Java के Advanced Interview सवाल

public class Main {
	static void readFile() throws java.io.IOException { // checked -- must be declared or caught
		throw new java.io.IOException("file missing");
	}
	static void process() { // no throws clause needed for unchecked
		throw new RuntimeException("unchecked -- skips compile-time enforcement");
	}
	public static void main(String[] args) {
		try { readFile(); } catch (java.io.IOException e) { System.out.println("Checked: " + e.getMessage()); }
		try { process(); } catch (RuntimeException e) { System.out.println("Unchecked: " + e.getMessage()); }
	}
}

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import java.util.*;
public class Main {
	public static void main(String[] args) {
		Map<Integer, String> map = new HashMap<>();
		map.put(1, "a"); map.put(17, "b"); // both may land in the same bucket depending on capacity
		System.out.println(map.get(1) + " " + map.get(17)); // chained within the bucket, still found correctly
	}
}

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public class Main {
	static int counter = 0;
	static final Object lock = new Object();
	static synchronized void incrementWholeMethod() { counter++; } // locks the whole object
	static void incrementBlockOnly() {
		synchronized (lock) { counter++; } // locks only these lines
	}
	public static void main(String[] args) {
		incrementWholeMethod();
		incrementBlockOnly();
		System.out.println(counter);
	}
}

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import java.util.*;
public class Main {
	static class Person implements Comparable<Person> {
		String name; int age;
		Person(String name, int age) { this.name = name; this.age = age; }
		public int compareTo(Person o) { return Integer.compare(age, o.age); } // natural order, baked in
	}
	public static void main(String[] args) {
		List<Person> people = new ArrayList<>(List.of(new Person("Bo", 30), new Person("Al", 20)));
		Collections.sort(people); // uses Comparable
		people.sort(Comparator.comparing(p -> p.name)); // Comparator, external alternative order
		System.out.println(people.get(0).name);
	}
}

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public class Main {
	static class Address { String city; Address(String city) { this.city = city; } }
	static class Person {
		Address address;
		Person(Address address) { this.address = address; }
		Person shallowCopy() { return new Person(this.address); } // shares the same Address
		Person deepCopy() { return new Person(new Address(this.address.city)); } // new nested object
	}
	public static void main(String[] args) {
		Person original = new Person(new Address("Delhi"));
		Person shallow = original.shallowCopy();
		Person deep = original.deepCopy();
		System.out.println(original.address == shallow.address);
		System.out.println(original.address == deep.address);
	}
}

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