How Java fakes closures.

FinalTest.java

package lambda;

public class FinalTest {

  public static Runnable create(final int limit) {
    return new Runnable() {

      @Override
      public void run() {
        for (int i = 0; i < limit; ++i) {
          System.out.println(i);
        }
      }
    };
  }

}

FinalTestDis.java

Classfile /C:/Users/Robert/workspace/c.l.j.p/bin/classes/lambda/FinalTest.class
  Last modified 07.01.2013; size 450 bytes
  MD5 checksum b368e288e05b1d73bb6568fecffe6629
  Compiled from "FinalTest.java"
public class lambda.FinalTest
  SourceFile: "FinalTest.java"
  InnerClasses:
       #16; //class lambda/FinalTest$1
  minor version: 0
  major version: 50
  flags: ACC_PUBLIC, ACC_SUPER

Constant pool:
   #1 = Class              #2             //  lambda/FinalTest
   #2 = Utf8               lambda/FinalTest
   #3 = Class              #4             //  java/lang/Object
   #4 = Utf8               java/lang/Object
   #5 = Utf8               <init>
   #6 = Utf8               ()V
   #7 = Utf8               Code
   #8 = Methodref          #3.#9          //  java/lang/Object."<init>":()V
   #9 = NameAndType        #5:#6          //  "<init>":()V
  #10 = Utf8               LineNumberTable
  #11 = Utf8               LocalVariableTable
  #12 = Utf8               this
  #13 = Utf8               Llambda/FinalTest;
  #14 = Utf8               create
  #15 = Utf8               (I)Ljava/lang/Runnable;
  #16 = Class              #17            //  lambda/FinalTest$1
  #17 = Utf8               lambda/FinalTest$1
  #18 = Methodref          #16.#19        //  lambda/FinalTest$1."<init>":(I)V
  #19 = NameAndType        #5:#20         //  "<init>":(I)V
  #20 = Utf8               (I)V
  #21 = Utf8               limit
  #22 = Utf8               I
  #23 = Utf8               SourceFile
  #24 = Utf8               FinalTest.java
  #25 = Utf8               InnerClasses
{
  public lambda.FinalTest();
    Signature: ()V
    flags: ACC_PUBLIC

    LineNumberTable:
      line 3: 0
    LocalVariableTable:
      Start  Length  Slot  Name   Signature
             0       5     0  this   Llambda/FinalTest;
    Code:
      stack=1, locals=1, args_size=1
         0: aload_0       
         1: invokespecial #8                  // Method java/lang/Object."<init>":()V
         4: return        
      LineNumberTable:
        line 3: 0
      LocalVariableTable:
        Start  Length  Slot  Name   Signature
               0       5     0  this   Llambda/FinalTest;

  public static java.lang.Runnable create(int);
    Signature: (I)Ljava/lang/Runnable;
    flags: ACC_PUBLIC, ACC_STATIC

    LineNumberTable:
      line 6: 0
    LocalVariableTable:
      Start  Length  Slot  Name   Signature
             0       9     0 limit   I
    Code:
      stack=3, locals=1, args_size=1
         0: new           #16                 // class lambda/FinalTest$1
         3: dup           
         4: iload_0       
         5: invokespecial #18                 // Method lambda/FinalTest$1."<init>":(I)V
         8: areturn       
      LineNumberTable:
        line 6: 0
      LocalVariableTable:
        Start  Length  Slot  Name   Signature
               0       9     0 limit   I
}
Classfile /C:/Users/Robert/workspace/c.l.j.p/bin/classes/lambda/FinalTest$1.class
  Last modified 07.01.2013; size 715 bytes
  MD5 checksum 86664064f30ce0008e5316c53788f7ab
  Compiled from "FinalTest.java"
class lambda.FinalTest$1 implements java.lang.Runnable
  SourceFile: "FinalTest.java"
  EnclosingMethod: #38.#40                // lambda.FinalTest.create
  InnerClasses:
       #1; //class lambda/FinalTest$1
  minor version: 0
  major version: 50
  flags: ACC_SUPER

