Develop Reference

NL locale returns ambiguous number

if I want to use different number formats across Europe to one format (double), it doesn't seem to work.
Locale locale = new Locale("nl", "NL");
NumberFormat nf= NumberFormat.getNumberInstance(locale);
returns nf.parse("4,000.00").doubleValue();
it returns 4.000 instead of 4000.0, but when enter nf.parse("900,00") it works (returns 900.0)
Another time I enter 4000 and it converts to 4000.0 (expected).
So now I am left with inconsistent types.
I want to convert each number to the same double format. can you guide me?

now I am left with inconsistent types
This is incorrect. The behaviour is entirely consistent and according to spec.
In dutch, the comma is the wholes/fractions separator: There can be only one, and everything to the left is the wholes, and to the right of it, the fractional part. The dot is the thousands separator.
900,00
This is parsed as nine hundred, whole. 900 is to the left of the comma - so those are the wholes. 00 is the fractional part, which is nothing, so, you end up with 900. As expected - a dutch person reading 900,00 would assume that said 'nine hundred'.
4000
Obviously, that's four thousand. No problems there.
4,000.00
That's 4,000 - i.e. four, with 000 as fractional part, and that is how this is parsed. The .00 isn't parsed at all.
Wait, what?
NumberFormat is designed to parse multiple numbers from a stream of text. Even the .parse(string) version of it. Here, try it:
Locale locale = new Locale("nl", "NL");
NumberFormat nf= NumberFormat.getNumberInstance(locale);
System.out.println(nf.parse("4,000hey now this is strange").doubleValue();
works and runs fine, and prints '4'.
Fixing it
If you really want to fix it, you have a few strategies. One of them, is to first verify that the entire input is valid (e.g. with a regular expression) and only then parsing it.
Another option is to explicitly check that the whole input is consumed. You can do that:
String input = "4,000.00";
ParsePosition ps = new ParsePosition(0);
Locale locale = new Locale("nl", "NL");
NumberFormat nf = NumberFormat.getNumberInstance(locale);
double v = nf.parse(input, ps).doubleValue();
if (ps.getIndex() != input.length()) throw new IllegalArgumentException("Not a number: " + input);
The above code parses 900,00 as nine hundred, parser 4000 as four thousand, same for 4.000, and throws an exception if you attempt to toss 4,000.00 at it. Which is, indeed, not a valid anything in dutch locale.
I want something that parses both 4,000.00 as 4000, but also 900,00 as 900.
That is highly inconsistent and implies you want 4,000 to be parsed as 4 and yet 4,000.00 as 4000. If you want this, you're on your own and have to write it from scratch, no built in library (or, as far as I know, any external one) would do such utter befuddled inconsistent craziness.
NB: Note that the snippet would parse 4.000.00 as 400000 and works fine; inconsistent application of thousands separators is leniently parsed by NumberFormat and you can't tell it to be strict. In fact, 4.1.23.4567 is parsed as 41234567 - the only reason 4,000.00 is not parsed in the first place is because dots are not allowed in the fractional part at all. If you don't want that, you're again stuck, you can't use NumberFormat then. Regexes maybe, but you're now on the hook for writing one for each locale you care to support.

Java to C# format specifiers

I am new to C# having used Java.
I am looking to output an expression of 4.5 - 2.7... In Java I would simply write System.out.format("%.2f\n", 4.5 - 2.7);
In C#, I have used Console.WriteLine(4.5 - 2.7); but I am looking to print 2 decimal places.
Could someone be so kind as to explain how I achieve this?

