<1.慣例，來布局>

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:orientation="vertical">    <SeekBar        android:id="@+id/seek_bar"        android:layout_width="match_parent"        android:layout_height="wrap_content" />    <TextView        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:id="@+id/showSeek"        android:textSize="20.0sp"        android:gravity="center"/></LinearLayout>
<2.源碼>
public class MainActivity extends AppCompatActivity {    PRivate SeekBar seekBar;    private TextView showseek;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        init();        seekBar.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() {            @Override            public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {            }            @Override            public void onStartTrackingTouch(SeekBar seekBar) {            }            @Override            public void onStopTrackingTouch(SeekBar seekBar) {                update((float)seekBar.getProgress()/10);            }        });    }    //實例化控件    private void init(){        seekBar= (SeekBar) findViewById(R.id.seek_bar);        showseek= (TextView) findViewById(R.id.showSeek);        //亮度是從0~1中的一個浮點數，由于getProess得到的是Int型，所以擴大10倍，賦值時除以10        seekBar.setMax(10);    }    private void update(float b){        //取得window屬性保存在layoutParams中        WindowManager.LayoutParams layoutParams = getWindow().getAttributes();        layoutParams.screenBrightness = b;        getWindow().setAttributes(layoutParams);        //顯示修改后的亮度        layoutParams = getWindow().getAttributes();        showseek.setText("當前亮度:"+String.valueOf(layoutParams.screenBrightness));    }}