Format for the default locale : NumberFormat « I18N « Java Tutorial

1. Java Tutorial
2. I18N
3. NumberFormat

import java.text.NumberFormat;

public class Main {
  public static void main(String[] argv) throws Exception {

    String string = NumberFormat.getNumberInstance().format(-1234.56);
    System.out.println(string);
  }
}
//-1,234.56