How to Create & Display Array of Objects in Java example
Your current Emp class could have problems even when used in a HashSetsince two employees with the same name can work in the same company for the same salary, and the HashSet won't be able to distinguish between them. You should add some unique identifier to the Emp class.
That unique member can serve as the key in a Map. It can also be used in the calculation of hashCode and equals instead of the other propertiessince it uniquely identifies the employee. Actually keys in HashMap is a similar thing to values in HashSetthere is no big difference between them. The only question what is unique constraints for your object, I would ask interviewer about that and suggest to use either name or add some additional unique identifier e.
Once these methods correctly defined - you can use Employee class itself as a HashMap key with no doubts. Going further to the source code of the HashSet - we see that it actually use a HashMap inside and add our values as a HashMap's keys with a dummy internal object as each Map's entry value, check the constructor and add method:. You should make it immutable with final keyword. Learn more. Asked 5 years, 3 months ago. Active 1 year, 8 months ago. Viewed 8k times. I think a combination string of all three fields could be the key like 'Ram-Trainer'.
I'll put it like this: your compareTo is incomplete; it doesn't take into account nullnor does it make use of generics anywhere. Right now, you've got a chance for a ClassCastException due to the fact that your compareTo doesn't take an Emp object. Active Oldest Votes. Eran Eran k 43 43 gold badges silver badges bronze badges. I agree with Eran. You should create some unique id. This is also a common method in databases.Hello there jimmy, I was examining your above code about Employee record management.
Since I am working on java, I executed your code and got some error in your above code. I want you to resolve the problem which I am going to mention below.
Why did you use compareTo method in Employee Class. While adding employee detail for second time it is giving me an error, where you thrown an exception. Skip to content. Instantly share code, notes, and snippets.Sort a list of objects by two fields in Java
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Download ZIP. A simple Java program to keep track of employees in a company which implements HashMap and TreeSet data sructures. Scanner ; import java. This comment has been minimized. Sign in to view. Copy link Quote reply. Same error was encountered by me.
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Already have an account? Sign in to comment. You signed in with another tab or window. Reload to refresh your session. You signed out in another tab or window.Ben Blackburn wrote:. I was wondering if this would also make it easier to verify a valid gender has been entered? Forum: Java in General. Help writing a program to add an manage employees. Ben Blackburn. Hi everyone, I'm new here and new to java programming and I have a rather large task to complete. I've only just started and got to around number 3 before I started thinking maybe I'm not writing the best code.
I'll post the code and if anyone has any tips or spots any errors to please let me know so I can write better code. Also if anyone has any hints for the rest of the questions I would be grateful for any help you can provide as some of the stuff I have not come across before.
Thank you I have to use an array to write a program to store and manage a set of employees working in a small supermarket according to the following requirements: 1 There is a need to record details about each employee in the supermarket. Note: Create an array of type Employee where Employee is a class you create containing the name, address, DOB and gender as instance variables. You must check that the Gender has been entered correctly in whatever format you specify.
You must also inform the user that if any of the fields are left blank for an employee, the employee's full details will not be saved beyond that current session.
Note: Deleting data from an array may leave a blank space in the array, so keep a count of the number of employees and search for the next free array cell when adding another employee. This report should include the name of the supermarket, the name of the supermarket owner, the total number of employees excluding the owner that are currently working there and the percentages of the workforce that are male and female.
The two sets of details must be saved to two standard text files. The supermarket's details are to be saved to a file named" SupermarketDetails. Note: Do NOT save blank records to disk, check that there is a valid "Employee" object in each array cell before writing its contents to disk.
If any of the fields within an employee's details have been left blank string length of zero then that employee is invalid and their details should not be written to disk. Note: Each record requires a new instance of the Employee class to be created and linked to the next available free cell in your array. Stefan Evans. Looks ok so far.
Java Program to Calculate Salary of an Employee
Here are some things to think about: You are storing your employees in a variable called 'supermarket'. Consider renaming it. Date of birth might be better represented as a Date object rather than a string object. Similarly Gender might be better off as a different data type.
I know I would use an Enumeration, but you may not have learned about those yet. Does a supermarket have details other than its employees? You could perhaps make the Supermarket name and owner instance variables of the Supermarket class. Rather than having a "printDetails" method, you might consider implementing getter methods or a "toString " method for each object.
For instance the employee class has private variables great. You set these up originally in the constructor, but the only way to get at them right now is to print them out via your printDetails method. For instance having some junit tests that make sure everything is working Campbell Ritchie.
And welcome to the Ranch. Thanks for the help so far guys.
I have since changed the name from supermarket to list, since it is basically a list of employees. I was reading about enums just now and you're right we have not come across those yet.Programming Unit. Here we have a parent class Employee in which we have declared variables like name, address, gender and age. We take the input of these variables by invoking the Constructor.
