Generics in Java

gistfile1.java

package oss.alphazero.temp;
import java.util.Map;

public class GenericFoo<K, V, T extends Map<K, V>> {

}

-- javap --

Compiled from "GenericFoo.java"
public class oss.alphazero.temp.GenericFoo extends java.lang.Object
  SourceFile: "GenericFoo.java"
  Signature: length = 0x2
   00 13 
  minor version: 0
  major version: 50
  Constant pool:
const #1 = class	#2;	//  oss/alphazero/temp/GenericFoo
const #2 = Asciz	oss/alphazero/temp/GenericFoo;
const #3 = class	#4;	//  java/lang/Object
const #4 = Asciz	java/lang/Object;
const #5 = Asciz	<init>;
const #6 = Asciz	()V;
const #7 = Asciz	Code;
const #8 = Method	#3.#9;	//  java/lang/Object."<init>":()V
const #9 = NameAndType	#5:#6;//  "<init>":()V
const #10 = Asciz	LineNumberTable;
const #11 = Asciz	LocalVariableTable;
const #12 = Asciz	this;
const #13 = Asciz	Loss/alphazero/temp/GenericFoo;;
const #14 = Asciz	LocalVariableTypeTable;
const #15 = Asciz	Loss/alphazero/temp/GenericFoo<TK;TV;TT;>;;
const #16 = Asciz	SourceFile;
const #17 = Asciz	GenericFoo.java;
const #18 = Asciz	Signature;
const #19 = Asciz	<K:Ljava/lang/Object;V:Ljava/lang/Object;T::Ljava/util/Map<TK;TV;>;>Ljava/lang/Object;;

{
public oss.alphazero.temp.GenericFoo();
  Code:
   Stack=1, Locals=1, Args_size=1
   0:	aload_0
   1:	invokespecial	#8; //Method java/lang/Object."<init>":()V
   4:	return
  LineNumberTable: 
   line 5: 0

  LocalVariableTable: 
   Start  Length  Slot  Name   Signature
   0      5      0    this       Loss/alphazero/temp/GenericFoo;

  LocalVariableTypeTable: length = 0xC
   00 01 00 00 00 05 00 0C 00 0F 00 00 

}

// ========= Specialization w/ concrete type ==========

package oss.alphazero.temp;
import java.util.Map;

public class FooDictionary extends GenericFoo<String, Object, Map<String, Object>>{
}


-- javap --

Compiled from "FooDictionary.java"
public class oss.alphazero.temp.FooDictionary extends oss.alphazero.temp.GenericFoo
  SourceFile: "FooDictionary.java"
  Signature: length = 0x2
   00 11 
  minor version: 0
  major version: 50
  Constant pool:
const #1 = class	#2;	//  oss/alphazero/temp/FooDictionary
const #2 = Asciz	oss/alphazero/temp/FooDictionary;
const #3 = class	#4;	//  oss/alphazero/temp/GenericFoo
const #4 = Asciz	oss/alphazero/temp/GenericFoo;
const #5 = Asciz	<init>;
const #6 = Asciz	()V;
const #7 = Asciz	Code;
const #8 = Method	#3.#9;	//  oss/alphazero/temp/GenericFoo."<init>":()V
const #9 = NameAndType	#5:#6;//  "<init>":()V
const #10 = Asciz	LineNumberTable;
const #11 = Asciz	LocalVariableTable;
const #12 = Asciz	this;
const #13 = Asciz	Loss/alphazero/temp/FooDictionary;;
const #14 = Asciz	SourceFile;
const #15 = Asciz	FooDictionary.java;
const #16 = Asciz	Signature;
const #17 = Asciz	Loss/alphazero/temp/GenericFoo<Ljava/lang/String;Ljava/lang/Object;Ljava/util/Map<Ljava/lang/String;Ljava/lang/Object;>;>;;

{
public oss.alphazero.temp.FooDictionary();
  Code:
   Stack=1, Locals=1, Args_size=1
   0:	aload_0
   1:	invokespecial	#8; //Method oss/alphazero/temp/GenericFoo."<init>":()V
   4:	return
  LineNumberTable: 
   line 5: 0

  LocalVariableTable: 
   Start  Length  Slot  Name   Signature
   0      5      0    this       Loss/alphazero/temp/FooDictionary;


}

// ===  usage ===

package oss.alphazero.temp;

import java.util.Map;

public class Main {
	public static void main(String[] args) {
		FooDictionary foodict = new FooDictionary();
		System.out.println(foodict.getClass().getCanonicalName());
		
		GenericFoo<String, Object, Map<String,Object>> genfoo = new GenericFoo<String, Object, Map<String,Object>>();
		System.out.println(genfoo.getClass().getCanonicalName());
	}
}

output:

