无法解决符号“窗口”错误

Sal*_*ati 3 java android android-activity android-studio

当我添加"this.requestWindowFeature(Window.FEATURE_NO_TITLE);"到活动中时,IDE会变红“窗口”字样,并在工具提示上通过“无法解析符号“窗口””警告我

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    this.requestWindowFeature(Window.FEATURE_NO_TITLE);
    setContentView(R.layout.activity_splash_screen);
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任何帮助,将不胜感激。