how can i code public class for SimpleCursorAdapter?

I am new to android and I need to use ListView for my project. I use a sample from the internet which has no public class for ListView so I am not able to code flexible. how can I code public class for this.

public class LIGHTS extends AppCompatActivity {

    ListView users_list;
    private DatabaseManager dbManager;
    private SimpleCursorAdapter adapter;
    private DatabaseHelper dbHelper;

    final String[] from = new String[]{dbHelper._ID, dbHelper.TITLE, dbHelper.DESC};
    final int[] to = new int[]{R.id.id, R.id.KEYCODE, R.id.NAME};

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

        dbManager = new DatabaseManager(this);
        dbManager.open();
        Cursor cursor = dbManager.fetch();

        users_list = findViewById(R.id.users_list);

        adapter = new SimpleCursorAdapter(this, R.layout.adapter, cursor, from, to, 0);
        users_list.setAdapter(adapter);}

and the fetch() is in below code in dbmanager:

    public Cursor fetch() {
        String[] columns = new String[]{dbHelper._ID, dbHelper.TITLE, dbHelper.DESC};
        Cursor cursor = database.query(dbHelper.TABLE_NAME, columns, null, null, null, null, null);
        if (cursor != null) {
            cursor.moveToFirst();
        }
        return cursor;
    }

Solution

Here's an example based upon your code that handles clicking a button for each item in the list.

If you click a switch then it displays the id of the item via a toast.

This utilises a Custom Adapter based upon (extends) the CursorAdapter class.

First the layout adapter.xml used for the item (should have the basics of your's and includes a switch who's id is the_switch) :-

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="horizontal"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
    <TextView
        android:id="@+id/id"
        android:layout_width="0dp"
        android:layout_weight="1"
        android:layout_height="wrap_content" />
    <TextView
        android:id="@+id/KEYCODE"
        android:layout_width="0dp"
        android:layout_weight="2"
        android:layout_height="wrap_content" />
    <TextView
        android:id="@+id/NAME"
        android:layout_width="0dp"
        android:layout_weight="6"
        android:layout_height="wrap_content" />
    <Switch
        android:id="@+id/the_switch"
        android:layout_width="0dp"
        android:layout_weight="1"
        android:layout_height="wrap_content"
        android:focusable="false"
        />
</LinearLayout>

The Activity Lights.java is now :-

public class Lights extends AppCompatActivity {

    ListView users_list, alt_users_list;
    private DatabaseManager dbManager;
    private MyCustomCursorAdapter adapter;
    //private DatabaseManager dbHelper; //?????? a second not needed
    Cursor cursor;
    Context mContext;

    //<<<<<<<<<< Not needed although could be passed
    //final String[] from = new String[]{DatabaseManager._ID, DatabaseManager.TITLE, DatabaseManager.DESC};
    //final int[] to = new int[]{R.id.id, R.id.KEYCODE, R.id.NAME};

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        mContext = this;
        setContentView(R.layout.activity_lights);
        startconnection(); //?????? dummied out
        users_list = findViewById(R.id.users_list);
        alt_users_list = findViewById(R.id.alt_users_list);

        dbManager = new DatabaseManager(this);
        dbManager.open();
        manageListView(); //Handles the ListView
    }

    // Moved here handles list refresh if called (e.g. in onResume)
    private void manageListView() {
        cursor = dbManager.fetch();
        //Setup the adapter if not already setup else swaps (refreshes) the cursor
        if (adapter == null) {
            adapter = new MyCustomCursorAdapter(this, cursor);
            users_list.setAdapter(adapter);
            users_list.setOnItemClickListener(new AdapterView.OnItemClickListener() {
                @Override
                public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                    Toast.makeText(mContext,"You clicked on the item with an ID of " + String.valueOf(id),Toast.LENGTH_SHORT).show();
                }
            });
        } else {
            adapter.swapCursor(cursor);
        }
    }
    private void startconnection(){}

    @Override
    protected void onDestroy() {
        super.onDestroy();
        // Close the Cursors when done with them
        cursor.close();
    }

    @Override
    protected void onResume() {
        super.onResume();
        // Refresh the listviews when returning to the activity
        manageListView();
    }
}

Comments try to explain changes (basically it is quite similar).
The biggest change is that the setting up of the listview has been moved to a method of it's own, which also handles refreshing the listview (redisplaying it after the underlying data has been changed).
The instantiation of the adapter is also simpler than for the SimpleCursorAdapter (the layout and column to view handling coded in the adapter).

