Page Comparison

String Built-in Functions

These built-in functions are accessed via the pseudo unit “String”

String:concat

Returns a string value that is the concatenated result of two or more arguments passed to the function. As of Helium 1.3.1 null values will be treated as empty strings.

Info
@Test void testConcatenate(){ Assert:isEqual("abcdef", String:concat("abc","def"), "Concatenate returned an incorrect string"); Assert:isEqual("abcdef", String:concat("abc",null,"def"), "Concatenate returned an incorrect string"); }

String:split

Returns an array of string values that represent the tokens from the value expression that are separated by the separator expression.

Note that in order to split a special character such as '|', one needs to escape the string with a '\' character. The '\' may need to be escaped as well, so in this case one will end up with String:split(someText, "\\|").

Info
@Test void testSplit(){ string[] result = String:split("abc def", " "); Assert:isEqual(2, result.length(), "Split returned an incorrect number of tokens"); Assert:isEqual(result.get(0), "abc", "Split returned an incorrect first token"); Assert:isEqual(result.get(1), "def", "Split returned an incorrect second token"); }

String:length

Returns the length of the string being passed

Info
int i = String:length("Hello world");

String:substring

Substring of a string based on index positions

Info
@Test void testSubstring(){ Assert:isEqual("ello", String:substring("Hello World", 1, 4), "String:substring failed"); Assert:isNotEqual("ello", String:substring("Hello World", 1, 3), "String:substring failed"); }

String:lower

Convert string to lowercase

Info
@Test void testLower(){ Assert:isEqual("hello world", String:lower("Hello World"), "String:lower failed"); Assert:isNotEqual("Hello world", String:lower("Hello World"), "String:lower failed"); }

String:upper

Convert string to uppercase

Info
@Test void testUpper() { Assert:isEqual("HELLO WORLD", String:upper("hello world"), "String:upper failed"); Assert:isNotEqual("hello world", String:upper("hello world"), "String:upper failed"); }

String:startsWith

Check if a particular string starts with a string

Info
@Test void testStartsWith(){ Assert:isTrue(String:startsWith("Hello World", "Hello"), "String:startsWith failed"); Assert:isFalse(String:startsWith("Hello World", "ello"), "String:startsWith failed"); }

String:endsWith

Check if a particular string ends with a string

Info
@Test void testEndsWith(){ Assert:isTrue(String:endsWith("Hello World", "World"), "String:endsWith failed"); Assert:isFalse(String:endsWith("Hello World", "Worl"), "String:endsWith failed"); }

String:indexOf

Returns the index within this string of the first occurrence of the specified substring.

Info
@Test void testIndexOf(){ Assert:isEqual(0, String:indexOf("Hello World", "Hello"), "String:indexOf failed"); Assert:isEqual(1, String:indexOf("Hello World", "ello "), "String:indexOf failed"); Assert:isEqual(2, String:indexOf("Hello World", "llo W"), "String:indexOf failed"); Assert:isEqual(3, String:indexOf("Hello World", "lo Wo"), "String:indexOf failed"); }

String:join

Join a collection of strings into one result string with the specified join character

Info
@Test void testJoin(){ string original = "abc def ghi"; string separator = " "; Assert:isEqual(original, String:join(String:split(original, separator), separator), "String:join failed"); }

String Functions

These are built-in functions available on the String namespace.

`concat`

Returns a string value that is the concatenated result of two or more arguments passed to the function. Null values are treated as empty strings.

Code Block
string s = String:concat("abc","def");

`split`

Returns an array of string values that represent the tokens from the value expression that are separated by the separator expression.

Note that in order to split a special character such as '|', one needs to escape the string with a '\' character. The '\' may need to be escaped as well, so in this case one will end up with String:split(someText, "\\|").

Code Block
string[] result = String:split("abc def", " "); string first = result.get(0); //first = "abc" string second = result.get(1); //second = "def"

`length`

Returns the length of the string argument.

Code Block
int i = String:length("Hello world");

`substring`

Substring of a string based on index positions.

Code Block
string s = String:substring("Hello World", 1, 4); //s = "ello"

`lower`

Convert string to lowercase.

Code Block
string s = String:lower("Hello World"); //s = "hello world"

`upper`

Convert string to uppercase.

Code Block
string s = String:upper("Hello World"); //s = "HELLO WORLD"

`startsWith`

Check if the beginning part of a string matches another string.