Use String.Format (Link To Documentation)
Use the format {Parameter Number:Decimal Places}
Console.WriteLine(String.Format(" We are going to format 15.6345 as {0:0.00}",15.6345));
Test it here!.
Good luck!
EDIT / Clarification
By Parameter Number, String.Format takes all other inputs after the first input of a string to be values to format and place into the string.
Every time {x:yyz} appears in the string, System.String.Format will format x in the style yyz, where x is the index of the value passed in.
In my example above, 15.6345 is x, and the format 0.00 is yyz.
You could format 2 numbers or repeat one by going:
Console.WriteLine(String.Format(" We are going to format 15.6345 as {0:0.00} , the format 3.123 as 3.1 {1:0.0} , then repeat 15.6345 as 15.6 {0:0.0}",15.6345,3.123));

Translate Hexadecimal transformation from Oracle SQL into Java code

In searching for an answer, I used the solution provided in the following link : How to format a Java string with leading zero?
I have the following code that needs to be translated into java:
TRIM(TO_CHAR(123,'000X'))
From what I can tell, it translates the number into hexa and adds some leading zeros.
However, if I give a big value, I get ##### as answer, e.g. for the following code:
TRIM(TO_CHAR(999999,'000X'))
In Java, my current solution is the following:
String numberAsHex = Integer.toHexString(123);
System.out.println(("0000" + numberAsHex).substring(numberAsHex.length()));
It works fine for small numbers, but for big ones, like 999999 it outputs 423f. So it does the transformation, resulting the value f423f and then it cuts a part off. So I am nowhere near the value from Oracle
Any suggestion as to how to do this? Or why are ##### displayed in the Oracle case?

Instead of Integer.toHexString I would recommend using String.format because of its greater flexibility.
int number = ...;
String numberAsHex = String.format("%06x", number);
The 06 means you get 6 digits with leading zeros, x means you get lowercase hexadecimal.
Examples:
for number = 123 you get numberAsHex = "00007b"
for number = 999999you get numberAsHex = "0f423f"

JavaScript formatting time 24hours format to 12hours

I was having some trouble when trying to format time in 24 hours format to 12 hours format. Here are some of the example of my time in string format:
0:00, 9:00, 12:00, 15:00
I wonder how should I substr the first two character in JavaScript because some of them were one digit and some were two. The output time format should be in 12 hours format like:
12:00AM, 9:00AM, 12:00PM, 3:00PM
Any guides? Thanks in advance.

In comments you clarified that each string you process will have only a single time in it (i.e., you are not processing a single string with four comma-separated times in it). So essentially you have input as follows:
var input = "9:00";
The easiest way to extract the hour and minute is using the String .split() method. This splits up the string at a specified character - in your case you'd use ":" - and returns an array with the pieces:
var parts = input.split(":"),
hour = parts[0],
minute = parts[1];

The obvious answer would be to use regular expressions (but remember AWZ's rule: if you have a problem and decide it can be solved with RE's, then you now have two prolems).
However, save yourself a whole helluva lot of trouble and get moment.js

What is the best way for converting phone numbers into international format (E.164) using Java?

What is the best way for converting phone numbers into international format (E.164) using Java?
Given a 'phone number' and a country id (let's say an ISO country code), I would like to convert it into a standard E.164 international format phone number.
I am sure I can do it by hand quite easily - but I would not be sure it would work correctly in all situations.
Which Java framework/library/utility would you recommend to accomplish this?
P.S. The 'phone number' could be anything identifiable by the general public - such as
* (510) 786-0404
* 1-800-GOT-MILK
* +44-(0)800-7310658
that last one is my favourite - it is how some people write their number in the UK and means that you should either use the +44 or you should use the 0.
The E.164 format number should be all numeric, and use the full international country code (e.g.+44)

Google provides a library for working with phone numbers. The same one they use for Android
http://code.google.com/p/libphonenumber/
String swissNumberStr = "044 668 18 00"
PhoneNumberUtil phoneUtil = PhoneNumberUtil.getInstance();
try {
PhoneNumber swissNumberProto = phoneUtil.parse(swissNumberStr, "CH");
} catch (NumberParseException e) {
System.err.println("NumberParseException was thrown: " + e.toString());
}
// Produces "+41 44 668 18 00"
System.out.println(phoneUtil.format(swissNumberProto, PhoneNumberFormat.INTERNATIONAL));
// Produces "044 668 18 00"
System.out.println(phoneUtil.format(swissNumberProto, PhoneNumberFormat.NATIONAL));
// Produces "+41446681800"
System.out.println(phoneUtil.format(swissNumberProto, PhoneNumberFormat.E164));

