  Refactoring is an important activity that is frequently performed in software
development, and among them, Extract Method is known to be one of the most
frequently performed refactorings. The existing techniques for recommending
Extract Method refactoring calculate metrics from the source method and the
code fragments to be extracted to order the recommendation candidates. This
paper proposes a new technique for accurately recommending Extract Method
refactoring by considering whether code fragments are semantically coherent
chunks that can be given clear method names, in addition to the metrics used in
previous studies. As a criterion for the semantic coherency, the proposed
technique employs the probability (i.e. confidence) of the predicted method
names for the code fragments output by code2seq, which is a state-of-the-art
method name prediction technique. The evaluation experiment confirmed that the
proposed technique has higher correctness of recommendation than the existing
techniques.