Code Block
bool b = String:startsWith("Hello World", "Hello"); //b = true

`endsWith`

Check if the ending part of a string matches another string.

Code Block
bool b = String:endsWith("Hello World", "World"); //b = true

`indexOf`

Returns the index within this string of the first occurrence of the specified substring.

Code Block
int i = String:indexOf("Hello World", "llo W"); //i = 2

If the second string argument cannot be found within the first, a value of null is returned.

`join`

Joins a collection of strings into one result string with the specified join character.

Code Block
string[] strings; strings.append("abc"); strings.append("def"); string s = String:join(strings, " "); //s = "abc def"

`translate`

Fetches the translation from the lang file using the argument as key.

Code Block

language	text
title	en.lang

message.default_warning = You've been warned.

Code Block
string s = String:translate("message.default_warning"); //s = "You've been warned."

`regexMatch`

Compares a string with a regular expression and returns (boolean) true if it matches.

Code Block

language	java

if (String:regexMatch("27000111abc","^27[0-9]{9,}$") == false) {
	Mez:alertError("alert.invalid.phonenum");
}

The behaviour of the regexMatch in Helium is consistent with that of the java.util.regex implementation, so it is advised to consult the java.util.regex JavaDoc when troubleshooting. Take particular note of the following:

Backslashes within string literals in Java source code are interpreted as required by The Java™ Language Specification as either Unicode escapes (section 3.3) or other character escapes (section 3.10.6) It is therefore necessary to double backslashes in string literals that represent regular expressions to protect them from interpretation by the Java bytecode compiler. The string literal "\b", for example, matches a single backspace character when interpreted as a regular expression, while "\\b" matches a word boundary. The string literal "\(hello\)" is illegal and leads to a compile-time error; in order to match the string (hello) the string literal "\\(hello\\)" must be used.

This means, for example, that while online regex validators will accept a curly bracket escaped by a single backslash as valid, it need to be escaped with a double backslash in the DSL. For example:

Code Block
bool b = String:regexMatch("trying {out} regex", ".\\{out\\}."); //true

Another example is when attempting to using the literal period ('.'). In such case, since period is a metacharacter representing wild card matches, it will need to be "double escaped" when used in a regular expression match in the DSL.

`regexReplaceFirst`

Matches a regex within a source string and replaces the first match with a replacement value.

Note that the same rules as mentioned before regarding escaping of characters applies here.

Code Block
string result = String:regexReplaceFirst("ab32c56desd111", "[0-9]", "X"); //abX2c56desd111

`regexReplaceAll`

Matches a regex within a source string and replaces all matches with a replacement value.

Note that the same rules as mentioned before regarding escaping of characters applies here.

Code Block
string result = String:regexReplaceAll("ab32c56desd111", "[0-9]", "X"); //abXXcXXdesdXXX

`replaceAll`

Matches a value within a source string and replaces all matches with a replacement value.

Code Block
string result = String:replaceAll("Hello World", "l", "L"); //HeLLo WorLd

`urlEncode`

Encodes the given argument into the HTML form encoding (UTF-8).

Code Block

language	java

string encodedNames = String:urlEncode("First Last Names");
// encodedNames = First+Last+Names

string encodedTest = String:urlEncode("The string ü@foo-bar");
// encodedTest = The+string+%C3%BC%40foo-bar

Helium will always encode the given argument into the UTF-8 format. The following rules apply to the encoding:

The alphanumeric characters "a" through "z", "A" through "Z" and "0" through "9" remain the same.
The special characters ".", "-", "*", and "_" remain the same.
The space character " " is converted into a plus sign "+".
All other characters are unsafe and are first converted into one or more bytes using some encoding scheme. Then each byte is represented by the 3-character string "%xy", where xy is the two-digit hexadecimal representation of the byte.

Versions Compared

Old Version 7

New Version Current

Key

String Built-in Functions

String:concat

String:split

String:length

String:substring

String:lower

String:upper

String:startsWith

String:endsWith

String:indexOf

String:join

String:translate

Additional Mentions and References

String Functions

`concat`

`split`

`length`

`substring`

`lower`

`upper`

`startsWith`

`endsWith`

`indexOf`

`join`

`translate`

`regexMatch`

`regexReplaceFirst`

`regexReplaceAll`

`replaceAll`

`urlEncode`

Additional Mentions and References