Speaking from experience at writing this kind of thing, it's really difficult to do with 100% reliability. I've written some Java code to do this that is reasonably good at processing the data we have but won't be applicable in every country. Questions you need to ask are:
Are the character to number mappings consistent between countries? The US uses a lot of this (eg 1800-GOT-MILK) but in Australia, as one example, its pretty rare. What you'd need to do is ensure that you were doing the correct mapping for the country in question if it varies (it might not). I don't know what countries that use different alphabets (eg Cyrilic in Russia and the former Eastern block countries) do;
You have to accept that your solution will not be 100% and you should not expect it to be. You need to take a "best guess" approach. For example, theres no real way of knowing that 132345 is a valid phone number in Australia, as is 1300 123 456 but that these are the only two patterns that are for 13xx numbers and they're not callable from overseas;
You also have to ask if you want to validate regions (area codes). I believe the US uses a system where the second digit of the area code is a 1 or a 0. This may have once been the case but I'm not sure if it still applies. Whatever the case, many other countries will have other rules. In Australia, the valid area codes for landlines and mobile (cell) phones are two digits (the first is 0). 08, 03 and 04 are all valid. 01 isn't. How do you cater for that? Do you want to?
Countries use different conventions no matter how many digits they're writing. You have to decide if you want to accept something other than the "norm". These are all common in Australia:
(02) 1234 5678
02 1234 5678
0411 123 123 (but I've never seen 04 1112 3456)
131 123
13 1123
131 123
1 300 123 123
1300 123 123
02-1234-5678
1300-234-234
+44 78 1234 1234
+44 (0)78 1234 1234
+44-78-1234-1234
+44-(0)78-1234-1234
0011 44 78 1234 1234 (0011 is the standard international dialling code)
(44) 078 1234 1234 (not common)
And thats just off the top of my head. For one country. In France, for example, its common the write the phone number in number pairs (12 34 56 78) and they pronounce it that way too: instead of:
un (one), deux (two), trois (three), ...
its
douze (twelve), trente-quatre (thirty four), ...
Do you want to cater for that level of cultural difference? I would assume not but the question is worth considering just in case you make your rules too strict.
Also some people may append extension numbers on phone numbers, possibly with "ext" or similar abbreviation. Do you want to cater for that?
Sorry, no code here. Just a list of questions to ask yourself and issues to consider. As others have said, a series of regular expressions can do much of the above but ultimately phone number fields are (mostly) free form text at the end of the day.

This was my solution:
public static String FixPhoneNumber(Context ctx, String rawNumber)
{
String fixedNumber = "";
// get current location iso code
TelephonyManager telMgr = (TelephonyManager) ctx.getSystemService(Context.TELEPHONY_SERVICE);
String curLocale = telMgr.getNetworkCountryIso().toUpperCase();
PhoneNumberUtil phoneUtil = PhoneNumberUtil.getInstance();
Phonenumber.PhoneNumber phoneNumberProto;
// gets the international dialling code for our current location
String curDCode = String.format("%d", phoneUtil.getCountryCodeForRegion(curLocale));
String ourDCode = "";
if(rawNumber.indexOf("+") == 0)
{
int bIndex = rawNumber.indexOf("(");
int hIndex = rawNumber.indexOf("-");
int eIndex = rawNumber.indexOf(" ");
if(bIndex != -1)
{
ourDCode = rawNumber.substring(1, bIndex);
}
else if(hIndex != -1)
{
ourDCode = rawNumber.substring(1, hIndex);
}
else if(eIndex != -1)
{
ourDCode = rawNumber.substring(1, eIndex);
}
else
{
ourDCode = curDCode;
}
}
else
{
ourDCode = curDCode;
}
try
{
phoneNumberProto = phoneUtil.parse(rawNumber, curLocale);
}
catch (NumberParseException e)
{
return rawNumber;
}
if(curDCode.compareTo(ourDCode) == 0)
fixedNumber = phoneUtil.format(phoneNumberProto, PhoneNumberFormat.NATIONAL);
else
fixedNumber = phoneUtil.format(phoneNumberProto, PhoneNumberFormat.INTERNATIONAL);
return fixedNumber.replace(" ", "");
}
I hope this helps someone with the same problem.
Enjoy and use freely.

