How do I convert Java source code file encoding from GBK to UTF-8?

Sometimes see the interesting demo, in the Headache Import Project code and workspace encoding is not the same when I try to open a notebook Class A class of replication,

Demo of the analogy is less can endure, the class of the demo when more than just rely on the other way today to find the imitation iOS style demo when really can not stand garbled, Sina a search, appear to force the tool class general idea quite simple is to find the path re-transcoding. Thank the author, respect the original.

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How do I convert Java source code file encoding from GBK to UTF-8?