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NumberFormat

An instance of NumberFormat should be used to parse (and eventually format) numbers in a localized manner:

var locale = Locale.of("de", "DE"); // Locale.FRANCE, Locale.UK, Locale.ROOT, ...
var format = NumberFormat.getIntegerInstance(locale); // getIntegerInstance() for default
int i = format.parse("1234").intValue(); // parse() returns a Number instance (Long)

Localized

That means that Locale specific decimal point, thousands-separator, and even digits will be parsed and used for formatting.
For integer parsing, as asked:

• thousands-separators are ignored;
• decimal point and decimal values are discarded for integer formatters, but used by the other formatters (e.g. getNumberInstance(), getPercentInstance(), ...)
• Unicode digits are accepted

Example:

int i;
NumberFormat format;
format = NumberFormat.getIntegerInstance(Locale.ROOT);
i = format.parse("123,456.789").intValue(); // i = 123456
i = format.parse("١٢٣٤").intValue(); // i = 1234
format = NumberFormat.getIntegerInstance(Locale.GERMANY);
i = format.parse("123.456,789").intValue(); // i = 123456 - note: changed separators
i = format.parse("١٢٣٤").intValue(); // i = 1234

Formatting with NumberFormat will use the digits as specified by the given Locale (if supported):

var locale = Locale.forLanguageTag("jv-ID-u-nu-java");
var formatter = NumberFormat.getIntegerInstance(locale);
var str = formatter.format(123456); // "꧑꧒꧓,꧔꧕꧖"
locale = Locale.forLanguageTag("th-TH-u-nu-thai");
// = new Locale.Builder().setUnicodeLocaleKeyword("nu", "thai").build(); // alternative
formatter = NumberFormat.getIntegerInstance(locale);
str = formatter.format(123456); // "๑๒๓,๔๕๖"

Leniency

NumberFormat, by default, is set to parse leniently. This will hide eventual errors in the input string. Use setStrict(true) to change this behaviour if needed.

var format = NumberFormat.getIntegerInstance(Locale.ROOT);
format.parse("123xyz456"); // just 123
format.setStrict(true);
format.parse("123xyz456"); // throws ParseException

Please refer to the documentation of NumberFormat, Locale and related classes for more details.