Insert Comma?

2010-01-06

no one:
I think it's worth noting that in Java the plus operator actually uses a StringBuffer behind the scenes anyway, so constructing your own in this simple case just adds needless wordiness.
Also, I hate these terrible catch blocks. Do you really want to return an empty string when there's an error? REALLY??

Not only does using a StringBuffer yourself result in needless wordiness, it also generates more bytecode. If you use String concatenation over a StringBuilder, it'll be simpler:

public class Test {
  public static void main(String arg[]) {
    System.out.println(methodA("test"));
    System.out.println(methodB("test"));
  }
  public static String methodA(String s) {
    StringBuilder sb = new StringBuilder();
    char c = '"';
    sb.append(c);
    sb.append(s);
    sb.append(c);
    return sb.toString();
  }
  public static String methodB(String s) {
    return '"' + s + '"';
  }
}

public static java.lang.String methodA(java.lang.String);
  Code:
   Stack=2, Locals=3, Args_size=1
   0:	new	#7; //class java/lang/StringBuilder
   3:	dup
   4:	invokespecial	#8; //Method java/lang/StringBuilder."<init>":()V
   7:	astore_1
   8:	bipush	34
   10:	istore_2
   11:	aload_1
   12:	iload_2
   13:	invokevirtual	#9; //Method java/lang/StringBuilder.append:(C)Ljava/lang/StringBuilder;
   16:	pop
   17:	aload_1
   18:	aload_0
   19:	invokevirtual	#10; //Method java/lang/StringBuilder.append:(Ljava/lang/String;)Ljava/lang/StringBuilder;
   22:	pop
   23:	aload_1
   24:	iload_2
   25:	invokevirtual	#9; //Method java/lang/StringBuilder.append:(C)Ljava/lang/StringBuilder;
   28:	pop
   29:	aload_1
   30:	invokevirtual	#11; //Method java/lang/StringBuilder.toString:()Ljava/lang/String;
   33:	areturn

public static java.lang.String methodB(java.lang.String);
  Code:
   Stack=2, Locals=1, Args_size=1
   0:	new	#7; //class java/lang/StringBuilder
   3:	dup
   4:	invokespecial	#8; //Method java/lang/StringBuilder."<init>":()V
   7:	bipush	34
   9:	invokevirtual	#9; //Method java/lang/StringBuilder.append:(C)Ljava/lang/StringBuilder;
   12:	aload_0
   13:	invokevirtual	#10; //Method java/lang/StringBuilder.append:(Ljava/lang/String;)Ljava/lang/StringBuilder;
   16:	bipush	34
   18:	invokevirtual	#9; //Method java/lang/StringBuilder.append:(C)Ljava/lang/StringBuilder;
   21:	invokevirtual	#11; //Method java/lang/StringBuilder.toString:()Ljava/lang/String;
   24:	areturn

I realize the code isn't the same in both examples, I took the original method and changed it to what I would probably write (if I wrote something like that).

As for returning an empty String if a RuntimeException occurs: If a RuntimeException occurs when you're prepending and appending quotation marks to a String, you probably shouldn't continue as if nothing is wrong. Letting that RuntimeException bubble up to someplace you can actually do something about it, like displaying "Fatal error, program can not continue" to the user would be better. This assumes you can even do that. Once a RuntimeException has occurred, it's unlikely you will be successful trying to build a message and dialog box to display to the user.

Insert Comma?

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