Why end methods in java are invoked with invokevirtual opcode

Question

final methods in java cannot be overridden by an inherited class. But why are the latest methods called using invokevirtual instead of invokespecial.

Answer 1

Modifier semantics are finalapplied only by bytecode compiler.

JavaSE7 Specification Link Some other finalkeyword examples .

invokespecial invokevirtual , invokevirtual , . invokespecial , .

, - INVOKEVIRTUAL, , .

final.

CounterPoint.java

public class CounterPoint extends Point {

    private static final AtomicInteger counter = new AtomicInteger();

    public CounterPoint(int x, int y) {
        super(x, y);
        counter.incrementAndGet();
    }

    public static String numberCreated() {
        return counter.toString();
    }

}

ByteCode of CounterPoint

// class version 52.0 (52)
// access flags 0x21
public class com/xetrasu/CounterPoint extends java/awt/Point  {

  // compiled from: CounterPoint.java

  // access flags 0x1A
  private final static Ljava/util/concurrent/atomic/AtomicInteger; counter

  // access flags 0x1
  public <init>(II)V
   L0
    LINENUMBER 11 L0
    ALOAD 0
    ILOAD 1
    ILOAD 2
    INVOKESPECIAL java/awt/Point.<init> (II)V
   L1
    LINENUMBER 12 L1
    GETSTATIC com/xetrasu/CounterPoint.counter : Ljava/util/concurrent/atomic/AtomicInteger;
    INVOKEVIRTUAL java/util/concurrent/atomic/AtomicInteger.incrementAndGet ()I
    POP
   L2
    LINENUMBER 13 L2
    RETURN
   L3
    LOCALVARIABLE this Lcom/xetrasu/CounterPoint; L0 L3 0
    LOCALVARIABLE x I L0 L3 1
    LOCALVARIABLE y I L0 L3 2
    MAXSTACK = 3
    MAXLOCALS = 3

  // access flags 0x9
  public static numberCreated()Ljava/lang/String;
   L0
    LINENUMBER 16 L0
    GETSTATIC com/xetrasu/CounterPoint.counter : Ljava/util/concurrent/atomic/AtomicInteger;
    INVOKEVIRTUAL java/util/concurrent/atomic/AtomicInteger.toString ()Ljava/lang/String;
    ARETURN
    MAXSTACK = 1
    MAXLOCALS = 0

  // access flags 0x8
  static <clinit>()V
   L0
    LINENUMBER 8 L0
    NEW java/util/concurrent/atomic/AtomicInteger
    DUP
    INVOKESPECIAL java/util/concurrent/atomic/AtomicInteger.<init> ()V
    PUTSTATIC com/xetrasu/CounterPoint.counter : Ljava/util/concurrent/atomic/AtomicInteger;
    RETURN
    MAXSTACK = 2
    MAXLOCALS = 0
}

AtomicInteger.java

public class AtomicInteger extends Number implements java.io.Serializable {
    public String toString() {
        return Integer.toString(get());
    }
    public final int incrementAndGet() {
        return unsafe.getAndAddInt(this, valueOffset, 1) + 1;
    }
}