小编Cor*_* Wu的帖子

是否有更简洁的方法来编写此方法？优选地,我不需要匹配所有有效类型,而是允许每个具有*方法的Type.另外,有没有办法asInstanceOf[T]在最后不要求？

def expr_neg[T <: AnyVal](value: T): T = value match {
  case int: Int => (int * -1).asInstanceOf[T]
  case long: Long => (long * -1).asInstanceOf[T]
  case float: Float => (float * -1).asInstanceOf[T]
  case double: Double => (double * -1).asInstanceOf[T]
}

我试图使我的count变量同步get和私人帮助函数基于其他成员进行设置.多个线程调用每一个setCount()作为deadlineNoteVisible和referencesAvailable变化.

随着synchronized对刚刚setCount()方法,一切都很好,但是当我添加synchronized(this)到get()电话,我得到:

OutOfMemoryError: Failed to allocate a 57993496 byte allocation with 16764448 free bytes and 32MB until OOM

代码(用Kotlin编写):

var count: Int = 0
    // Why does adding synchronized here explode?
    get() = synchronized(this) { count }
    private set

private fun setCount() {
    synchronized(this) {
        count = 0
        if (deadlineNoteVisible) {
            count += 1
        }
        if (referencesAvailable) {
            count += 1
        } …

我正在运行代码:https: //github.com/bkiers/antlr4-csv-demo.我想通过添加以下行来查看词法分析器分析的标记:

System.out.println("Number of tokens: " + tokens.getTokens().size())

到Main.java:

public static void main(String[] args) throws Exception {  
    // the input source  
    String source =   
        "aaa,bbb,ccc" + "\n" +   
        "\"d,\"\"d\",eee,fff";  

    // create an instance of the lexer  
    CSVLexer lexer = new CSVLexer(new ANTLRInputStream(source));  

    // wrap a token-stream around the lexer  
    CommonTokenStream tokens = new CommonTokenStream(lexer);  

    // look at tokens analyzed
    System.out.println("Number of tokens: " + tokens.getTokens().size())

    // create the parser  
    CSVParser parser = new CSVParser(tokens);  

    // invoke the …

我有地图的String,以FunctionS的所有细节的是在语言的有效功能.当我向地图添加一个函数时,我需要指定类型(在本例中Int).

var functionMap: Map[String, (Nothing) => Any] = Map[String, (Nothing) => Any]()

functionMap += ("Neg" -> expr_neg[Int])

def expr_neg[T: Numeric](value: T)(implicit n: Numeric[T]): T = {
  n.negate(value)
} 

相反,我该怎么做:

functionMap += ("Neg" -> expr_neg)

没有,[Int]并在我打电话后添加它:

(unaryFunctionMap.get("abs").get)[Int](-45)