Java VMと戯れてみる
J2SE 5.0の新機能
wikipedia:Java仮想マシン
言語仕様の限界にチャレンジする前に，言語使用と仲の悪くない実装を考えないと．
…ということで，とりあえずテスト．
public class CastTest<E> { public Object i; public CastTest(E i) { this.i = i; } public void setI(E i) { this.i = i; } @SuppressWarnings("unchecked") public E getI() { return (E)i; } public static void main(String[] args) { Integer i0 = Integer.valueOf(1); Integer i1 = Integer.valueOf(100); Integer i2 = Integer.valueOf(10000); Integer i3 = Integer.valueOf(10000000); CastTest ct = new CastTest<Integer>(i0); System.out.println(ct.i); System.out.println(ct.getI()); } }
で，これをjavacしてjavap -c．
Compiled from "CastTest.java"
public class CastTest extends java.lang.Object{
public java.lang.Object i;
public CastTest(java.lang.Object);
Code:
0: aload_0
1: invokespecial #1; //Method java/lang/Object."<init>":()V
4: aload_0
5: aload_1
6: putfield #2; //Field i:Ljava/lang/Object;
9: return
public void setI(java.lang.Object);
Code:
0: aload_0
1: aload_1
2: putfield #2; //Field i:Ljava/lang/Object;
5: return
public java.lang.Object getI();
Code:
0: aload_0
1: getfield #2; //Field i:Ljava/lang/Object;
4: areturn
public static void main(java.lang.String[]);
Code:
0: iconst_1
1: invokestatic #3; //Method java/lang/Integer.valueOf:(I)Ljava/lang/Integer;
4: astore_1
5: bipush 100
7: invokestatic #3; //Method java/lang/Integer.valueOf:(I)Ljava/lang/Integer;
10: astore_2
11: sipush 10000
14: invokestatic #3; //Method java/lang/Integer.valueOf:(I)Ljava/lang/Integer;
17: astore_3
18: ldc #4; //int 10000000
20: invokestatic #3; //Method java/lang/Integer.valueOf:(I)Ljava/lang/Integer;
23: astore 4
25: new #5; //class CastTest
28: dup
29: aload_1
30: invokespecial #6; //Method "<init>":(Ljava/lang/Object;)V
33: astore 5
35: getstatic #7; //Field java/lang/System.out:Ljava/io/PrintStream;
38: aload 5
40: getfield #2; //Field i:Ljava/lang/Object;
43: invokevirtual #8; //Method java/io/PrintStream.println:(Ljava/lang/Object;)V
46: getstatic #7; //Field java/lang/System.out:Ljava/io/PrintStream;
49: aload 5
51: invokevirtual #9; //Method getI:()Ljava/lang/Object;
54: invokevirtual #8; //Method java/io/PrintStream.println:(Ljava/lang/Object;)V
57: return
}
