아래소스에서 조절한 화면 밝기를 메인 엑티비티에 적용시킬려면 어떻게 해야하나요???

public class SeekbarActivity extends Activity {
 
    private View panel;
    private SeekBar seekbar;
    private TextView text01;
    public int brightness =50;

    
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.seekbar);
       
        panel = findViewById(R.id.panel01);
        text01 = (TextView) findViewById(R.id.text01);
        seekbar = (SeekBar) findViewById(R.id.seekbar01);

        Button showBtn = (Button) findViewById(R.id.showBtn);
        showBtn.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {
                      //버튼 클릭해서 메인 엑티비티에 밝기 적용 시키려고 하는데 방법을 모르겠습니다.
            }
        });
       
        showPanel();
        seekbar.setOnSeekBarChangeListener(new MyOnSeekBarChangeListener());
        getWindow().addFlags(android.view.WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);

       
    }
   
    private void showPanel() {
        seekbar.setProgress(this.brightness);
        panel.setVisibility(View.VISIBLE);
      }

    public void setBrightness(int value) {
        if (value < 10) {
            value = 10;
        } else if (value > 100) {
            value = 100;
        }
       
        brightness = value;
        WindowManager.LayoutParams params = getWindow().getAttributes();
        params.screenBrightness = (float) value / 100;       
        getWindow().setAttributes(params);
       
        Intent resultIntent = new Intent();
        resultIntent.putExtra("bright", value);
        setResult(2, resultIntent);
       
       
    }

     
    class MyOnSeekBarChangeListener implements OnSeekBarChangeListener {
     public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {
            setBrightness(progress);
            text01.setText("밝기 수준 : " + progress);
        }

        public void onStartTrackingTouch(SeekBar seekBar) {
        }

        public void onStopTrackingTouch(SeekBar seekBar) {
           // hidePanel();
        }
    }
   
} 

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