.SQLiteOpenHelper;
public class DataBaseHandeler extends SQLiteOpenHelper {
private static final int DATABASE_VERSION = 1;
private static final String DATABASE_NAME = "FastFoodManager";
private static final String TABALE_FASTFOODS = "fastfoods";
private static final String KEY_ID = "_id";
private static final String KEY_NAME = "name";
private static final String KEY_ADDRESS = "address";
private static final String KEY_FLAG = "flag";
public DataBaseHandeler(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
// TODO Auto-generated constructor stub
}
#Override
public void onCreate(SQLiteDatabase db) {
db.execSQL("CREATE TABLE IF NOT EXISTS " + TABALE_FASTFOODS + " ("
+ KEY_ID + " INTEGER PRIMARY KEY, " + KEY_NAME + " TEXT, "
+ KEY_ADDRESS + " TEXT, " + KEY_FLAG + " TEXT);");
}
#Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// TODO Auto-generated method stub
db.execSQL("DROP TABLE IF EXISTS " + TABALE_FASTFOODS);
onCreate(db);
}
// insert a record
public void addFastFood(FastFood fastfood) {
SQLiteDatabase db = this.getWritableDatabase();
ContentValues values = new ContentValues();
values.put(KEY_NAME, fastfood.getName());
values.put(KEY_ADDRESS, fastfood.getAddress());
values.put(KEY_FLAG, fastfood.getFlag());
db.insert(TABALE_FASTFOODS, null, values);
db.close();
}
// remove a record by ID
public void removeFastFood(int id) {
SQLiteDatabase db = this.getWritableDatabase();
db.delete(TABALE_FASTFOODS, KEY_ID + " =?",
new String[] { String.valueOf(id) });
db.close();
}
// count
public int getFastFoodCount() {
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor = db.rawQuery("SELECT * FROM " + TABALE_FASTFOODS, null);
// db.close();
return cursor.getCount();
}
// get all contacts
public List<FastFood> getAllFastFoods() {
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor = db.rawQuery("SELECT * FROM " + TABALE_FASTFOODS, null);
List<FastFood> fflist = new ArrayList<FastFood>();
if (cursor.moveToFirst()) {
do {
FastFood ff = new FastFood();
ff.setId(Integer.parseInt(cursor.getString(0)));
ff.setName(cursor.getString(1));
ff.setAddress(cursor.getString(2));
ff.setFlag(cursor.getString(3));
fflist.add(ff);
} while (cursor.moveToNext());
}
// db.close();
return fflist;
}
}
Thanks for helping

You are getting this NullPointerException because you are trying to compare a null String in this line
fastfood.getFlag().equals("1")
In your adapter you create an object of Food using
public FastFood fastfood = new FastFood();
In the empty constructor of Food class nothing is assigned to any of the member String so when you try to do
fastfood.getFlag().equals("1")
you are trying to call equals method on a null object.
So you get a NullPointerException.
You should use the Food objects from the List that you pass in the FastFoodAdapter constructor.

Your NPE come from:
if (fastfood.getFlag().equals("1"))
So fastfood.getFlag() seems null. You should use setFlag() before or try this comparison:
if ("1".equals(fastfood.getFlag()))