Extract constant is similar to Extract Local Variable, but you must select a static, constant expression, which the refactoring will convert to a static final constant.

Extract Constant与Extract Local Variable相似，但是您必须选择静态常量表达式，重构工具将会把它转换成静态的final常量。

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For whom thoughts of food, and the effects of food, are the constant, dreary background static to normal thought.

WSJ: Caitlin Moran on Women and Overeating: I Know Why the Fat Lady Sings