Display data from database into text view (Android)

Question

This is my code for database class (DatabaseHelper.java)

public Cursor getAllData(){
        SQLiteDatabase db = this.getWritableDatabase();
        Cursor res = db.rawQuery("select * from "+TABLE_NAME,null);
        return res;
    }

This is another class which is (MainSuggestion.java)

public class MenuSuggestion extends AppCompatActivity {
    DatabaseHelper myDb;
    @Override 
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_menu_suggestion);
<br/>
        Cursor res = myDb.getAllData();
        if (res.moveToFirst()) {             
            TextView bmi = (TextView) findViewById(R.id.textView9);
            TextView kcal = (TextView) findViewById(R.id.textView10);
            bmi.setText(res.getString(3));
            kcal.setText(res.getString(4));
        }
    }
}

Can someone tell me, what's wrong with my code?

Did you check that you actually have records in your cursor? — SuperFrog
– SuperFrog, Commented Oct 15, 2015 at 14:41
are you seeing any error message? post it here. Also do db calls on background threads the simplest one is to use asynctasks. — dsharew
– dsharew, Commented Oct 15, 2015 at 14:41
There is no error message, but when I run it using emulator, the emulator shows "Unfortunately, MnutriHealth has stopped". — MoLab
– MoLab, Commented Oct 15, 2015 at 14:43
Then you need to post the stacktrace, else we don't have any way to help you. — Moonbloom
– Moonbloom, Commented Oct 15, 2015 at 14:43

JoeyJubb · Accepted Answer · 2015-10-15 14:51:17Z

4

The exact reason this isn't working is because "myDb" is null on this line.

 Cursor res = myDb.getAllData();

However, I recommend you Running a Query with a CursorLoader. It might seem overkill, loading stuff from the database on the main thread like you are can lead to ANR errors.

answered Oct 15, 2015 at 14:51

JoeyJubb

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Comments

Lay Leangsros · Accepted Answer · 2015-10-15 14:45:55Z

0

Query data from database, you have to use:

this.getReadableDatabase();

You use getWritableDatabase() when you want to write, update, delete data into/from database.

answered Oct 15, 2015 at 14:45

Lay Leangsros

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6 Comments

dsharew Over a year ago

This is good as a recommendation but it is still possible to read from writable databse, so this could not be the cause for the error.

dsharew Over a year ago

@MoLab why dont you provide what you are asked? post the error if you want a solution.

Lay Leangsros Over a year ago

Is it the main activity? if not, did you add this class in Manifest ?

MoLab Over a year ago

@DegenSharew There is no error but when I run it using emulator, the emulator shows "Unfortunately, MnutriHealth has stopped".

dsharew Over a year ago

@MoLab check the log cat there is always an error logged there when app crashes this way.

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