question: @ Override public final String toString ( ) { StringBuilder builder = new StringBuilder ( ) ; builder . append ( "[ " ) ; for ( LongWritable v : this . vertices ) { builder . append ( v . toString ( ) ) ; builder . append ( " " ) ; } builder . append ( " | " + score + ", " + innerScore + ", " + boundaryScore + " ]" ) ; return builder . toString ( ) ; }
target:  Convert object to string object.