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Strings Beginner

String chars as stream

Process string characters as a stream pipeline.

Code Comparison

✕ Java 8

for (int i = 0; i < str.length(); i++) {
    char c = str.charAt(i);
    if (Character.isDigit(c)) {
        process(c);
    }
}

✓ Java 9+

str.chars()
    .filter(Character::isDigit)
    .forEach(c -> process((char) c));

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Why the modern way wins

🔗

Chainable

Use filter, map, collect on character streams.

📐

Declarative

Describe what to do, not how to loop.

🌐

Unicode-ready

codePoints() correctly handles emoji and supplementary chars.

Old Approach

Manual Loop

Modern Approach

chars() Stream

Since JDK

Difficulty

Beginner

JDK Support

String chars as stream

Available

Available since JDK 8+ (improved in 9+)

How it works

String.chars() returns an IntStream of character values, enabling functional processing. For Unicode support, codePoints() handles supplementary characters correctly.

String.repeat()

Java 8

StringBuilder sb = new StringBuilder();
for (int i = 0; i < 3; i++) {
    sb.append("abc");
}
String result = sb.toString();

Java 11+

String result = "abc".repeat(3);
// "abcabcabc"

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JDK 11+ →

Strings Beginner

String.isBlank()

Java 8

boolean blank =
    str.trim().isEmpty();
// or: str.trim().length() == 0

Java 11+

boolean blank = str.isBlank();
// handles Unicode whitespace too

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JDK 11+ →

Strings Beginner

String.formatted()

Java 8

String msg = String.format(
    "Hello %s, you are %d",
    name, age
);

Java 15+

String msg =
    "Hello %s, you are %d"
    .formatted(name, age);

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JDK 15+ →