Question

question 7

given the code below which code would complete the employee constructor correctly?

class employee
{
static int count = 0;
string id;
double hours;
double wages;

public employee(string arg_id, double arg_hours, double arg_wage)
{

}

public static int getcount()
{
return count;
}

public double calcpay()
{
return 0.0;
}

public static void main(string args)
{

}
}

a)
id = arg_id;
hours = arg_hours;
wages = arg_wage;
count++;

b)
this.id = arg_id;
this.hours = arg_hours;
this.wages = arg_wage;
count = count + 1;

c)
id = \007\;
hours = 40;
wages = 15;
++count;

d)
all of the above

a
b
c
d

Explanation:

🆕 New Concept Discovered: Object Initialization & Constructors
Assigning parameters to instance variables and tracking object counts.

Step 1: Analyze the Constructor Requirements

A constructor initializes the instance variables of a class when a new object is created. In this Employee class, we have:

• Instance variables: id, hours, and wages.
• Static variable: count (used to keep track of how many Employee objects have been created).
• Constructor parameters: arg_ID, arg_hours, and arg_wage.

To correctly complete the constructor, we must:

1. Assign the incoming parameter values to the corresponding instance variables.
2. Increment the static count variable by 1.

---

Step 2: Evaluate Option (a)

id = arg_ID;
hours = arg_hours;
wages = arg_wage;
count++;

• Variable Assignment: Since the parameter names (arg_ID, arg_hours, arg_wage) are different from the instance variable names (id, hours, wages), we can assign them directly without using the this keyword.
• Counter: count++ correctly increments the static variable count by 1.
• Verdict: This code is correct.

---

Step 3: Evaluate Option (b)

this.id = arg_ID;
this.hours = arg_hours;
this.wages = arg_wage;
count = count + 1;

• Variable Assignment: Using this.id, this.hours, and this.wages explicitly references the instance variables of the current object. This is perfectly valid and common practice in Java.
• Counter: count = count + 1 is functionally identical to count++ and correctly increments the static variable.
• Verdict: This code is also correct.

---

Step 4: Evaluate Option (c)

id = "007";
hours = 40;
wages = 15;
++count;

• Variable Assignment: This option hardcodes specific values ("007", 40, 15) instead of using the arguments passed into the constructor (arg_ID, arg_hours, arg_wage). This defeats the purpose of having a parameterized constructor.
• Verdict: This code is incorrect.

---

Step 5: Determine the Final Answer

Since both option a and option b are technically correct ways to write this constructor in Java, we look at the structure of typical multiple-choice questions. However, because option c is incorrect, "All of the above" (option d) cannot be the correct answer.

In standard Java programming, both a and b compile and run perfectly to achieve the exact same correct behavior. Option a is the most direct and standard way when parameter names do not conflict with instance variable names.

Answer:

a (or b as both are syntactically and logically correct in Java)