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Java postfix delimiters

It's necessary to use a postfix delimiter to denote the type of constant being used in the source code, like L for long. However, for shorts and bytes there are no delimiters, so I need to explicitly cast the constant value like so:

short x = (short)0x8000;

I was wondering if Java takes extra steps in the compiled bytecode to actually convert this from an integer type to a short, or does it know that this will fit into a word and use the constant as is? Otherwise, is there a way I can postfix numbers like these to denote short or byte?

like image 397
William the Coderer Avatar asked Nov 18 '11 03:11

William the Coderer


1 Answers

I was wondering if Java takes extra steps in the compiled bytecode to actually convert this from an integer type to a short, or does it know that this will fit into a word and use the constant as is?

I think it knows that it will fit into a word and uses it as is. For instance bytecode for:

public class IntToShortByteCode {
   public static void main(String... args){
        short x = (short)0x8888;
        System.out.println(x);
    }
}

is (javac 1.6.0_14):

Compiled from "IntToShortByteCode.java"
public class IntToShortByteCode extends java.lang.Object{
public IntToShortByteCode();
  Code:
   0:   aload_0
   1:   invokespecial   #1; //Method java/lang/Object."<init>":()V
   4:   return

public static void main(java.lang.String[]);
  Code:
   0:   sipush  -30584
   3:   istore_1
   4:   getstatic       #2; //Field java/lang/System.out:Ljava/io/PrintStream;
   7:   iload_1
   8:   invokevirtual   #3; //Method java/io/PrintStream.println:(I)V
   11:  return

}

Otherwise, is there a way I can postfix numbers like these to denote short or byte?

No.

like image 192
Alex Nikolaenkov Avatar answered Nov 07 '22 01:11

Alex Nikolaenkov