Is this a good way of clearing a StringBuilder?

Question

I would just like to ask if this is a good way of clearing/emptying a StringBuilder? It is wrapped in a method and it is called several times, is this thread safe? Does this not consume a lot of memory? Would it be better if I created the StringBuilder outside of the method and in the class instead?

private void callMe(){
    StringBuilder builder = new StringBuilder();
    builder.delete(0, builder.length());
}

builder.append("some ID");

if (builder.toString().contains("some other ID"))
    Show("Information")
else
    Show("Invalid ID")

Why after you create a new object, you `builder.delete(0, builder.length());`? — Maroun, May 12 '15 at 11:32
This is just part of the whole code, it's used to compare a string with it after appending it with an ID from the web service. I clear it since it's called several times. — Hiroga Katageri, May 12 '15 at 11:33
This part of your whole code does not interact with other parts of your code. — stevecross, May 12 '15 at 11:35

score 3 · Answer 1 · answered May 12 '15 at 11:36

3

It would be more efficient to call

sb.setLength(0);

Because that's only one method call, instead of two.

answered May 12 '15 at 11:36

Elliott Frisch

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score 2 · Accepted Answer · answered May 12 '15 at 11:37

Before I post my answer I am assuming that you are using StringBuilder in a loop and every few iterations you may want to empty it and start with an empty StringBuilder. In that case I can think of two approaches:

invoke setLength(0) on the string builder you are using. I prefer this over delete as I feel this is more neat.
Or allocate a new one instead rather than clearing the buffer. It may not be an ideal option but still an option.

Is this a good way of clearing a StringBuilder?

2 Answers2