Free Sun Certified Java Programmer Questions and Answers

Question 1

Which of the following accurately describes the main() method of an application?

Accepted Answer

public static void main( String args[] );

Answer

In Java, the `main` method serves as the entry point for any standalone application. Its signature must strictly be `public static void main(String[] args)`. `public` allows universal access, `static` enables calling without an object, `void` signifies no return value, and `String[] args` is an array for command-line arguments. Any deviation from this specific signature will prevent the Java Virtual Machine (JVM) from recognizing it as the application's starting point.

Question 2

Which of the following are keywords used in Java?

Accepted Answer

boolean

Answer

Java keywords are reserved words with predefined meanings that cannot be used as identifiers. `boolean` is a primitive data type keyword used to declare variables that can hold `true` or `false` values. `super` is a keyword used to refer to the immediate parent class object or to invoke a superclass's constructor or method. `Integer` is a class in the `java.lang` package, and `array` is a general concept, not a Java keyword.

Question 3

What identifiers are valid?

Accepted Answer

all of the above

Answer

In Java, identifiers (names for variables, methods, classes, etc.) must adhere to specific rules. They must start with a letter, an underscore (`_`), or a dollar sign (`$`). Subsequent characters can include letters, digits, underscores, or dollar signs. All the given options—`r2d2`, `bBb$`, and `_xpoints`—follow these rules, making them valid Java identifiers.

Question 4

The String variable s has "Hello Java" assigned to it in which of the following statements?

Accepted Answer

String s = new String("Hello Java");

Answer

Both `String s = new String("Hello Java");` and `String s = "Hello Java";` are valid ways to assign the literal "Hello Java" to a String variable `s`. The first explicitly creates a new String object using the constructor, while the second uses a String literal, which is a more common and often more efficient approach as Java can reuse String literals from the String pool. Options A and D contain incorrect syntax for String declaration and assignment.

Question 5

Which of the following is true:

Accepted Answer

>> performs signed shift while >>> performs an unsigned shift.

Answer

In Java, the `>>` operator performs a signed right shift, meaning it shifts bits to the right and fills the leftmost bits with the sign bit (0 for positive, 1 for negative), preserving the number's sign. Conversely, the `>>>` operator performs an unsigned right shift, which shifts bits to the right and always fills the leftmost bits with zeros, regardless of the original sign. This distinction is crucial for bitwise operations, especially with negative numbers.

SCJP - Sun Certified Java Programmer Practice Test

SCJP - Sun Certified Java Programmer Practice Test

Free Sun Certified Java Programmer Questions and Answers