App stops when trying to add information in it

Question

When I try to add information in database the app stops. This is the class where I store my information about an item(i have 3 columns in database):

public class Elevator extends AppCompatActivity {
public int id ;
public String name;
public Date date;

//getters and setters here

public Elevator(int id, String name, Date date){
    setId(id);
    setName(name);
    setDate(date);
    DatabaseHelper myDB = new DatabaseHelper(this);
    myDB.addData(id,name,date);
}
}

And my main activity with the Button on which I have clickListener:

public class MainActivity extends AppCompatActivity {

DatabaseHelper myDB;
Button btnAdd;
EditText editText;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    btnAdd = (Button) findViewById(R.id.btnAdd);
    editText = (EditText) findViewById(R.id.editText);
    myDB = new DatabaseHelper(this);

    btnAdd.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
           String newEntry =  editText.getText().toString();
           int id =  myDB.getLastID();
            if (id == -1) {
                id=1;
                new  Elevator(id,newEntry,null);
            } else{
                new Elevator(id,newEntry,null);
            }
        }
    });
}
}

Is it right to add information in database in the constructor as I did or I should do it in other way? And should my Elevator class extend AppCompatActivity, if it does not i cant use instance of my DatabaseHelperClass.

This is the logcat:

07-24 11:51:55.141: E/AndroidRuntime(5251): FATAL EXCEPTION: main
E/AndroidRuntime(5251): Process: com.example.goshoy.elevatorapp, PID: 5251
E/AndroidRuntime(5251): java.lang.NullPointerException: Attempt to invoke 
virtual method 'android.database.sqlite.SQLiteDatabase 
android.content.Context.openOrCreateDatabase(java.lang.String, int, 
android.database.sqlite.SQLiteDatabase$CursorFactory, 
android.database.DatabaseErrorHandler)' on a null object reference
E/AndroidRuntime(5251):     at 
android.content.ContextWrapper.openOrCreateDatabase(ContextWrapper.java:269)
E/AndroidRuntime(5251):     at 
android.database.sqlite.SQLiteOpenHelper.getDatabaseLocked
(SQLiteOpenHelper.java:223)
E/AndroidRuntime(5251):     at 
android.database.sqlite.SQLiteOpenHelper.getWritableDatabase
(SQLiteOpenHelper.java:163)
E/AndroidRuntime(5251): at 
com.example.goshoy.elevatorapp.DatabaseHelper.addData
(DatabaseHelper.java:49)
E/AndroidRuntime(5251):     at com.example.goshoy.elevatorapp.Elevator.
<init>(Elevator.java:45)
E/AndroidRuntime(5251):     at 
com.example.goshoy.elevatorapp.MainActivity$1.onClick(MainActivity.java:34)
E/AndroidRuntime(5251):     at 
 android.view.View.performClick(View.java:5198)
E/AndroidRuntime(5251):     at 
 android.view.View$PerformClick.run(View.java:21147)
E/AndroidRuntime(5251):     at 
android.os.Handler.handleCallback(Handler.java:739)
E/AndroidRuntime(5251):     at 
android.os.Handler.dispatchMessage(Handler.java:95)
E/AndroidRuntime(5251):     at android.os.Looper.loop(Looper.java:148)
E/AndroidRuntime(5251):     at 
android.app.ActivityThread.main(ActivityThread.java:5417)
E/AndroidRuntime(5251):     at java.lang.reflect.Method.invoke(Native 
Method)
E/AndroidRuntime(5251):     at 
com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run 
(ZygoteInit.java:726)
E/AndroidRuntime(5251):     at 
com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)

Your Elevator class looks like a model class so it should be separate form your activity and shouldn't extend that. Instead your helper class. so call your database helper form your main activity instead. Also this looks like your createoropendb method is causing null so add that code here and have a relook at that method form your helper class — Kapil G, Jul 24 '17 at 12:17

App stops when trying to add information in it

0 Answers0