Introduction To Java Programming Language

Answer: (iii) throw

throw explicitly throws an exception object. throws appears in a method declaration to announce exceptions that may propagate to the caller.

if (age < 18) throw new IllegalArgumentException("Underage");

Checked vs unchecked exceptions

Checked	Unchecked
Compiler requires catching or declaring them	No compile-time catch/declare requirement
Subclasses of Exception excluding RuntimeException	RuntimeException and its subclasses
Example: IOException, SQLException	Example: NullPointerException, ArithmeticException

import java.io.IOException;
class Example {
    static void read() throws IOException {
        throw new IOException("Read failed");
    }
    public static void main(String[] args) {
        try { read(); }
        catch (IOException e) { System.err.println(e.getMessage()); }
    }
}

Catch exceptions when recovery is possible, or declare checked exceptions with throws. Prevent unchecked exceptions through validation and correct program logic; do not catch Exception indiscriminately.

Thread priorities

Java priorities range from Thread.MIN_PRIORITY (1) to Thread.NORM_PRIORITY (5) and Thread.MAX_PRIORITY (10). Set one using thread.setPriority(7) and inspect it with getPriority().

Priorities are hints to the scheduler, not a promise of execution order. Scheduling policies vary by JVM and operating system; threads may run in an order different from their priority. Correctness must rely on synchronization primitives (synchronized, locks, queues, latches), not priority. Avoid using priority as a substitute for coordination.