Free Sun Certified Java Programmer MCQ Questions and Answers

Question 1

Which of the following initialization strategies for the array "dayhigh" with seven values is correct?

Accepted Answer

int dayhigh[] = { 24, 23, 24, 25, 25, 23, 21 };

Answer

In Java, an array can be initialized directly at the time of declaration using an initializer list enclosed in curly braces. The syntax `int dayhigh[]` correctly declares an integer array named `dayhigh`. The `{ 24, 23, 24, 25, 25, 23, 21 }` part then initializes this array with the specified seven integer values, with the compiler inferring the array's size from the list.

Question 2

Which of the following claims regarding garbage collection in Java is accurate?

Accepted Answer

All of the above

Answer

All the statements regarding Java's garbage collection are accurate. The `finalize()` method is called before an object is garbage collected, though its execution time is not guaranteed. It is also best practice for `finalize()` methods to call their superclass's `finalize()` for proper resource cleanup. Lastly, the garbage collector can be explicitly suggested to run using `Runtime.getRuntime().gc()` or `System.gc()`, although the JVM retains control over its actual execution.

Question 3

Which procedures are necessary to implement the Runnable interface.

Accepted Answer

run()

Answer

The `Runnable` interface in Java is designed to encapsulate a task that can be executed by a thread. It is a functional interface, meaning it declares a single abstract method. This method is `run()`, which contains the actual code that a thread will execute when it starts.

Question 4

What causes a thread's execution to halt?

Accepted Answer

All of the above

Answer

A thread's execution can halt or pause due to several factors. Invoking `wait()` causes the thread to release its lock and enter a waiting state until notified. The `yield()` method suggests to the scheduler that the current thread is willing to give up its CPU time, allowing other threads to run. Additionally, a higher-priority thread becoming runnable can preempt a lower-priority thread, temporarily halting its execution.

Question 5

Which of the following methods can modify a String object, s?

Accepted Answer

none of the above will change s

Answer

String objects in Java are immutable, meaning their content cannot be changed after they are created. Methods like `concat()`, `equals()`, and `substring()` do not modify the original String object `s`. Instead, `concat()` and `substring()` return new String objects with the modified content, while `equals()` returns a boolean value indicating equality, leaving the original `s` unchanged.

SCJP - Sun Certified Java Programmer Practice Test

SCJP - Sun Certified Java Programmer Practice Test

Free Sun Certified Java Programmer MCQ Questions and Answers