I have seen variables like _ image and was wondering what _ meant?
12 Answers
The use of two underscores (`__') in identifiers is reserved for the compiler's internal use according to the ANSI-C standard.
Underscores (`_') are often used in names of library functions (such as "_main" and "_exit"). In order to avoid collisions, do not begin an identifier with an underscore.
To avoid reserved keywords, or in reserved keywords, making them more easily avoided. A single underscore is discouraged and reserved in JavaSE9.
Basically it is telling that the developer should provide the definition . In short it defines it does not have any definition .
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