METCS526-Homework 1 Java Basics Solved

This assignment is practice of Java basics.  

 

Problem 1 An incomplete Java program named Hw1_P1_incomplete.java is posted on the course website. You must complete the program by implementing the following requirements. Don’t forget to delete “_incomplete” from the file name.

 

This program has three methods. The first method receives an array of integers and calculates the average, the minimum, and the maximum of the integers and prints them on the screen.  

 

The signature of this method is:

 

public static void stats(int[ ] numbers)

 

The second method creates and prints a subarray of a given array. The specification of the method is:

 

•        Signature of method:  

 

public static void subarray(int[ ] a, int from, int to)

 

•        Input arguments:

a: An array of integers from: The index of an element in a which becomes the first element in the subarray to: The index of an element in a which becomes the last element in the subarray  Behavior:  

•        A new integer array is created, which is a subarray of a, and it includes elements a[from] to a[to], inclusively.

•        Prints the subarray.

•        There is no return value.

 

The third method is a main method. If you run this program with the following main method:

 

public static void main(String[] args) { 

                             int[] a = {15, 25, 10, 65, 30, 55, 65};            System.out.print("\nGiven array is: "); 

              for (int i=0; i<a.length‐1; i++) { 

                     System.out.print(a[i] + ", "); 

              } 

              System.out.print(a[a.length ‐ 1]); 

              System.out.println(); 

               

              stats(a); 

              subarray(a, 1, 4); 

 

Your output should be:

 

Given array is: 15, 25, 10, 65, 30, 55, 65 

 average = 37.86, min = 10, max = 65 

 

The subarray, from index 1 to index 4, is: 25, 10, 65, 30 

 

 

Problem 2 For this problem, first you need to write a subclass of the Employee class. The definition of the Employee class is in the Employee.java file and it is briefly described below:

 

Class Employee

 

Instance variables  empId:   

•        Description: Employee id of an employee

•        Type: integer  name:

•        Description: Name of an employee

•        Type: String

 

Instance methods:

•        getEmpId

•        No input argument

•        Returns the employee id

•        getName

•        No input argument

•        Returns the employee name

•        setEmpId

•        Input argument: empId of integer type

•        Existing empId is replaced with the given empId

•        No return value

•        setName

•        Input argument: name of String type

•        Existing name (which may be null) is replaced with the given name  No return value

 

You need to implement the following class, which is a subclass of the Employee class. Define this class in a separate file named SalariedEmployee.java.

 

Class SalariedEmployee 
 

•        A subclass of the Employee class

•        Instance variables

•        salary: annual salary; double type

•        Instance method

•        monthlyPayment

•        No input argument

•        Returns monthly payment; double type

•        Monthly payment is calculated as salary / 12

•        employeeInfo  

•        No input argument

•        Displays the empId, name, salary, and monthly payment

•        No return value

 

In the subclass definition, you must implement all necessary get methods and set methods.

 

Then, write a program, named Hw1_P2.java, that reads employee information from a text file and stores SalariedEmployee objects in an array of size 10, named employeeArray, and displays employees satisfying a certain criterion. Follow the instruction below:

 

•        Write a method, named employeesAbove, whose behavior is specified below:

 

•        Signature of method:  

 

public static void employeesAbove (SalariedEmployee[ ] empArray, double threshold)

 

•        Input arguments: empArray: An array of SalariedEmployee objects threshold: A salary threshold

•        Behavior: Selects from empArray only those employees who earn more than the given threshold amount, and displays their empId, name, salary, and monthly payment.

•        There is no return value.

 

•        In the main method, do the following:

 

•        Read information of 10 salaried employees from an input file named employee_input.txt and create 10 SalariedEmployee objects and store them in employeeArray. A sample input file is shown below:

 

1, John, 50000

2, Susan, 120000

3, Yapsiong, 80000

4, Gomez, 90000

5, Minsky, 60000

6, Yorst, 30000

7, Govindranad, 40000

8, Kelsey, 60000

9, Jake, 110000

10, Guanyu, 70000

 

•        Invoke the employeesAbove method a few times with different threshold values and check that your output is correct. If, for example, you invoke the method with the threshold 70000, then the output should be:

 

Employees earning more than $70000:   

 

                      Employee id = 2 

                      Name = Susan 

                      Salary = 120000.00 

                      Monthly pay = 10000.00 

 

                      Employee id = 3 

                      Name = Yapsiong 

                      Salary = 80000.00 

                      Monthly pay =  6666.67 

 

                      Employee id = 4 

                      Name = Gomez 

                      Salary = 90000.00 

                      Monthly pay =  7500.00 

 

                      Employee id = 9 

                      Name = Jake 

                      Salary = 110000.00 

                      Monthly pay =  9166.67