I am new to android and tried to use open source project. The projects database is sqlite database. When I run project and checked, I saw there is no data in my android device monitor. Please someone check my codes if there are mistakes?
package com.andisofttechnology.myapplication;
import android.app.Activity;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.util.Log;
import android.widget.Toast;
public class databaseHandler {
SQLiteDatabase database;
Activity activity;
public databaseHandler(Activity activity) {
this.activity = activity;
database = activity.openOrCreateDatabase("ASSIST", activity.MODE_PRIVATE, null);
createTable();
}
public void createTable()
{
try {
String qu = "CREATE TABLE IF NOT EXISTS STUDENT(name varchar(1000)," +
"cl varchar(100), " +
"regno varchar(100) primary key, contact varchar(100),roll integer);";
database.execSQL(qu);
}catch (Exception e)
{
Toast.makeText(activity,"Error Occured for create table",Toast.LENGTH_LONG).show();
}
try {
String qu = "CREATE TABLE IF NOT EXISTS ATTENDANCE(datex date," +
"hour int, " +
"register varchar(100) ,isPresent boolean);";
database.execSQL(qu);
}catch (Exception e)
{
Toast.makeText(activity,"Error Occured for create table",Toast.LENGTH_LONG).show();
}
try {
String qu = "CREATE TABLE IF NOT EXISTS NOTES(title varchar(100) not null," +
"body varchar(10000), cls varchar(1000), sub varchar(1000) ,datex TIMESTAMP default CURRENT_TIMESTAMP);";
database.execSQL(qu);
}catch (Exception e)
{
Toast.makeText(activity,"Error Occured for create table",Toast.LENGTH_LONG).show();
}
try {
String qu = "CREATE TABLE IF NOT EXISTS SCHEDULE(cl varchar(100),subject varchar(1000)," +
"timex time, day_week varchar(100));";
database.execSQL(qu);
}catch (Exception e)
{
Toast.makeText(activity,"Error Occured for create table",Toast.LENGTH_LONG).show();
}
}
public boolean execAction(String qu)
{
Log.i("databaseHandler", qu);
try {
database.execSQL(qu);
}catch (Exception e)
{
Log.e("databaseHandler", qu);
Toast.makeText(activity,"Error Occured for execAction",Toast.LENGTH_LONG).show();
return false;
}
return true;
}
Cursor execQuery(String qu)
{
try {
return database.rawQuery(qu,null);
}catch (Exception e)
{
Log.e("databaseHandler", qu);
// Toast.makeText(activity,"Error Occured for execAction",Toast.LENGTH_LONG).show();
}
return null;
}
}
Student_registration.class
package com.andisofttechnology.myapplication;
import android.app.Activity;
import android.app.AlertDialog;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ImageView;
import android.widget.Spinner;
import android.widget.Toast;
/*import java.util.ArrayList;*/
public class Student_Registartion extends AppCompatActivity {
private EditText name,register,contact;
Activity activity = this;
Spinner spinner;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_student__registartion);
spinner = (Spinner) findViewById(R.id.spinner);
/* ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, android.R.layout.simple_spinner_dropdown_item, AppBase.divisions);
spinner.setAdapter(adapter);*/
Button btn = (Button) findViewById(R.id.btnSave);
assert btn != null;
btn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
saveToDatabase(v);
}
});
}
public void saveToDatabase(View view) {
EditText name = (EditText)findViewById(R.id.name);
EditText roll = (EditText)findViewById(R.id.roll);
EditText register = (EditText)findViewById(R.id.register);
EditText contact = (EditText)findViewById(R.id.contact);
String classSelected = spinner.getSelectedItem().toString();
if(name.getText().length()<2||roll.getText().length()==0||register.getText().length()<2||
contact.getText().length()<2||classSelected.length()<2)
{
AlertDialog.Builder alert = new AlertDialog.Builder(activity);
alert.setTitle("Invalid");
alert.setMessage("Insufficient Data");
alert.setPositiveButton("OK", null);
alert.show();
return;
}
String qu = "INSERT INTO STUDENT VALUES('" +name.getText().toString()+ "'," +
"'" + classSelected +"',"+
"'" + register.getText().toString().toUpperCase() +"',"+
"'" + contact.getText().toString() +"',"+
"" + Integer.parseInt(roll.getText().toString()) +");";
Log.d("Student Reg" , qu);
AppBase.handler.execAction(qu);
qu = "SELECT * FROM STUDENT WHERE regno = '" + register.getText().toString() + "';";
Log.d("Student Reg" , qu);
if(AppBase.handler.execQuery(qu)!=null)
{
Toast.makeText(getBaseContext(),"Student Added", Toast.LENGTH_LONG).show();
this.finish();
}
}
}
......................................................................
Log Cat
E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.andisofttechnology.myapplication, PID: 32163
java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String java.lang.Object.toString()' on a null object reference
at com.andisofttechnology.myapplication.Student_Registartion.saveToDatabase(Student_Registartion.java:48)
at com.andisofttechnology.myapplication.Student_Registartion$1.onClick(Student_Registartion.java:37)
at android.view.View.performClick(View.java:6294)
at android.view.View$PerformClick.run(View.java:24770)
at android.os.Handler.handleCallback(Handler.java:790)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:164)
at android.app.ActivityThread.main(ActivityThread.java:6494)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:807)