Constant pool:
   #1 = Class              #2             //  lambda/FinalTest$1
   #2 = Utf8               lambda/FinalTest$1
   #3 = Class              #4             //  java/lang/Object
   #4 = Utf8               java/lang/Object
   #5 = Class              #6             //  java/lang/Runnable
   #6 = Utf8               java/lang/Runnable
   #7 = Utf8               val$limit
   #8 = Utf8               I
   #9 = Utf8               <init>
  #10 = Utf8               (I)V
  #11 = Utf8               Code
  #12 = Fieldref           #1.#13         //  lambda/FinalTest$1.val$limit:I
  #13 = NameAndType        #7:#8          //  val$limit:I
  #14 = Methodref          #3.#15         //  java/lang/Object."<init>":()V
  #15 = NameAndType        #9:#16         //  "<init>":()V
  #16 = Utf8               ()V
  #17 = Utf8               LineNumberTable
  #18 = Utf8               LocalVariableTable
  #19 = Utf8               this
  #20 = Utf8               Llambda/FinalTest$1;
  #21 = Utf8               run
  #22 = Fieldref           #23.#25        //  java/lang/System.out:Ljava/io/PrintStream;
  #23 = Class              #24            //  java/lang/System
  #24 = Utf8               java/lang/System
  #25 = NameAndType        #26:#27        //  out:Ljava/io/PrintStream;
  #26 = Utf8               out
  #27 = Utf8               Ljava/io/PrintStream;
  #28 = Methodref          #29.#31        //  java/io/PrintStream.println:(I)V
  #29 = Class              #30            //  java/io/PrintStream
  #30 = Utf8               java/io/PrintStream
  #31 = NameAndType        #32:#10        //  println:(I)V
  #32 = Utf8               println
  #33 = Utf8               i
  #34 = Utf8               StackMapTable
  #35 = Utf8               SourceFile
  #36 = Utf8               FinalTest.java
  #37 = Utf8               EnclosingMethod
  #38 = Class              #39            //  lambda/FinalTest
  #39 = Utf8               lambda/FinalTest
  #40 = NameAndType        #41:#42        //  create:(I)Ljava/lang/Runnable;
  #41 = Utf8               create
  #42 = Utf8               (I)Ljava/lang/Runnable;
  #43 = Utf8               InnerClasses
{
  private final int val$limit;
    Signature: I
    flags: ACC_PRIVATE, ACC_FINAL, ACC_SYNTHETIC



  lambda.FinalTest$1(int);
    Signature: (I)V
    flags: 

    LineNumberTable:
      line 1: 0
      line 6: 5
    LocalVariableTable:
      Start  Length  Slot  Name   Signature
             0      10     0  this   Llambda/FinalTest$1;
    Code:
      stack=2, locals=2, args_size=2
         0: aload_0       
         1: iload_1       
         2: putfield      #12                 // Field val$limit:I
         5: aload_0       
         6: invokespecial #14                 // Method java/lang/Object."<init>":()V
         9: return        
      LineNumberTable:
        line 1: 0
        line 6: 5
      LocalVariableTable:
        Start  Length  Slot  Name   Signature
               0      10     0  this   Llambda/FinalTest$1;

  public void run();
    Signature: ()V
    flags: ACC_PUBLIC

    LineNumberTable:
      line 10: 0
      line 11: 5
      line 10: 12
      line 13: 23
    LocalVariableTable:
      Start  Length  Slot  Name   Signature
             0      24     0  this   Llambda/FinalTest$1;
             2      21     1     i   I
    Code:
      stack=2, locals=2, args_size=1
         0: iconst_0      
         1: istore_1      
         2: goto          15
         5: getstatic     #22                 // Field java/lang/System.out:Ljava/io/PrintStream;
         8: iload_1       
         9: invokevirtual #28                 // Method java/io/PrintStream.println:(I)V
        12: iinc          1, 1
        15: iload_1       
        16: aload_0       
        17: getfield      #12                 // Field val$limit:I
        20: if_icmplt     5
        23: return        
      LineNumberTable:
        line 10: 0
        line 11: 5
        line 10: 12
        line 13: 23
      LocalVariableTable:
        Start  Length  Slot  Name   Signature
               0      24     0  this   Llambda/FinalTest$1;
               2      21     1     i   I
      StackMapTable: number_of_entries = 2
           frame_type = 252 /* append */
             offset_delta = 5
        locals = [ int ]
           frame_type = 9 /* same */

}