A Programmer[ap]s Guide to Java Certification

Which one of these is a valid method declaration?

Select the one correct answer.

1. void method1 { /* ... */ }

2. void method2() { /* ... */ }

3. void method3(void) { /* ... */ }

4. method4() { /* ... */ }

5. method5(void) { /* ... */ }

Given the following code, which statements can be placed at the indicated position without causing compilation errors?

public class ThisUsage { int planets; static int suns; public void gaze() { int i; // ... insert statements here ... } }

Select the three correct answers.

1. i = this.planets;

2. i = this.suns;

3. this = new ThisUsage();

4. this.i = 4;

5. this.suns = planets;

Given the following pairs of method declarations, which statements are true?

void fly(int distance) {} int fly(int time, int speed) { return time*speed; } void fall(int time) {} int fall(int distance) { return distance; } void glide(int time) {} void Glide(int time) {}

Select the two correct answers.

1. The first pair of methods will compile correctly and overload the method name fly .

2. The second pair of methods will compile correctly and overload the method name fall .

3. The third pair of methods will compile correctly and overload the method name glide .

4. The second pair of methods will not compile correctly.

5. The third pair of methods will not compile correctly.

Given a class named Book , which one of these is a valid constructor declaration for the class?

Select the one correct answer.

1. Book(Book b) {}

2. Book Book() {}

3. private final Book() {}

4. void Book() {}

5. public static void Book(String[] args) {}

6. abstract Book() {}

Which statements are true?

Select the two correct answers.

1. All classes must define a constructor.

2. A constructor can be declared private .

3. A constructor can return a value.

4. A constructor must initialize all the fields of a class.

5. A constructor can access the non-static members of a class.

What will be the result of attempting to compile the following program?

public class MyClass { long var; public void MyClass(long param) { var = param; } // (1) public static void main(String[] args) { MyClass a, b; a = new MyClass(); // (2) b = new MyClass(5); // (3) } }

Select the one correct answer.

1. A compilation error will occur at (1), since constructors cannot specify a return value.

2. A compilation error will occur at (2), since the class does not have a default constructor.

3. A compilation error will occur at (3), since the class does not have a constructor which takes one argument of type int .

4. The program will compile correctly.