Kotlin的独门秘籍Reified实化类型参数(下篇)

    fun main(args: Array<String>) {
    val list1: List<Int> = listOf(1,2,3,4)
    val list2: List<String> = listOf("a","b","c","d")
    println(list1)
    println(list2)
    }

    @Metadata(
       mv = {1, 1, 11},
       bv = {1, 0, 2},
       k = 2,
       d1 = {"\u0000\u0014\n\u0000\n\u0002\u0010\u0002\n\u0000\n\u0002\u0010\u0011\n\u0002\u0010\u000e\n\u0002\b\u0002\u001a\u0019\u0010\u0000\u001a\u00020\u00012\f\u0010\u0002\u001a\b\u0012\u0004\u0012\u00020\u00040\u0003¢\u0006\u0002\u0010\u0005¨\u0006\u0006"},
       d2 = {"main", "", "args", "", "", "([Ljava/lang/String;)V", "Lambda_main"}
    )
    public final class GenericKtKt {
       public static final void main(@NotNull String[] args) {
      Intrinsics.checkParameterIsNotNull(args, "args");
      List list1 = CollectionsKt.listOf(new Integer[]{1, 2, 3, 4});//List原生类型
      List list2 = CollectionsKt.listOf(new String[]{"a", "b", "c", "d"});//List原生类型
      System.out.println(list1);
      System.out.println(list2);
       }
    }

    if(value is List<String>){...}//一般情况下这样的代码不会被编译通过

    if(value is List){...}

    if(value is List<*>){...}

    fun printNumberList(collection: Collection<String>) {
    if(collection is List<String>){...} //在这里这样写法是合法的。
    }

    package com.mikyou.kotlin.generic
    
    
    fun main(args: Array<String>) {
    printNumberList(listOf(1, 2, 3, 4, 5))//传入List<Int>类型的数据
    }
    
    fun printNumberList(collection: Collection<*>) {
    val numberList = collection as List<Int>//强转成List<Int>
    println(numberList)
    }

    package com.mikyou.kotlin.generic
    
    
    fun main(args: Array<String>) {
    printNumberList(listOf("a", "b", "c", "d"))//传入List<String>类型的数据
    }
    
    fun printNumberList(collection: Collection<*>) {
    val numberList = collection as List<Int>
    //这里强转成List<Int>，并不会报错，输出正常，
    //但是需要注意不能默认把类型实参当做Int来操作，因为擦除无法确定当前类型实参，否则有可能出现运行时异常
    println(numberList)
    }

    fun main(args: Array<String>) {
    printNumberList(setOf(1, 2, 3, 4, 5))
    }
    
    fun printNumberList(collection: Collection<*>) {
    val numberList = collection as List<Int>
    println(numberList)
    }

    package com.mikyou.kotlin.generic
    
    
    fun main(args: Array<String>) {
    printNumberList(listOf("a", "b", "c", "d"))
    }
    
    fun printNumberList(collection: Collection<*>) {
    val numberList = collection as List<Int>
    println(numberList.sum())
    }

    inline fun <reified T> isInstanceOf(value: Any): Boolean = value is T

    inline fun <reified T: Activity> Context.startActivity(vararg params: Pair<String, Any?>) =
        AnkoInternals.internalStartActivity(this, T::class.java, params)

    class SplashActivity : BizActivity() {
    
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.biz_app_activity_welcome)
        startActivityKt<AccountActivity>()//只需这样就直接启动了AccountActivity了，指明了类型形参上界约束Activity
    }
    }
    
    inline fun <reified T : Activity> Context.startActivityKt(vararg params: Pair<String, Any?>) =
        AnkoInternals.internalStartActivity(this, T::class.java, params)

    //函数定义反编译
     private static final void startActivityKt(@NotNull Context $receiver, Pair... params) {
      Intrinsics.reifiedOperationMarker(4, "T");
      AnkoInternals.internalStartActivity($receiver, Activity.class, params);//注意点一: 由于泛型擦除的影响，编译后原来传入类型实参AccountActivity被它形参上界约束Activity替换了，所以这里证明了我们之前的分析。
       }
    //函数调用点反编译
    protected void onCreate(@Nullable Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      this.setContentView(2131361821);
      Pair[] params$iv = new Pair[0];
      AnkoInternals.internalStartActivity(this, AccountActivity.class, params$iv);
      //注意点二: 可以看到这里函数调用并不是简单函数调用，而是根据此次调用明确的类型实参AccountActivity.class替换定义处的Activity.class,然后生成新的字节码插入到调用点。
    }

    class SplashActivity : BizActivity() {
    
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.biz_app_activity_welcome)
        startActivityKt<AccountActivity>()
    }
    }
    
    inline fun <reified T : Activity> Context.startActivityKt(vararg params: Pair<String, Any?>) {
    println("call before")
    AnkoInternals.internalStartActivity(this, T::class.java, params)
    println("call after")
    }

    private static final void startActivityKt(@NotNull Context $receiver, Pair... params) {
      String var3 = "call before";
      System.out.println(var3);
      Intrinsics.reifiedOperationMarker(4, "T");
      AnkoInternals.internalStartActivity($receiver, Activity.class, params);
      var3 = "call after";
      System.out.println(var3);
       }
    
       protected void onCreate(@Nullable Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      this.setContentView(2131361821);
      Pair[] params$iv = new Pair[0];
      String var4 = "call before";
      System.out.println(var4);
      AnkoInternals.internalStartActivity(this, AccountActivity.class, params$iv);//替换成确切的类型实参AccountActivity.class
      var4 = "call after";
      System.out.println(var4);
       }