在 Android 上运行分屏视图

如何解决在 Android 上运行分屏视图

我想在应用运行后自动运行分屏查看模式。但是，我收到如下错误：

"java.lang.RuntimeException: 无法启动活动 ComponentInfo{com.example.myapplication/com.example.myapplication.MainActivity}: java.lang.NullPointerException: 尝试调用虚拟方法 'void com.example.myapplication. MyAccessibilityService.doAction()' 在空对象引用上"

我做错了什么？谢谢。

代码：

public class MainActivity extends AppCompatActivity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        System.out.println("Main app started!");
        MyAccessibilityService.instance.doAction();
        System.out.println("Main app ended!");
    }
    }




class MyAccessibilityService extends AccessibilityService {

    public static MyAccessibilityService instance;

    protected void onServiceConnected() {
        super.onServiceConnected();

        System.out.println("Accessibility was connected!");
        instance = this;
    }

    @Override
    public void onAccessibilityEvent(AccessibilityEvent event) {
    }

    @Override
    public void onInterrupt() {
    }

    public void doAction(){
        performGlobalAction(GLOBAL_ACTION_TOGGLE_SPLIT_SCREEN);

    }
}