i have searched all over but no answer is working in my case, i am developing an app where i need to have a database, an activity that imports a csv file into that database and displays it in a ListView, and another activity that onClick of a button runs a cursor on the values of one column in that database and compares it to a string and as a result returns a toast that says a match has been found. I have a DBController class that extends SQLiteOpenHelper and i call this class in the other activities, it connects perfectly well in the first activity, it imports the csv file and displays it in the listview, but in the second activity its not doing anything, i don't know if the problem is that its not connecting or whether it's returning an empty table.
Here is my code:
DBController class:
package org.opencv.javacv.facerecognition;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;
import java.util.ArrayList;
import java.util.HashMap;
public class DBController extends SQLiteOpenHelper {
private static final String LOGCAT = null;
public DBController(Context applicationcontext) {
super(applicationcontext, "classes.db", null, 1); // creating DATABASE
Log.d(LOGCAT, "Created");
}
@Override
public void onCreate(SQLiteDatabase database) {
String query;
query = "CREATE TABLE IF NOT EXISTS course1 ( Id INTEGER PRIMARY KEY, student_number TEXT UNIQUE, student_fn TEXT, student_ln TEXT, attended INTEGER DEFAULT 0, time_attended TEXT)";
database.execSQL(query);
}
@Override
public void onUpgrade(SQLiteDatabase database, int version_old,
int current_version) {
String query;
query = "DROP TABLE IF EXISTS course1";
database.execSQL(query);
onCreate(database);
}
public ArrayList<HashMap<String, String>> getAllProducts() {
ArrayList<HashMap<String, String>> studentList;
studentList = new ArrayList<HashMap<String, String>>();
String selectQuery = "SELECT * FROM course1";
SQLiteDatabase database = this.getWritableDatabase();
Cursor cursor = database.rawQuery(selectQuery, null);
if (cursor.moveToFirst()) {
do {
//Id, Company,Name,Price
HashMap<String, String> map = new HashMap<String, String>();
map.put("Id", cursor.getString(0));
map.put("student_number", cursor.getString(1));
map.put("student_fn", cursor.getString(2));
map.put("student_ln", cursor.getString(3));
map.put("attended", cursor.getString(4));
map.put("time_attended", cursor.getString(5));
studentList.add(map);
} while (cursor.moveToNext());
}
return studentList;
}
}
DBActivity which imports csv file and displays it in listview:
package org.opencv.javacv.facerecognition;
import android.app.Dialog;
import android.app.ListActivity;
import android.content.ActivityNotFoundException;
import android.content.ContentValues;
import android.content.Context;
import android.content.Intent;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import android.widget.TextView;
import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.util.ArrayList;
import java.util.HashMap;
public class DBActivity extends ListActivity {
TextView lbl;
DBController controller = new DBController(this);
Button btnimport;
ListView lv;
final Context context = this;
ListAdapter adapter;
ArrayList<HashMap<String, String>> myList;
public static final int requestcode = 1;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.database_view);
lbl = (TextView) findViewById(R.id.txtresulttext);
btnimport = (Button) findViewById(R.id.btnupload);
lv = getListView();
btnimport.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent fileintent = new Intent(Intent.ACTION_GET_CONTENT);
fileintent.setType("gagt/sdf");
try {
startActivityForResult(fileintent, requestcode);
} catch (ActivityNotFoundException e) {
lbl.setText("No activity can handle picking a file. Showing alternatives.");
}
}
});
myList= controller.getAllProducts();
if (myList.size() != 0) {
ListView lv = getListView();
ListAdapter adapter = new SimpleAdapter(DBActivity.this, myList,
R.layout.v, new String[]{"student_number", "student_fn", "student_ln" , "attended" , "time_attended"}, new int[]{
R.id.studentnumber, R.id.studentfn, R.id.studentln, R.id.attended, R.id.timeattended});
setListAdapter(adapter);
lbl.setText("");
}
}
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
if (data == null)
return;
switch (requestCode) {
case requestcode:
String filepath = data.getData().getPath();
controller = new DBController(getApplicationContext());
SQLiteDatabase db = controller.getWritableDatabase();
String tableName = "course1";
db.execSQL("delete from " + tableName);
try {
if (resultCode == RESULT_OK) {
try {
FileReader file = new FileReader(filepath);
BufferedReader buffer = new BufferedReader(file);
ContentValues contentValues = new ContentValues();
String line = "";
db.beginTransactionNonExclusive();
while ((line = buffer.readLine()) != null) {
String[] str = line.split(",", 5); // defining 3 columns with null or blank field //values acceptance
//Id, Company,Name,Price
String student_number = str[0].toString();
String student_fn = str[1].toString();
String student_ln = str[2].toString();
String attended = str[3].toString();
String time_attended = str[4].toString();
contentValues.put("student_number", student_number);
contentValues.put("student_fn", student_fn);
contentValues.put("student_ln", student_ln);
contentValues.put("attended", attended);
contentValues.put("time_attended", time_attended);
db.insert(tableName, null, contentValues);
lbl.setText("Successfully Updated Database.");
}
db.setTransactionSuccessful();
db.endTransaction();
} catch (IOException e) {
if (db.inTransaction())
db.endTransaction();
Dialog d = new Dialog(this);
d.setTitle(e.getMessage().toString() + "first");
d.show();
// db.endTransaction();
}
} else {
if (db.inTransaction())
db.endTransaction();
Dialog d = new Dialog(this);
d.setTitle("Only CSV files allowed");
d.show();
}
} catch (Exception ex) {
if (db.inTransaction())
db.endTransaction();
Dialog d = new Dialog(this);
d.setTitle(ex.getMessage().toString() + "second");
d.show();
// db.endTransaction();
}
db.close();
}
myList= controller.getAllProducts();
if (myList.size() != 0) {
ListView lv = getListView();
ListAdapter adapter = new SimpleAdapter(DBActivity.this, myList,
R.layout.v, new String[]{"student_number", "student_fn", "student_ln" , "attended" , "time_attended"}, new int[]{
R.id.studentnumber, R.id.studentfn, R.id.studentln, R.id.attended, R.id.timeattended});
setListAdapter(adapter);
lbl.setText("Data Imported");
}
}
}
And here is how im comparing a string to a column in the table in the second class (this is just a part of the activity): first i added this at the top:
DBController controller = new DBController(this);
and here is the onClick code in the onCreate method:
buttonSearch.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
controller = new DBController(getApplicationContext());
SQLiteDatabase db = controller.getWritableDatabase();
String query = "SELECT * FROM course1 WHERE student_number=" + number;
Cursor cursor = db.rawQuery(query, null);
if(cursor.getCount() > 0) {
cursor.moveToFirst();
while(!cursor.isAfterLast()) {
Toast.makeText(getApplicationContext(), "match found!", Toast.LENGTH_LONG).show();
cursor.moveToNext();
}
}
}
});
I just can't figure out what the problem might be.. I'm rather new in android so any help will be highly appreciated.
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