We also have a method called display which is used to display the details of the Employee. Second class fullTimeEmployees inherits the Employee class and is used to get the designation and salary of an Employee. We have a method display which first calls the super method i. Third class partTimeEmployees inherits the Employee class and is used to get the Working hours of a part time employee.
We have the same display method which first class the super display method and prints the other details. In the Employees class we are creating objects to the fullTimeEmployees and partTimeEmployees classes.
We can implement this program using array of objects also. Receive an email as soon as we publish an article on ProgrammingUnit.
Can anyone suggest any changes to make it more OO? Each variable has a scope where it is visible. So when we need temp variables, we can declare them in the inner scope where they are needed. The fewer variables in an outer scope we have, the easier a program is to understand. You should avoid variables that are public, static, or in outer scopes, because these are in a sense global variables. There are often better ways to access your data, e. A variable name should make it obvious what this variable does.
For example, you have two variables sc and sd. These are bot scanners around the System.
Retrieving employee details by giving employee id - Java
You never explain what their difference is. Good variable names don't tell use what their content is we can already see the type at the variable declarationbut rather what its purpose is. What is list? Yes, I can see that it's a Listthankyou very much. Oh, it's a collection of all employess? A few lines later, you have tempstring1 through tempstring7. It is impossible to know from these names what they are supposed to do. It seems tempstring1 should be name and tempstring4 should be addressbut it is difficult to understand the relevant code because it is obscured with these unintelligible variable names.
Use better names! They cost you nothing, and make code much easier to read. And above all, avoid single-letter names. A magic number is a number that occurs in the source code without explanation why this specific number is needed here. Numbers like 0 or 1 are often obvious, but anything else should be explained.
The problem is that these numbers often contain assumptions about your data that can be invalidated without you realizing it. When the data changes, and your program isn't updated accordingly, then you get bugs that are difficult to track down. The number 5 is a magic number here. Where does it come from? Ah, of course it's from your arrays like names. Using names. If you make certain assumptions you can also test them for validity with asserts.
An assert is an expression that expresses a state which you as a programmer know to be true, but you want to make sure. Here, an assertion that all of your input arrays have the same length seems like a good idea:. Wow, is that a lot code for so little. Instead of spreading your data of one employee across several arrays and then later building it, you might as well construct them directly:. When iterating over each element of a Java collection, using.Sometimes we need to store the objects to the file system, and need to read them whenever required.
Below example shows how to store the objects to the file, and how to retrieve them from the file. I'm Nataraja Gootooru, programmer by profession and passionate about technologies. All examples given here are as simple as possible to help beginners. The source code is compiled and tested in my dev environment. An adapter class provides the default implementation of all methods in an event listener interface. Adapter classes are very useful when you want to process only few of the events that are handled by a particular event listener interface.
You can define a new class by extending one of the adapter classes and implement only those events relevant to you. About Author I'm Nataraja Gootooru, programmer by profession and passionate about technologies. Java Data Structures Java 8 new features Write a program to find common integers between two sorted arrays. Publish Your Article Here. Program: How to store and read objects from a file? FileInputStream; import java. FileNotFoundException; import java. FileOutputStream; import java.
IOException; import java. InputStream; import java. ObjectInputStream; import java. ObjectOutputStream; import java. OutputStream; import java. Show list of all file names from a folder. How to get list of all files from a folder? Filter the files by file extensions and show the file names.
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Java Program of Employee Details
How to store and read objects from a file? How to create and store property file dynamically? How to store property file as xml file? How to get file last modified time?It contains employee information like employee id, first name, surname, and age.
It is an easy to use application and has a user-friendly interface. It is totally built at the administrative end which means that only the admin has access rights to change or modify any records. So this makes it safe and reliable application to use. The main aim of developing this application was to reduce the errors that occur in the manual system. One can search the details easily by just entering employee id.
In earlier systems, there was not such a facility to do so. All the details are stored in an SQLite database. It is easy to update any employee details. All the employee records are integrated and so this makes it user-friendly and easy to use application. Employee Management System Project in Java is Java project developed using java GUI or java swings and this comes under java projects with source code.
Earlier systems were manual where there was no way of properly storing information. Employee records were stored manually which lead to errors. There was no proper way of tracking employee records. It was very difficult and required a lot of paperwork which makes the application time consuming and not secured. There was no administrator which could handle the records.
So there was the need to develop a system which could manage all these things and reduce the paperwork. Employee information system is easy to use application which is created to manage the employee data. It is created to record the details of the employees. This reduces the dependency on the manual system which could create errors. This system can easily help in tracking employee records.