Tag: database

In order to stay in practice with good Java programming techniques, I have decided to write a database. It stores only employees, allows logged in users to retrieve / hire employees, and has a sign-in mechanism that prevents the use of methods when you are not logged in. I'm looking for feedback in the following areas:

• structure Is the overall structure of the program good? Are there any improvements that can make the structure of the program more efficient / compact?
• Login mechanism Is the way I implemented this system alright? Is there a better way to implement this login system?
• exceptions I have created two custom exceptions for this program. Is the way I coded these exceptions acceptable? Should I have had one? Custom exception Class from which they could inherit so that I can only have the message print error message as parameter / hard coded? I use darkness when writing these exceptions, so that the serialVersionUID is generated automatically.
• Efficiency / compactness Is there a way to make this program more efficient? Just like that getHighestSalary Method in the Database class.

All suggestions are asked and appreciated. Style and other cleanliness tips are also recommended.

Database.java

Package database;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

public class Database {

private ArrayList employees;
private final string username;
private final string password;
private boolean logged in;

public database () {

this.employees = new ArrayList();
this.username = generateUsername ();
this.password = generatePassword ();
this.loggedIn = false;

populateEmployees ();
}

public void addEmployee (Employee employee) triggers LoginException {
if (logged in) {
this.employees.add (staff);
sortEmployees ();
Return;
}
trigger new LoginException ("Not logged in!");
}

public Employee getHighestSalary () triggers LoginException {
if (logged in) {
Employee highest = this.employees.get (0);
for (Employee Employee: this.employees) {
if (employee.getSalary ()> highest.getSalary ()) {
highest = employee;
}
}
return the highest;
}
trigger new LoginException ("Not logged in!");
}

@SuppressWarnings ("deactivated")
public void sortEmployees () triggers LoginException {
if (logged in) {
Collections.sort ((List) this.employees);
Return;
}
trigger new LoginException ("Not logged in!");
}

public Employee getEmployee (String name) triggers EmployeeNotFoundException, LoginException {
if (logged in) {
for (Employee Employee: this.employees) {
if (employee.getName (). equals (name)) {
Return employee;
}
}
Trigger new EmployeeNotFoundException ("Employee Not Found!");
}
trigger new LoginException ("Not logged in!");
}

// filler for tester class
private void populateEmployees () {
for (int i = 0; i <10; i ++) {
this.employees.add (new employee ("Employee" + i));
}
}

public void login (string username, string password) {
if (this.username.equals (username) && this.password.equals (password)) {
this.loggedIn = true;
}
}

public ArrayList getEmployees () triggers LoginException {
if (logged in) {
Give this back.
}
trigger new LoginException ("Not logged in!");
}

// used for testing
private string generateUsername () {
return "username123";
}

// used for testing
private string generatePassword () {
return "password123";
}

}

Employee.java

Package database;

public class employee {

private final string name;
private int age;
private int salary;


public employee (String name) {
this.name = name;
}

public employee (string name, int age) {
this.name = name;
this.age = age;
}

Public employee (string name, int. Age, int. Salary) {
this.name = name;
this.age = age;
this.salary = salary;
}

public String getName () {return this.name; }
public int getAge () {return this.age; }
public int getSalary () {return this.salary; }

public String toString () {
return "name:" + this.name;
}

}

LoginException.java

Package database;

public class LoginException extends Exception {

private static final long serialVersionUID = 1L;

public LoginException (String message) {
great (message);
}

public void printErrorMessage () {
System.out.println ("LoginException: Not logged in!");
}

}

EmployeeNotFoundException.java

Package database;

public class EmployeeNotFoundException extends Exception {

private static final long serialVersionUID = 1L;

public EmployeeNotFoundException (String message) {
great (message);
}

public void printErrorMessage () {
System.out.println ("EmployeNotFoundException: The employee was not found!");
}

}

Tester.java

Package database;

public class testers {

@SuppressWarnings ("unused")
public static void main (String[] Arguments) {
Database database = new Database ();
database.login ("username1234", "password123");

// Should `LoginException` trigger
To attempt {
for (employee employees: database.getEmployees ()) {
System.out.println (employee);
}
} catch (LoginException e) {
e.printErrorMessage ();
}

// Should `EmployeeNotFoundException` trigger
To attempt {
Employee test = database.getEmployee ("Ben");
} catch (EmployeeNotFoundException e) {
e.printErrorMessage ();
} catch (LoginException e) {
e.printErrorMessage ();
}

}

}