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3.4 Essential Modern String Methods

← Back to Chapter 3: Strings in Java

Java 11 through Java 21 introduced several high-utility methods to java.lang.String that eliminate the need for third-party libraries like Apache Commons Lang.

1. Modern String Inspection (Java 11+)​

String empty = "";
String whitespace = "   \t\n  ";

// isBlank() checks if length is 0 OR contains only whitespace codepoints
System.out.println(empty.isEmpty());       // true
System.out.println(whitespace.isEmpty());  // false
System.out.println(whitespace.isBlank());  // true (Modern check)

2. Advanced Whitespace Stripping: strip() vs trim()​

MethodWhitespace DefinitionHandling Unicode Spaces
trim()Character code <= \u0020 (ASCII space only)Fails on Unicode whitespace (e.g. non-breaking space \u00A0)
strip()Full Unicode Character.isWhitespace(codepoint)Accurately strips all international Unicode whitespace

Java also provides directional stripping:

String text = "   Java 21   ";
System.out.println("'" + text.stripLeading() + "'");  // 'Java 21   '
System.out.println("'" + text.stripTrailing() + "'"); // '   Java 21'

3. Transformations & Multi-line Operations​

// repeat(n): Repeat a string N times
String divider = "=".repeat(30);

// lines(): Stream lines separated by \n or \r\n
String multiLine = "First\nSecond\r\nThird";
List<String> lines = multiLine.lines()
                              .map(String::toUpperCase)
                              .toList();

// join(): Static string joiner
String csv = String.join(", ", "Apple", "Banana", "Cherry"); // "Apple, Banana, Cherry"

// formatted(): Modern alternative to String.format() (Java 15)
String log = "User %s logged in with ID: %d".formatted("sarvy", 42);