android studio -为什么AS告诉我' (ob instanceof Button) '总是' fal

Question

为什么AS告诉我(ob instanceof Button)总是false ?

也给了'Cast to Button'一个"提示"。如果我接受了暗示，什么都不会改变。

  void setTextSizeForField(int textSize, Object ... obs){
    for(Object ob: obs)
           if (ob instanceof EditText) ((EditText) ob).setTextSize ( textSize );
      else if (ob instanceof TextView) ((TextView) ob).setTextSize ( textSize );
      else if (ob instanceof Button)   ((Button)   ob).setTextSize ( textSize/10 );
  }

消息的全文为:

Condition 'ob instanceof Button' is always 'false' less... (Ctrl+F1) 
This inspection analyzes method control and data flow to report possible conditions that are
 always true or false, expressions whose value is statically proven to be constant, and 
situations that can lead to nullability contract violations. 
Variables, method parameters and return values marked as @Nullable or @NotNull are 
treated as nullable (or not-null, respectively) and used during the analysis to check 
nullability contracts, e.g. report possible NullPointerException errors. 
More complex contracts can be defined using @Contract annotation, for example: 
@Contract("_, null -> null") — method returns null if its second argument is null
@Contract("_, null -> null; _, !null -> !null") — method returns null if
 its second argument is null and not-null otherwise
@Contract("true -> fail") — a typical assertFalse method which throws an
 exception if true is passed to it
The inspection can be configured to use custom @Nullable 
@NotNull annotations (by default the ones from annotations.jar will be used) 

我没有使用注释。

* EDIT *

如果我交换两个else if语句，我没有得到警告，代码运行良好。

所以我猜"没关系"可能是有序的，但是你认为AS在做什么?

Answer 1

文档显示Button扩展了TextView，因此永远不会采取分支。如果您将Button和TextView的检查倒置，则将采取不同的路径。