The adapter myCustomAdapter.java is :-

public class MyCustomCursorAdapter extends CursorAdapter {

    public MyCustomCursorAdapter(Context context, Cursor c) {
        super(context, c, 0);
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        View view = super.getView(position, convertView, parent);
        if (position % 2 == 0) {
            view.setBackgroundColor(0xFFAAAAFF);
        } else {
            view.setBackgroundColor(0xAAAAAAFF);
        }
        return view;
    }

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

    @Override
    public void bindView(View view, Context context, Cursor cursor) {
        ((TextView)view.findViewById(R.id.id)).setText(cursor.getString(cursor.getColumnIndex(DatabaseManager._ID)));
        ((TextView)view.findViewById(R.id.KEYCODE)).setText(cursor.getString(cursor.getColumnIndex(DatabaseManager.TITLE)));
        ((TextView)view.findViewById(R.id.NAME)).setText(cursor.getString(cursor.getColumnIndex(DatabaseManager.DESC)));

        Switch thisswitch = view.findViewById(R.id.the_switch);
        thisswitch.setTag(cursor.getString(cursor.getColumnIndex(DatabaseManager._ID)));
        thisswitch.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
            @Override
            public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
                Toast.makeText(buttonView.getContext(),
                        "You clicked the switch for ID " + (String) buttonView.getTag() +
                                " the status is now " + (new Boolean(isChecked)).toString(),
                        Toast.LENGTH_SHORT)
                        .show()
                ;
            }
        });
    }
}

bindView has primarily been used it :-
- binds the values from the columns of the cursor to the views for each item
- and in this case sets the tag of the switch to the id and then adds an onCheckChangedListener for the Button.
bindView has the advantage that the cursor and context are passed to it.
getView can also be used, it has the advantage of having the position of the item in the list passed.
In this case it has been used to alternate the background colour for each item.

Result

Here's a screen shot showing the toast (note testing data was added to the underlying database, so this will obviously vary from yours) :-

Additional

It might be that you need to handle the switch check change in the owning activity.

The following changes show a basic means, via an interface, of handling the switch event in the activity, rather than in the adapter.

First the interface myOnCheckedChangedInterface.java

public interface myOnCheckedChangedInterface {
    void myOnCheckedChangedHandler(String id, boolean check_status);
}

Second change Lights.java by adding the handler method myOnCheckedChangedHandler

@Override
public void myOnCheckedChangedHandler(String id, boolean check_status) {
    Toast.makeText(
            this,
            "You changed the status for the row with an id of " + id +
                    " the status is now " + new Boolean(check_status).toString(),
            Toast.LENGTH_SHORT).show();
}

Ignore the error that the method doesn't override method from it's superclass.

Third change the Class declaration to implement the interface by adding implements myOnCheckedChangedInterface as per :-

public class Lights extends AppCompatActivity implements myOnCheckedChangedInterface {

Lastly change MyCustomCursorAdapter to be able to call the myOnCheckedChangedHandler

e.g.

public class MyCustomCursorAdapter extends CursorAdapter {
    Lights calling_activity; //<<<<<<<<<<@@@@@@@@@@@ ADDED for interface

    public MyCustomCursorAdapter(Context context, Cursor c) {
        super(context, c, 0);
        this.calling_activity = (Lights) context; //<<<<<<<<<<@@@@@@@@@@@ ADDED for interface
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        View view = super.getView(position, convertView, parent);
        if (position % 2 == 0) {
            view.setBackgroundColor(0xFFAAAAFF);
        } else {
            view.setBackgroundColor(0xAAAAAAFF);
        }
        return view;
    }

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

    @Override
    public void bindView(View view, Context context, Cursor cursor) {
        ((TextView)view.findViewById(R.id.id)).setText(cursor.getString(cursor.getColumnIndex(DatabaseManager._ID)));
        ((TextView)view.findViewById(R.id.KEYCODE)).setText(cursor.getString(cursor.getColumnIndex(DatabaseManager.TITLE)));
        ((TextView)view.findViewById(R.id.NAME)).setText(cursor.getString(cursor.getColumnIndex(DatabaseManager.DESC)));

        Switch thisswitch = view.findViewById(R.id.the_switch);
        thisswitch.setTag(cursor.getString(cursor.getColumnIndex(DatabaseManager._ID)));
        thisswitch.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
            @Override
            public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
                /**
                Toast.makeText(buttonView.getContext(),
                        "You clicked the switch for ID " + (String) buttonView.getTag() +
                                " the status is now " + (new Boolean(isChecked)).toString(),
                        Toast.LENGTH_SHORT)
                        .show()
                **/
                calling_activity.myOnCheckedChangedHandler((String)buttonView.getTag(),isChecked); //<<<<<<<<<<@@@@@@@@@@@ ADDED for interface
            }
        });
    }
}

See commments with //<<<<<<<<<<@@@@@@@@@@@ ADDED for interface for changes
The original Toast has been commented out as it is no longer needed
Note this isn't the tidiest way as the Adapter is tied to a Lights activity, it's just meant to be a simple example.