Demonstrates various possibilities to declare a val and the resulting bytecode

Main.scala

/**
 * Demonstrates various possibilities to declare a val and the resulting bytecode.
 *
 * Main takeaways are:
 *  - `private[this]` does not generate a getter and genertes direct field access
 *  - compile time constants are `final val x = e` with an optional modifier (§4.1)
 *    - final must be given, even if enclosing class is already final (§ 5.2 - 'final')
 *    - no type annotation may be present
 */
final class Main {

  /**
   * Generates getter:
   *
   * public java.lang.String foo1();
   *   1: getfield      #51                 // Field foo1:Ljava/lang/String;
   */
  val foo1 = "bar1"

  /**
   * Generates getter:
   *
   * private java.lang.String foo2();
   *   1: getfield      #55                 // Field foo2:Ljava/lang/String;
   */
  private val foo2 = "bar2"

  /** Doesn't generate a getter */
  private[this] val foo3 = "bar3"


  /**
   * Generates getter:
   *
   * public final java.lang.String foo4();
   *   0: ldc           #57                 // String bar4
   */
  final val foo4 = "bar4"

  /**
   * Generates getter:
   *
   * private final java.lang.String foo5();
   *   0: ldc           #59                 // String bar5
   */
  private final val foo5 = "bar5"

  /** Doesn't generate a getter */
  private[this] final val foo6 = "bar6"


  /**
   * Generates getter:
   *
   * public final java.lang.String foo7();
   *   1: getfield      #61                 // Field foo7:Ljava/lang/String;
   */
  final val foo7: String = "bar7"

  /**
   * Generates getter:
   *
   * public final java.lang.String foo8();
   *   1: getfield      #63                 // Field foo8:Ljava/lang/String;
   */
  private final val foo8: String = "bar8"

  /** Doesn't generate a getter */
  private[this] final val foo9: String = "bar9"


  def run() {
    println(foo1)  //  4: invokevirtual #71                 // Method foo1:()Ljava/lang/String;
    println(foo2)  // 14: invokespecial #77                 // Method foo2:()Ljava/lang/String;
    println(foo3)  // 24: getfield      #79                 // Field foo3:Ljava/lang/String;
    println(foo4)  // 33: ldc           #57                 // String bar4
    println(foo5)  // 41: ldc           #59                 // String bar5
    println(foo6)  // 49: ldc           #81                 // String bar6
    println(foo7)  // 58: invokevirtual #83                 // Method foo7:()Ljava/lang/String;
    println(foo8)  // 68: invokespecial #85                 // Method foo8:()Ljava/lang/String;
    println(foo9)  // 78: getfield      #87                 // Field foo9:Ljava/lang/String;
  }
}
object Main extends App { new Main().run() }