FileInputStream fis = null;
try {
    fis = new FileInputStream("file.txt");
    // ...
} catch (FileNotFoundException e) {
    e.printStackTrace();
} finally {
    if (fis != null) {
        try {
            fis.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

try (FileInputStream fis = new FileInputStream("file.txt")) {
    // ...
} catch (IOException e) {
    e.printStackTrace();
}

List<String> names = Arrays.asList("Alice", "Bob", "Charlie");
for (String name : names) {
    System.out.println(name);
}

List<String> names = Arrays.asList("Alice", "Bob", "Charlie");
names.forEach(name -> System.out.println(name));

String s = "";
for (int i = 0; i < 10; i++) {
    s += i;
}

StringBuilder sb = new StringBuilder();
for (int i = 0; i < 10; i++) {
    sb.append(i);
}
String s = sb.toString();

System.out.println(Math.sqrt(2));

import static java.lang.Math.sqrt;
System.out.println(sqrt(2));

if (x < 0) {
    throw new IllegalArgumentException("x must be non-negative");
}

assert x >= 0 : "x must be non-negative";

String s = null;
if (s != null) {
    System.out.println(s.length());
}

Optional<String> optional = Optional.ofNullable(null);
optional.ifPresent(s -> System.out.println(s.length()));

public static final int STATUS_NEW = 0;
public static final int STATUS_PROCESSING = 1;
public static final int STATUS_COMPLETED = 2;

public enum Status {
    NEW,
    PROCESSING,
    COMPLETED
}

try {
    // ...
} catch (Exception e) {
    e.printStackTrace();
}

try {
    // ...
} catch (MyCustomException e) {
    e.printStackTrace();
}

List<Integer> numbers = Arrays.asList(1, 2, 3, 4, 5);
List<Integer> evenNumbers = new ArrayList<>();
for (int number : numbers) {
    if (number % 2 == 0) {
        evenNumbers.add(number);
    }
}

List<Integer> numbers = Arrays.asList(1, 2, 3, 4, 5);
List<Integer> evenNumbers = numbers.stream()

public class MyRunnable implements Runnable {
    private int count = 0;
    public void run() {
        for (int i = 0; i < 100000; i++) {
            count++;
        }
        System.out.println(count);
    }
}

public class MyRunnable implements Runnable {
    private ThreadLocal<Integer> count = new ThreadLocal<Integer>() {
        @Override
        protected Integer initialValue() {
            return 0;
        }
    };
    public void run() {
        for (int i = 0; i < 100000; i++) {
            count.set(count.get() + 1);
        }
        System.out.println(count.get());
    }
}