é•·ã„æ–‡å—列を作æˆã™ã‚‹ - StringBuilder | Scala Cookbooké•·ã„æ–‡å—列を作æˆã™ã‚‹ã€‚ 方法 çŸã„æ–‡å—列ã®å ´åˆã€‚ val s = "Hello" + " World!!" æ–‡å—列をãŸãã•ã‚“連çµã—ã¦ã„ãå ´åˆã¯ã€StringBuilderを使用ã™ã‚‹ã€‚ Good val b = new StringBuilder for(i <- 0 until 10) { if(i > 0) b.append(", ") b.append(i) } val s = b.result // s = "0, 1, 2, 3, 4, 5, 6, 7, 8, 9" Bad var s = "" for(i <- 0 until 10) { if(i > 0) s += ", " // æ–‡å—列ã®ã‚³ãƒ”ãƒ¼ã‚’ä½œæˆ s += i　// æ–‡å—列ã®ã‚³ãƒ”ãƒ¼ã‚’ä½œæˆ } // s = "0, 1, 2, 3, 4, 5, 6, 7, 8, 9" +=ã§Stringã«å¯¾ã—ã¦æ–‡å—列を連çµã—ã¦ã„ãã¨ã€æ–‡å—
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