Java 13 - Text Blocks (JEP 355)
Text blocks allows us to create multiline strings easily. It allow a better way of writing, and more importantly reading, multi-line text inside Java code. The multiline string has to be written inside a pair of triple-double quotes.
This feature allow us to write code from other languages inside our Java code. Previously, you would always need boilerplate like /n for line breaks at the end of every line, which makes code error-prone and hard to read. Here example to build strings for HTML, JSON, and SQL:
JEP355TextBlocks.java
public class JEP355TextBlocks {
public static void main(String[] args) {
// text blocks for html
String html = """
<html>
<body>
<p>Hello, fellow programmers</p>
</body>
</html>
""";
System.out.println(html);
// text blocks for json
String json = """
{
"firstName": "Regina",
"lastName": "Poetri",
"age": 20
}
""";
System.out.println(json);
// text blocks for sql
String sql = """
SELECT FIRST_NAME, LAST_NAME, BIRTH_DATE
FROM CUSTOMER
WHERE CUSTOMER_ID = ?
""";
System.out.println(sql);
}
}
And when we run it:
<html> <body> <p>Hello, fellow programmers</p> </body> </html> { "firstName": "Regina", "lastName": "Poetri", "age": 20 } SELECT FIRST_NAME, LAST_NAME, BIRTH_DATE FROM CUSTOMER WHERE CUSTOMER_ID = ?
We can use this feature for any "Polyglot" language inside our Java code. This is better than concat String that we always use before:
String sql = "SELECT FIRST_NAME, LAST_NAME, BIRTH_DATE\n" +
"FROM CUSTOMER\n" +
"WHERE CUSTOMER_ID = ?\n";
This feature is still a preview feature in Java 13.
New Methods in String Class for Text Blocks
There are three new methods in the String class, associated with the text blocks feature:
- String formatted(Object... args): Formats using this string as the format string, and the supplied arguments.
- String stripIndent(): Returns a string whose value is this string, with incidental white space removed from the beginning and end of every line.
- String translateEscapes(): Returns a string whose value is this string, with escape sequences translated as if in a string literal.
Those methods are associated with text blocks, a preview language feature. Text blocks and/or those methods may be changed or removed in a future release. Those why those APIs marked as Deprecated, for removal.
JEP355StringMethods.java
public class JEP355StringMethods {
public static void main(String[] args) {
String firstName = "Josefo";
String lastName = "Gaho";
String email = "[email protected]";
String sql = """
insert into CUSTOMER(FIRST_NAME, LAST_NAME, EMAIL)
values ('%s', '%s', '%s')
""".formatted(firstName, lastName, email);
System.out.println(sql);
String s = " Line 1\n" +
" Line 2\\n" +
" Line 3\n";
System.out.println("Without stripIndent():");
System.out.println(s);
System.out.println("With stripIndent():");
System.out.println(s.stripIndent());
System.out.println("With stripIndent() and translateEscapes():");
System.out.println(s.stripIndent().translateEscapes());
}
}
Will result:
insert into CUSTOMER(FIRST_NAME, LAST_NAME, EMAIL) values ('Josefo', 'Gaho', '[email protected]') Without stripIndent(): Line 1 Line 2\n Line 3 With stripIndent(): Line 1 Line 2\n Line 3 With stripIndent() and translateEscapes(): Line 1 Line 2 Line 3
Conclusion
Overall it’s a great preview. It’s good to see the much-awaited text blocks String support, especially since other languages that run on JVM, like Kotlin and Scala, have had support for multi-line text for quite some time now. It's a very useful feature, especially for us who working with "in-line" code like SQL or JSON. I'm looking forward for full-release version.
Reference: Programmer's Guide To Text Blocks
Desson AriawanProgrammer