iem following a tutorial on youtube about using SQLite in android and the code crashes the app on start code
MainActivity.java
package com.example.asd;
import android.app.Activity;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
public class MainActivity extends Activity {
VivzHelper vivzHelper;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
vivzHelper = new VivzHelper(this);
SQLiteDatabase sqLiteDatabase = vivzHelper.getWritableDatabase();
}
@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;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
}
Message.java
package com.example.asd;
import android.content.Context;
import android.widget.Toast;
public class Message {
public static void message(Context context, String message) {
Toast.makeText(context, message, Toast.LENGTH_LONG).show();
}
}
VivzHelper.java
package com.example.asd;
import android.content.Context;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
public class VivzHelper extends SQLiteOpenHelper {
private static final String DATABASE_NAME = "vivzdatabase";
private static final String TABLE_NAME = "VIVZTABLE";
private static final int DATABASE_VERSION = 1;
private static final String UID = "_id";
private static final String NAME = "Name";
private static final String CREATE_TABLE = "CREATE TABLE " + TABLE_NAME + " (" + UID
+ " INTEGER PRIMARY KEY AUTOINCREMENT, " + NAME + " VARCHAR(255));";
private static final String DROP_TABLE = "DROP TABLE IF EXISTS" + TABLE_NAME;
private Context context;
public VivzHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
Message.message(context, "constructor called");
}
@Override
public void onCreate(SQLiteDatabase db) {
try {
db.execSQL(CREATE_TABLE);
Message.message(context, "onCreate called");
} catch (SQLException e) {
Message.message(context, "" + e);
}
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
try {
Message.message(context, "onUpgrade called");
db.execSQL(DROP_TABLE);
onCreate(db);
} catch (SQLException e) {
Message.message(context, "" + e);
}
}
}
The app crashes on
SQLiteDatabase sqLiteDatabase = vivzHelper.getWritableDatabase();
error log
12-11 19:49:16.459: E/AndroidRuntime(6043): FATAL EXCEPTION: main
12-11 19:49:16.459: E/AndroidRuntime(6043): Process: com.example.asd, PID: 6043
12-11 19:49:16.459: E/AndroidRuntime(6043): java.lang.RuntimeException: Unable to start activity ComponentInfo{http://ift.tt/1hzVPG3}: java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.res.Resources android.content.Context.getResources()' on a null object reference
12-11 19:49:16.459: E/AndroidRuntime(6043): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2695)
12-11 19:49:16.459: E/AndroidRuntime(6043): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2769)
12-11 19:49:16.459: E/AndroidRuntime(6043): at android.app.ActivityThread.access$900(ActivityThread.java:177)
12-11 19:49:16.459: E/AndroidRuntime(6043): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1430)
12-11 19:49:16.459: E/AndroidRuntime(6043): at android.os.Handler.dispatchMessage(Handler.java:102)
12-11 19:49:16.459: E/AndroidRuntime(6043): at android.os.Looper.loop(Looper.java:135)
12-11 19:49:16.459: E/AndroidRuntime(6043): at android.app.ActivityThread.main(ActivityThread.java:5910)
12-11 19:49:16.459: E/AndroidRuntime(6043): at java.lang.reflect.Method.invoke(Native Method)
12-11 19:49:16.459: E/AndroidRuntime(6043): at java.lang.reflect.Method.invoke(Method.java:372)
12-11 19:49:16.459: E/AndroidRuntime(6043): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1405)
12-11 19:49:16.459: E/AndroidRuntime(6043): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1200)
12-11 19:49:16.459: E/AndroidRuntime(6043): Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.res.Resources android.content.Context.getResources()' on a null object reference
12-11 19:49:16.459: E/AndroidRuntime(6043): at android.widget.Toast.<init>(Toast.java:130)
12-11 19:49:16.459: E/AndroidRuntime(6043): at android.widget.Toast.makeText(Toast.java:427)
12-11 19:49:16.459: E/AndroidRuntime(6043): at com.example.asd.Message.message(Message.java:9)
12-11 19:49:16.459: E/AndroidRuntime(6043): at com.example.asd.VivzHelper.onCreate(VivzHelper.java:29)
12-11 19:49:16.459: E/AndroidRuntime(6043): at android.database.sqlite.SQLiteOpenHelper.getDatabaseLocked(SQLiteOpenHelper.java:251)
12-11 19:49:16.459: E/AndroidRuntime(6043): at android.database.sqlite.SQLiteOpenHelper.getWritableDatabase(SQLiteOpenHelper.java:163)
12-11 19:49:16.459: E/AndroidRuntime(6043): at com.example.asd.MainActivity.onCreate(MainActivity.java:18)
12-11 19:49:16.459: E/AndroidRuntime(6043): at android.app.Activity.performCreate(Activity.java:6178)
12-11 19:49:16.459: E/AndroidRuntime(6043): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1118)
12-11 19:49:16.459: E/AndroidRuntime(6043): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2648)
12-11 19:49:16.459: E/AndroidRuntime(6043): ... 10 more
I do not know whats wrong with the code it looks exactly the same as in video ???
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