strings - Expand concept by newline and text blocks

fapdash · fapdash · commit 16b9df051f78 · 2025-04-27T17:42:42.000+02:00
- Add multi-line strings / text blocks (Java 15)
- Add explanation of newlines / end of line chars,
  so students can understand the motivation behind text blocks
diff --git a/concepts/strings/.meta/config.json b/concepts/strings/.meta/config.json
@@ -3,5 +3,7 @@
   "authors": [
     "mirkoperillo"
   ],
-  "contributors": []
+  "contributors": [
+    "fapdash"
+  ]
 }
diff --git a/concepts/strings/about.md b/concepts/strings/about.md
@@ -22,6 +22,29 @@ String escaped = "c:\\test.txt";
 // => c:\test.txt
 ```
 
+To put a newline character in a string, use the `\n` escape code (`\r\n` on Windows):
+
+```java
+"<html>\n    <body>\n        <h1>Hello, World!</h1>\n    </body>\n</html>\n"
+```
+
+For code that should work on different operating systems Java offers [`System.lineSeparator()`][system-line-separator], which returns the system-dependent line separator string.
+
+To comfortable work with texts that contain a lot of newlines you can use [Text Blocks](text-blocks).
+These multi-line strings are delimited by triple double quote (`"`) characters.
+
+
+```java
+String multilineHtml = """
+<html>
+    <body>
+        <h1>Hello, World!</h1>
+    </body>
+</html>
+""";
+// => "<html>\n    <body>\n        <h1>Hello, World!</h1>\n    </body>\n</html>\n"
+```
+
 Finally, there are many ways to concatenate a string.
 The simplest one is the `+` operator:
 
@@ -35,15 +58,26 @@ For any string formatting more complex than simple concatenation, `String.format
 
 ```java
 String name = "Jane";
-String.format("Hello %s!",name);
+String.format("Hello %s!", name);
 // => "Hello Jane!"
 ```
 
-Other possibilities are:
+The conversion `%n` in a format string inserts a system-dependent line separator.
+
+```java
+String name = "Jane";
+String.format("Hello,%n%s!", name);
+// => "Hello,\nJane!" (Linux, macOS)
+// => "Hello,\r\nJane!" (Windows)
+```
+
+Other possibilities to build more complex strings are:
 
 - use [`StringBuilder` class][string-builder]
 - use [`String.concat` method][string-concat]
 
 [string-class]: https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/lang/String.html
+[text-blocks]: https://openjdk.org/projects/amber/guides/text-blocks-guide
 [string-builder]: https://docs.oracle.com/javase/tutorial/java/data/buffers.html
 [string-concat]: https://docs.oracle.com/javase/8/docs/api/java/lang/String.html#concat-java.lang.String-
+[system-line-separator]: https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/lang/System.html#lineSeparator()

Original file line number	Diff line number	Diff line change
`@@ -3,5 +3,7 @@`
`3`	`3`	`"authors": [`
`4`	`4`	`"mirkoperillo"`
`5`	`5`	`],`
`6`		`- "contributors": []`
	`6`	`+ "contributors": [`
	`7`	`+ "fapdash"`
	`8`	`+ ]`
`7`	`9`	`}`