activity_main.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">
    <EditText android:id="@+id/editTextWord"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentTop="true"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:hint="Word"/>
    <EditText android:id="@+id/editTextDefinition"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@+id/editTextWord"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:hint="Definition"/>
    <Button android:id="@+id/buttonAddUpdate"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Save"
        android:layout_alignParentRight="true"
        android:layout_alignParentTop="true" />
    <ListView android:id="@+id/listView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@+id/et_definition"
        android:layout_alignParentLeft="true"
        android:layout_alignParentBottom="true" />
</LinearLayout>

DictionaryAdapter.java

package com.example.loader;

import android.content.Context;
import android.database.Cursor;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.CursorAdapter;
import android.widget.TextView;

public class DictionaryAdapter extends CursorAdapter {
    public DictionaryAdapter(Context context, Cursor c, int flags) {
        super(context, c, flags);
    }

    @Override
    public View newView(Context context, Cursor cursor, ViewGroup parent) {
        return LayoutInflater.from(context)
                .inflate(android.R.layout.simple_list_item_1, parent, false);
    }

    @Override
    public void bindView(View view, Context context, Cursor cursor) {
        TextView textView = view.findViewById(android.R.id.text1);
        textView.setText(cursor.getString(getCursor().getColumnIndex("word")));
    }
}

DictionaryDatabase.java

package com.example.loader;

import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;

public class DictionaryDatabase extends SQLiteOpenHelper {
    private static final String DATABASE_NAME = "dictionary.db";
    private static final String TABLE_DICTIONARY = "dictionary";

    private static final String FIELD_WORD = "word";
    private static final String FIELD_DEFINITION = "definition";
    private static final int DATABASE_VERSION = 1;

    DictionaryDatabase(Context context) {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL("CREATE TABLE " + TABLE_DICTIONARY +
                "(_id integer PRIMARY KEY," +
                FIELD_WORD + " TEXT, " +
                FIELD_DEFINITION + " TEXT);");
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        //Handle database upgrade as needed
    }

    public void saveRecord(String word, String definition) {
        long id = findWordID(word);
        if (id > 0) {
            updateRecord(id, word, definition);
        } else {
            addRecord(word, definition);
        }
    }

    public long addRecord(String word, String definition) {
        SQLiteDatabase db = getWritableDatabase();

        ContentValues values = new ContentValues();
        values.put(FIELD_WORD, word);
        values.put(FIELD_DEFINITION, definition);
        return db.insert(TABLE_DICTIONARY, null, values);
    }

    public int updateRecord(long id, String word, String definition) {
        SQLiteDatabase db = getWritableDatabase();
        ContentValues values = new ContentValues();
        values.put("_id", id);
        values.put(FIELD_WORD, word);
        values.put(FIELD_DEFINITION, definition);
        return db.update(TABLE_DICTIONARY, values, "_id = ?", new String[]{String.valueOf(id)});
    }
    public int deleteRecord(long id) {
        SQLiteDatabase db = getWritableDatabase();
        return db.delete(TABLE_DICTIONARY, "_id = ?", new String[]{String.valueOf(id)});
    }

    public long findWordID(String word) {
        long returnVal = -1;
        SQLiteDatabase db = getReadableDatabase();
        Cursor cursor = db.rawQuery(
                "SELECT _id FROM " + TABLE_DICTIONARY + " WHERE " + FIELD_WORD + " = ?",
                new String[]{word});
        if (cursor.getCount() == 1) {
            cursor.moveToFirst();
            returnVal = cursor.getInt(0);
        }
        return returnVal;
    }

    public String getDefinition(long id) {
        String returnVal = "";
        SQLiteDatabase db = getReadableDatabase();
        Cursor cursor = db.rawQuery(
                "SELECT definition FROM " + TABLE_DICTIONARY + " WHERE _id = ?",
                new String[]{String.valueOf(id)});
        if (cursor.getCount() == 1) {
            cursor.moveToFirst();
            returnVal = cursor.getString(0);
        }
        return returnVal;
    }

    public Cursor getWordList() {
        SQLiteDatabase db = getReadableDatabase();
        String query = "SELECT _id, " + FIELD_WORD +
                " FROM " + TABLE_DICTIONARY + " ORDER BY " + FIELD_WORD +
                " ASC";
        return db.rawQuery(query, null);
    }
}

DictionaryLoader.java

package com.example.loader;

import android.content.Context;
import android.database.Cursor;

import androidx.loader.content.CursorLoader;

public class DictionaryLoader  extends CursorLoader {
    Context mContext;

    public DictionaryLoader(Context context) {
        super(context);
        mContext = context;
    }

    @Override
    public Cursor loadInBackground() {
        DictionaryDatabase db = new DictionaryDatabase(mContext);
        return db.getWordList();
    }
}

MainActivity.java

package com.example.loader;

import android.database.Cursor;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ListView;
import android.widget.Toast;

import androidx.appcompat.app.AppCompatActivity;
import androidx.loader.app.LoaderManager;
import androidx.loader.content.Loader;

public class MainActivity extends AppCompatActivity implements LoaderManager.LoaderCallbacks<Cursor>{

        EditText mEditTextWord;
        EditText mEditTextDefinition;
        DictionaryDatabase mDB;
        ListView mListView;
        DictionaryAdapter mAdapter;

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

            mDB = new DictionaryDatabase(this);

            mEditTextWord = findViewById(R.id.editTextWord);
            mEditTextDefinition = findViewById(R.id.editTextDefinition);
            Button buttonAddUpdate = findViewById(R.id.buttonAddUpdate);
            buttonAddUpdate.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    saveRecord();
                }
            });

            mListView = findViewById(R.id.listView);
            mListView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
                @Override
                public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                    Toast.makeText(MainActivity.this,
                            mDB.getDefinition(id),
                            Toast.LENGTH_SHORT).show();
                }
            });
            mListView.setOnItemLongClickListener(new AdapterView.OnItemLongClickListener() {
                @Override
                public boolean onItemLongClick(AdapterView<?> parent, View view, int position, long id) {
                    Toast.makeText(MainActivity.this, "Records deleted = " + mDB.deleteRecord(id),
                            Toast.LENGTH_SHORT).show();
                    LoaderManager.getInstance(MainActivity.this).restartLoader(0, null, MainActivity.this);
                    return true;
                }
            });
            LoaderManager.getInstance(this).initLoader(0, null, this);
            mAdapter = new DictionaryAdapter(this, mDB.getWordList(), 0);
            mListView.setAdapter(mAdapter);
        }

        private void saveRecord() {
            mDB.saveRecord(mEditTextWord.getText().toString(), mEditTextDefinition.getText().toString());
            mEditTextWord.setText("");
            mEditTextDefinition.setText("");
            LoaderManager.getInstance(MainActivity.this).restartLoader(0, null, MainActivity.this);
        }

        @Override
        public Loader<Cursor> onCreateLoader(int id, Bundle args){
            return new DictionaryLoader(this);
        }

        @Override
        public void onLoadFinished(Loader<Cursor> loader, Cursor data){
            mAdapter.swapCursor(data);
        }

        @Override
        public void onLoaderReset(Loader<Cursor> loader) {
            mAdapter.swapCursor(null);
        }

}