I need your help to turn a String like 12345678 into 1234.56.78
[FOUR DIGITS].[TWO DIGITS].[TWO DIGITS]
My code:
String s1 = "12345678";
s1 = s1.replaceAll("(\\d{4})(\\d+)", "$1.$2").replaceAll("(\\d{2})(\\d+)", "$1.$2");
System.out.println(s1);
But the result is 12.34.56.78
If you are sure that you'll always have the input in the same format then you can simply use a StringBuilder and do something like this:
String input = "12345678";
String output = new StringBuilder().append(input.substring(0, 4))
.append(".").append(input.substring(4, 6)).append(".")
.append(input.substring(6)).toString();
System.out.println(output);
This code creates a new String by appending the dots to the sub-strings at the specified locations.
Output:
1234.56.78
+ for the concatenation and it will be optimized later by the compiler then it's true. But it's even better if you take care of things yourself rather than leaving it on the compiler. Well, that's my opinion which might differ from what other people think.Use a single replaceAll() method with updated regex otherwise the second replaceAll() call will replace including the first four digits.
System.out.println(s1.replaceAll("(\\d{4})(\\d{2})(\\d+)", "$1.$2.$3")
This puts dots after every pair of chars, except the first pair:
str = str.replaceAll("(^....)|(..)", "$1$2.");
This works for any length string, including odd lengths.
For example
"1234567890123" --> "1234.56.78.90.12.3"