Java Math, StringBuilder, Collection 공식문서
https://docs.oracle.com/javase/8/docs/api/java/lang/StringBuilder.html
StringBuilder (Java Platform SE 8 )
Inserts the string into this character sequence. The characters of the String argument are inserted, in order, into this sequence at the indicated offset, moving up any characters originally above that position and increasing the length of this sequence by
docs.oracle.com
https://docs.oracle.com/javase/8/docs/api/java/lang/Math.html
Math (Java Platform SE 8 )
Returns the value of the first argument raised to the power of the second argument. Special cases: If the second argument is positive or negative zero, then the result is 1.0. If the second argument is 1.0, then the result is the same as the first argument
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https://docs.oracle.com/javase/8/docs/api/java/util/Collection.html
Collection (Java Platform SE 8 )
Compares the specified object with this collection for equality. While the Collection interface adds no stipulations to the general contract for the Object.equals, programmers who implement the Collection interface "directly" (in other words, create a clas
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