C:\temp\test>javap -c Test
Compiled from "Test.java"
public class Test extends java.lang.Object{
public Test();
Code:
0: aload_0
1: invokespecial #1; //Method java/lang/Object."<init>":()V
4: return

public static void main(java.lang.String[]);
Code:
0: iconst_0
1: istore_1
2: bipush 31
4: istore_1
5: getstatic #2; //Field java/lang/System.out:Ljava/io/PrintStream;
8: iload_1
9: invokevirtual #3; //Method java/io/PrintStream.println:(I)V
12: return

}
ちゃんと値に置き換えてるように見えるけど。