public class MainActivity extends AppCompatActivity {
    static class Timer {
        static boolean active = true;
        static int level = 100;
        static int start = 3650;
        static int stop = 7200;
    }

static class Pump{
    static boolean active = true;
    static int start = 3600;
    static int working = 3000;
    }

static class CO2{
    static boolean active = true;
    static Timer[] timerCO2 = new Timer[4];
    }
static class Channel{
        static boolean active = true;
        static int startDay = 3600;
        static int stopDay = 82800;
        static Timer[] timer = new Timer[4];
    }
    Channel[] channel = new Channel[9];

public int chNum;

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

final Switch switchCh = (Switch) findViewById(R.id.switchCh);
final ArrayAdapter<String> adapterCh = new ArrayAdapter<String>(this, android.R.layout.simple_spinner_item, ch);
    adapterCh.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
    Spinner spinnerCh = (Spinner) findViewById(R.id.spinnerCh);
    spinnerCh.setAdapter(adapterCh);
    spinnerCh.setSelection(0);
    spinnerCh.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
        @Override
        public void onItemSelected(AdapterView<?> parent, View view,
                                   int position, long id) {
            chNum = position;
            switchCh.setChecked(channel[chNum].active);
            System.out.println ("spinnerCh " + chNum + " " + channel[chNum].active);

        }
        @Override
        public void onNothingSelected(AdapterView<?> arg0) {
        }
    });

    switchCh.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
        @Override
        public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
            channel[chNum].active = isChecked;
            System.out.println ("switchCh " + chNum + " " + channel[chNum].active);
        }
    });

}
}

switchCh.setOnCheckedChangeListener (null);
switchCh.setChecked (..);
switchCh.setOnCheckedChangeListener ( листенер сохраненый в переменную в OnCreate);