需要声明可以获取"变量.

You need to declare that you can "get" the variable.

public string myProperty { get; } = "MY TEXT";

如果你真的想在代码中改变这个变量，你的类需要实现 INotifyPropertyChanged，否则它总是MY TEXT"

If you actually want to change this variable in code, your class will need to implement INotifyPropertyChanged, otherwise it will always be "MY TEXT"