android studio retrieve data from Sqlite database and display it into textview

Question

Hi guys please I need your help. I create SQLite Database in my app and I insert the data into it. And now I want to retrieve data from it but I want just insert one data an

Answer 1

Here is an example of how I achieved this.

In this example I will store, retrieve, update and delete a students name and age.

---

First create a class, I called mine

DBManager.java

public class DBManager {
    private Context context;
    private SQLiteDatabase database;
    private SQLiteHelper dbHelper;

    public DBManager(Context c) {
        this.context = c;
    }

    public DBManager open() throws SQLException {
        this.dbHelper = new SQLiteHelper(this.context);
        this.database = this.dbHelper.getWritableDatabase();
        return this;
    }

    public void close() {
        this.dbHelper.close();
    }

    public void insert(String name, String desc) {
        ContentValues contentValue = new ContentValues();
        contentValue.put(SQLiteHelper.NAME, name);
        contentValue.put(SQLiteHelper.AGE, desc);
        this.database.insert(SQLiteHelper.TABLE_NAME_STUDENT, null, contentValue);
    }


    public Cursor fetch() {
        Cursor cursor = this.database.query(SQLiteHelper.TABLE_NAME_STUDENT, new String[]{SQLiteHelper._ID, SQLiteHelper.NAME, SQLiteHelper.AGE}, null, null, null, null, null);
        if (cursor != null) {
            cursor.moveToFirst();
        }
        return cursor;
    }

    public int update(long _id, String name, String desc) {
        ContentValues contentValues = new ContentValues();
        contentValues.put(SQLiteHelper.NAME, name);
        contentValues.put(SQLiteHelper.AGE, desc);
        return this.database.update(SQLiteHelper.TABLE_NAME_STUDENT, contentValues, "_id = " + _id, null);
    }

    public void delete(long _id) {
        this.database.delete(SQLiteHelper.TABLE_NAME_STUDENT, "_id=" + _id, null);
    }
}

Then create a SQLiteOpenHelper I called mine

SQLiteHelper.java

public class SQLiteHelper extends SQLiteOpenHelper {
    public static final String AGE = "age";
    private static final String CREATE_TABLE_STUDENT = " create table STUDENTS ( _id INTEGER PRIMARY KEY AUTOINCREMENT, name TEXT NOT NULL , age TEXT );";
    private static final String DB_NAME = "STUDENTS.DB";
    private static final int DB_VERSION = 1;
    public static final String NAME = "name";
    public static final String TABLE_NAME_STUDENT = "STUDENTS";
    public static final String _ID = "_id";

    public SQLiteHelper(Context context) {
        super(context, DB_NAME, null, 1);
    }

    public void onCreate(SQLiteDatabase db) {
        db.execSQL(CREATE_TABLE_STUDENT);
    }

    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        db.execSQL("DROP TABLE IF EXISTS STUDENTS");
        onCreate(db);
    }   
}

---

TO ADD:

In this example I take the text from EditText and when the button is clicked I check if the EditText is empty or not. If it is not empty and the student doesn't already exist I insert the students name and age into the database. I display a Toast, letting the user know of the status:

btnAdd.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View view) {
        if (edtName.getText().toString().trim().length() == 0) {
            Toast.makeText(getApplicationContext(), "Please provide your students name", Toast.LENGTH_SHORT).show();
        } else{
            try {
                if (edtAge.getText().toString().trim().length() != 0) {
                    String name = edtName.getText().toString().trim();
                    String age = edtAge.getText().toString().trim();
                    String query = "Select * From STUDENTS where name = '"+name+"'";
                    if(dbManager.fetch().getCount()>0){
                        Toast.makeText(getApplicationContext(), "Already Exist!", Toast.LENGTH_SHORT).show();
                    }else{
                        dbManager.insert(name, age);
                        Toast.makeText(getApplicationContext(), "Added successfully!", Toast.LENGTH_SHORT).show();                           
                    }

                } else {
                    Toast.makeText(getApplicationContext(), "please provide student age!", Toast.LENGTH_SHORT).show();                           
                }
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }  
});

---

TO UPDATE:

Here I take the Text in EditText and update the student when the button is clicked. You can also place the following in a try/catch to make sure it is updated successfully.

btnupdate.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View view) {
        String name = nameText.getText().toString();
        String age = ageText.getText().toString();
        dbManager.update(_id, name, age);
        Toast.makeText(getApplicationContext(), "Updated successfully!", Toast.LENGTH_SHORT).show();
    }
});

---

TO DELETE:

dbManager.delete(_id);
Toast.makeText(getApplicationContext(), "Deleted successfully!", Toast.LENGTH_SHORT).show();

---

TO GET:

Here I get the name of the student and display it in a TextView

DBManager dbManager = new DBManager(getActivity());
dbManager.open();

Cursor cursor = dbManager.fetch();
cursor.moveToFirst();
final TextView studentName = (TextView) getActivity().findViewById(R.id.nameOfStudent);
studentName.settext(cursor.getString(0));