Exam 8: User-Defined Classes

Which of the following class definitions is correct in Java? (i) Public class Employee { Private String name; Private double salary; Private int id; public Employee() { Name = ""; Salary = 0.0; Id = 0; } public Employee(String n, double s, int i) { Name = n; Salary = s; Id = i; } public void print() { System.out.println(name + " " + id + " " + salary); } } (ii) Public class Employee { Private String name; Private double salary; Private int id; public void Employee() { Name = ""; Salary = 0.0; Id = 0; } public void Employee(String n, double s, int i) { Name = n; Salary = s; Id = i; } Public void print() { System.out.println(name + " " + id + " " + salary); } }

The abstract data type specifies the logical properties and the implementation details.

MysteryClass -first: int -second: double; +MysteryClass() +MysteryClass(int) +MysteryClass(double); +MysteryClass(int, double) +setData(int, double): void +getFirst(): int +getSecond(): double +doubleFirst(): int +squareSecond(): double +print(): void +equals(MysteryClass): boolean +makeCopy(MysteryClass): void +getCopy():MysteryClass According to the UML class diagram in the accompanying figure, which of the following is a data member?

Members of a class are usually classified into three categories: public, private, and static.

Consider the following statements.public class Circle { Private double radius; public Circle() { Radius = 0.0; } public Circle(double r) { Radius = r; } public void set(double r) { Radius = r; } public void print() { System.out.println(radius + " " + area + " " + circumference); } public double area() { Return 3.14 * radius * radius; } public double circumference() { Return 2 * 3.14 * radius; }}Circle myCircle = new Circle(); Double r;Which of the following statements are valid in Java? (Assume that console is Scanner object initialized to the standard input device.) (i) R = console.nextDouble(); MyCircle.area = 3.14 * r * r; System.out.println(myCircle.area); (ii) R = console.nextDouble(); MyCircle.set(r); System.out.println(myCircle.area());

The non-static methods of a class are called instance methods.

In ____ copying, each reference variable refers to its own object.

Given the declaration public class MyClass { private int x; public void print() { System.out.println("x = " + x); } private void setX(int y) { x = y; } }MyClass myObject = new MyClass();The following statement is legal.myObject.setX(10);

Suppose that Book is class with two instance variables-name of type String and numOfBooks of type int. Which of the following would be appropriate syntax for the heading of a copy constructor for the class called Book?

If the object is created in the definition of a method of the class, then the object can access both the public and private members of the class.