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kotlin collections

kotlin collections List, 一个有序集合, 通过下标访问元素, 元素可以重复 Set, 一个数学抽象集合, 无序, 唯一. 一般Map的key就是set. 默认LinkedHashSet, HashSet Map(dictionary), key-value pairs. key是唯一的, 并且会关联一个value. value可以重复. 默认LinkedHashMap, HashMap kotlin有 read-only 和 mutable read-only 集合是convariant; mutable 不是convariant的 Constructing collections Construct from elemen...

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macos install 2.7

macos install 2.7 brew install openssl openssl@1.1 readline sqlite3 xz zlib pyenv export LDFLAGS="-L/opt/homebrew/opt/openssl@1.1/lib" export CPPFLAGS="-I/opt/homebrew/opt/openssl@1.1/include" pyenv install 2.7.18 Reference

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Java to Kotlin migration guides

Java to Kotlin migration guides String 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() ...

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kotlin jvm

kotlin jvm kotlin多平台开发支持: Android and iOS (在Alpha阶段) JVM JavaScript Native Scripting Comparison to java Some Java issues addressed in Kotlin: Null references are controlled by the type system. No raw types Arrays in Kotlin are invariant Kotlin has proper function types, as op...

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kotlin reflection

kotlin reflection dependencies { implementation("org.jetbrains.kotlin:kotlin-reflect:1.7.20") } <dependencies> <dependency> <groupId>org.jetbrains.kotlin</groupId> <artifactId>kotlin-reflect</artifactId> </dependency> </dependencies> references class references ...

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kotlin destructuring declarations

kotlin destructuring declarations val (name, age) = person 被翻译成: val name = person.component1() val age = person.component2() for ((a, b) in collection) { ... } Reference

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kotlin this

kotlin this To denote the current receiver, you use this expressions: * In a member of a class, this refers to the current object of that class. * In an extension function or a function literal with receiver this denotes the receiver parameter that is passed on the left-hand side of a dot. If this has no qualifiers, it refers to the innermo...

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