Thanks for the answers. As stated in the original question, I am much more interested in the formatting of the number into the standard format than I am in determining if it is a valid (as in genuine) phone number.
I have some hand crafted code currently that takes a phone number String (as entered by the user) and a source country context and target country context (the country from where the number is being dialed, and the country to where the number is being dialed - this is known to the system) and then does the following conversion in steps
Strip all whitespace from the number
Translate all alpha into digits - using a lookup table of letter to digit (e.g. A-->2, B-->2, C-->2, D-->3) etc. for the keypad (I was not aware that some keypads distribute these differently)
Strip all punctuation - keeping a preceding '+' intact if it exists (in case the number is already in some sort of international format).
Determine if the number has an international dialling prefix for the country context - e.g. if source context is the UK, I would see if it starts with a '00' - and replace it with a '+'. I do not currently check whether the digits following the '00' are followed by the international dialing code for the target country. I look up the international dialing prefix for the source country in a lookup table (e.g. GB-->'00', US-->'011' etc.)
Determine if the number has a local dialing prefix for the country context - e.g. if the source context is the UK, I would look to see if it starts with a '0' - and replace it with a '+' followed by the international dialing code for the target country. I look up the local dialing prefix for the source country in a lookup table (e.g. GB-->'0', US-->'1' etc.), and the international dialing code for the target country in another lookup table (e.g.'GB'='44', US='1')
It seems to work for everything I have thrown at it so far - except for the +44(0)1234-567-890 situation - I will add a special case check for that one.
Writing it was not hard - and I can add special cases for each strange exception I come across. But I would really like to know if there is a standard solution.
The phone companies seem to deal with this thing every day. I never get inconsistent results when dialing numbers using the PSTN. For example, in the US (where mobile phones have the same area codes as landlines, I could dial +1-123-456-7890, or 011-1-123-456-7890 (where 011 is the international dialing prefix in the US and 1 is the international dialing code for the US), 1-123-456-7890 (where 1 is the local dialing prefix in the US) or even 456-7890 (assuming I was in the 123 area code at the time) and get the same results each time. I assume that internally these dialed numbers get converted to the same E.164 standard format, and that the conversion is all done in software.

To be honest, it sounds like you've got most of the bases covered already.
The +44(0)800 format sometimes (incorrectly) used in the UK is annoying and isn't strictly valid according to E.123, which is the ITU-T recommendation for how numbers should be displayed. If you haven't got a copy of E.123 it's worth a look.
For what it's worth, the telephone network itself doesn't always use E.164. Often there'll be a flag in the ISDN signalling generated by the PBX (or in the network if you're on a steam phone) which tells the network whether the number being dialled is local, national or international.

In some countries you can validate 112 as a valid phone number, but if you stick a country code in front of it it won't be valid any more. In other countries you can't validate 112 but you can validate 911 as a valid phone number.
I've seen some phones that put Q on the 7 key and Z on the 9 key. I've seen some phones that put Q and Z on the 0 key, and some that put Q and Z on the 1 key.
An area code that existed yesterday might not exist today, and vice-versa.
In half of North America (country code 1), the second digit rule used to be 0 or 1 for area codes, but that rule went away 10 years ago.

I'm not aware of a standard library or framework available for formatting telephone numbers into E.164.
The solution used for our product, which requires formatting PBX provided caller-id into E.164, is to deploy a file (database table) containing the E.164 format information for all countries applicable.
This has the advantage that the application can be updated (to handle all the strange corner cases in various PSTN networks) w/out requiring changes to the production code base.
The table contains a row for each country code and information regarding area code length and subscriber length. There may be multiple entries for a country depending on what variations are possible with area code and subscriber number lengths.
Using New Zealand PSTN (partial) dial plan as an example of the table..
CC AREA_CODE AREA_CODE_LENGTH SUBSCRIBER SUBSCRIBER_LENGTH
64 1 7
64 21 2 7
64 275 3 6
We do something similar to what you have described, i.e. strip the provided telephone number of any non-digit characters and then format based on various rules regarding overall number plan length, outside access code, and long distance/international access codes.