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Language Beginner

Pattern matching for instanceof

Combine type check and cast in one step with pattern matching.

Code Comparison

✕ Java 8

if (obj instanceof String) {
    String s = (String) obj;
    int length = s.length();
    // do something with 'length'
}

✓ Java 16+

if (obj instanceof String s) {
   int length = s.length();
    // do something with 'length'
}

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Why the modern way wins

🔄

No redundant cast

Type check and variable binding happen in a single expression.

📏

Fewer lines

One line instead of two — the cast line disappears entirely.

🛡️

Scope safety

The pattern variable is only in scope where the type is guaranteed.

Old Approach

instanceof + Cast

Modern Approach

Pattern Variable

Since JDK

Difficulty

Beginner

JDK Support

Pattern matching for instanceof

Available

Widely available since JDK 16 (March 2021)

How it works

Pattern matching for instanceof eliminates the redundant cast after a type check. The variable is automatically scoped to where the pattern matches, making code safer and shorter.

Compact source files

Java 8

public class HelloWorld {
    public static void main(String[] args) {
        System.out.println(
            "Hello, World!");
    }
}

Java 25

void main() {
    IO.println("Hello, World!");
}

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JDK 25+ →

Language Beginner

Type inference with var

Java 8

Map<String, List<Integer>> map =
    new HashMap<String, List<Integer>>();
for (Map.Entry<String, List<Integer>> e
    : map.entrySet()) {
    // verbose type noise
}

Java 10+

var map = new HashMap<String, List<Integer>>();
for (var entry : map.entrySet()) {
    // clean and readable
}

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JDK 10+ →

Language Beginner

Text blocks for multiline strings

Java 8

String json = "{\n" +
    "  \"name\": \"Duke\",\n" +
    "  \"age\": 30\n" +
    "}";

Java 15+

String json = """
    {
      "name": "Duke",
      "age": 30
    }""";

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JDK 15+ →