try {
  int number = Integer.parseInt("a");
} catch (NumberFormatException e) {
  System.err.println("Not a number");
}

try {
  int number = Integer.parseInt("a");
} catch (NumberFormatException _) {
  System.err.println("Not a number");
}

Map<String, Integer> map = new HashMap<>();
map.put("John", 5);
map.forEach((_, x) -> System.out.println(x))

public class Rectangle {
  String color;
  double width;
  double length;

  public Rectangle(String color, double width, double lenght) {
      color = color;
      width = width;
      length = length;
    }
};

public class Square extends Rectangle {
  public Square(String color, int area) {
    this(color, Math.sqrt(validateArea(area)));
  }

  private static int validateArea(int area) {
    if (area < 0) throw new IllegalArgumentException();
    return area;
  }

  private Square(String color, double sideLength) {
    super(color, sideLength, sideLength);
  }
}

public class Square extends Rectangle {
  public Square(String color, int area) {
    if (area < 0) throw new IllegalArgumentException();
    double sideLength = Math.sqrt(area);
    super(color, sideLength, sideLength);
  }
}

Stream.of(1,2,3,4,5,6,7,8).gather(Gatherers.windowFixed(3)).toList();

Stream.of(1,2,3,4,5,6,7,8).gather(Gatherers.windowSliding(2)).toList();

Stream.of(1,2,3,4,5,6,7,8).gather(Gatherers.windowSliding(6)).toList();

Stream.of(1,2,3,4,5,6,7,8,9).gather(
  Gatherers.fold(() -> "", (string, number) -> string + number)
).findFirst();

 Stream.of(1,2,3,4,5,6,7,8,9).
  gather(
    Gatherers.scan(() -> "", (string, number) -> string + number)
  ).toList();

 Stream.of("a","b","c","d","e","f","g","h","i").
  gather(
    Gatherers.mapConcurrent(10, s -> s.toUpperCase(Locale.ROOT))
  ).toList();

import java.lang.foreign.Linker;
import java.lang.foreign.SymbolLookup;
import java.lang.foreign.FunctionDescriptor;
import java.lang.foreign.ValueLayout;
import java.lang.foreign.MemorySegment;
import java.lang.foreign.Arena;
import java.lang.invoke.MethodHandle;

SymbolLookup stdlib = Linker.nativeLinker().defaultLookup();

MethodHandle strlen = Linker.nativeLinker().downcallHandle(
  stdlib.find("strlen").orElseThrow(),FunctionDescriptor.of(
    ValueLayout.JAVA_LONG, ValueLayout.ADDRESS));

try (Arena offHeap = Arena.ofConfined()) {
  MemorySegment str = offHeap.allocateFrom("Happy Coding!");
  long len = (long) strlen.invoke(str);
  System.out.println("len = " + len);
}