oss.alphazero.temp.FooDictionary
oss.alphazero.temp.GenericFoo

-- javap --

Compiled from "Main.java"
public class oss.alphazero.temp.Main extends java.lang.Object
  SourceFile: "Main.java"
  minor version: 0
  major version: 50
  Constant pool:
const #1 = class	#2;	//  oss/alphazero/temp/Main
const #2 = Asciz	oss/alphazero/temp/Main;
const #3 = class	#4;	//  java/lang/Object
const #4 = Asciz	java/lang/Object;
const #5 = Asciz	<init>;
const #6 = Asciz	()V;
const #7 = Asciz	Code;
const #8 = Method	#3.#9;	//  java/lang/Object."<init>":()V
const #9 = NameAndType	#5:#6;//  "<init>":()V
const #10 = Asciz	LineNumberTable;
const #11 = Asciz	LocalVariableTable;
const #12 = Asciz	this;
const #13 = Asciz	Loss/alphazero/temp/Main;;
const #14 = Asciz	main;
const #15 = Asciz	([Ljava/lang/String;)V;
const #16 = class	#17;	//  oss/alphazero/temp/FooDictionary
const #17 = Asciz	oss/alphazero/temp/FooDictionary;
const #18 = Method	#16.#9;	//  oss/alphazero/temp/FooDictionary."<init>":()V
const #19 = Field	#20.#22;	//  java/lang/System.out:Ljava/io/PrintStream;
const #20 = class	#21;	//  java/lang/System
const #21 = Asciz	java/lang/System;
const #22 = NameAndType	#23:#24;//  out:Ljava/io/PrintStream;
const #23 = Asciz	out;
const #24 = Asciz	Ljava/io/PrintStream;;
const #25 = Method	#3.#26;	//  java/lang/Object.getClass:()Ljava/lang/Class;
const #26 = NameAndType	#27:#28;//  getClass:()Ljava/lang/Class;
const #27 = Asciz	getClass;
const #28 = Asciz	()Ljava/lang/Class;;
const #29 = Method	#30.#32;	//  java/lang/Class.getCanonicalName:()Ljava/lang/String;
const #30 = class	#31;	//  java/lang/Class
const #31 = Asciz	java/lang/Class;
const #32 = NameAndType	#33:#34;//  getCanonicalName:()Ljava/lang/String;
const #33 = Asciz	getCanonicalName;
const #34 = Asciz	()Ljava/lang/String;;
const #35 = Method	#36.#38;	//  java/io/PrintStream.println:(Ljava/lang/String;)V
const #36 = class	#37;	//  java/io/PrintStream
const #37 = Asciz	java/io/PrintStream;
const #38 = NameAndType	#39:#40;//  println:(Ljava/lang/String;)V
const #39 = Asciz	println;
const #40 = Asciz	(Ljava/lang/String;)V;
const #41 = class	#42;	//  oss/alphazero/temp/GenericFoo
const #42 = Asciz	oss/alphazero/temp/GenericFoo;
const #43 = Method	#41.#9;	//  oss/alphazero/temp/GenericFoo."<init>":()V
const #44 = Asciz	args;
const #45 = Asciz	[Ljava/lang/String;;
const #46 = Asciz	foodict;
const #47 = Asciz	Loss/alphazero/temp/FooDictionary;;
const #48 = Asciz	genfoo;
const #49 = Asciz	Loss/alphazero/temp/GenericFoo;;
const #50 = Asciz	LocalVariableTypeTable;
const #51 = Asciz	Loss/alphazero/temp/GenericFoo<Ljava/lang/String;Ljava/lang/Object;Ljava/util/Map<Ljava/lang/String;Ljava/lang/Object;>;>;;
const #52 = Asciz	SourceFile;
const #53 = Asciz	Main.java;

{
public oss.alphazero.temp.Main();
  Code:
   Stack=1, Locals=1, Args_size=1
   0:	aload_0
   1:	invokespecial	#8; //Method java/lang/Object."<init>":()V
   4:	return
  LineNumberTable: 
   line 5: 0

  LocalVariableTable: 
   Start  Length  Slot  Name   Signature
   0      5      0    this       Loss/alphazero/temp/Main;


public static void main(java.lang.String[]);
  Code:
   Stack=2, Locals=3, Args_size=1
   0:	new	#16; //class oss/alphazero/temp/FooDictionary
   3:	dup
   4:	invokespecial	#18; //Method oss/alphazero/temp/FooDictionary."<init>":()V
   7:	astore_1
   8:	getstatic	#19; //Field java/lang/System.out:Ljava/io/PrintStream;
   11:	aload_1
   12:	invokevirtual	#25; //Method java/lang/Object.getClass:()Ljava/lang/Class;
   15:	invokevirtual	#29; //Method java/lang/Class.getCanonicalName:()Ljava/lang/String;
   18:	invokevirtual	#35; //Method java/io/PrintStream.println:(Ljava/lang/String;)V
   21:	new	#41; //class oss/alphazero/temp/GenericFoo
   24:	dup
   25:	invokespecial	#43; //Method oss/alphazero/temp/GenericFoo."<init>":()V
   28:	astore_2
   29:	getstatic	#19; //Field java/lang/System.out:Ljava/io/PrintStream;
   32:	aload_2
   33:	invokevirtual	#25; //Method java/lang/Object.getClass:()Ljava/lang/Class;
   36:	invokevirtual	#29; //Method java/lang/Class.getCanonicalName:()Ljava/lang/String;
   39:	invokevirtual	#35; //Method java/io/PrintStream.println:(Ljava/lang/String;)V
   42:	return
  LineNumberTable: 
   line 7: 0
   line 8: 8
   line 10: 21
   line 11: 29
   line 12: 42

  LocalVariableTable: 
   Start  Length  Slot  Name   Signature
   0      43      0    args       [Ljava/lang/String;
   8      35      1    foodict       Loss/alphazero/temp/FooDictionary;
   29      14      2    genfoo       Loss/alphazero/temp/GenericFoo;

  LocalVariableTypeTable: length = 0xC
   00 01 00 1D 00 0E 00 30 00 33 00 02 

}