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Java to Kotlin migration guides

连接字符串:

Java: “1” + “b” kotlin: “$a$b”
生成字符串:

Java: StringBuilder kotlin: buildString() // 底层也是使用StringBuilder
通过集合创建字符串:

Java: Stream API // Java List numbers = List.of(1, 2, 3, 4, 5, 6); String invertedOddNumbers = numbers .stream() .filter(it -> it % 2 != 0) .map(it -> -it) .map(Object::toString) .collect(Collectors.joining(", ")); System.out.println(invertedOddNumbers);

kotlin: joinToString() // Kotlin val numbers = listOf(1, 2, 3, 4, 5, 6) val invertedOddNumbers = numbers .filter { it % 2 != 0 } .joinToString{ “${-it}” } println(invertedOddNumbers)
字符串设置默认值:

Java: ternary operator kotlin: ifBlank()

fun main() { val name = getName().ifBlank { “John Doe” } println(name) }

fun getName(): String = if (Random.nextBoolean()) “” else “David”
替换字符:

Java: replaceFirst() replaceAll() kotlin: removeSurrounding()
替换事件:

Java: Patern, Matcher kotlin: Regex
分割字符串:

Java: split() kotlin: split()
获取子字符串:

Java: substring() kotlin: substringAfter()
多行字符串:

Java: String.join Java15: text blocks “”” “”” kotlin: “”””””