Simple Calculator using Servlet
Nov 04, · Step 1: – Create a blank Java project and name it Java Calculator. Uncheck the Main class option from the project tab. Step 2: – To add a Jframe, right click the project name in the Project window. Step 3: – To the right of the Jframe, there is a Palette with a set of controls on it. Dec 04, · Netbeans IDE; A pen and a paper(optional) Step 1: Create an Application in Netbeans. Name the application CalculatorProgram. If you don’t know how to create new application. You can get it here: Your First Java Program. Step 2: Add a JFrame Form to the Application.
After the "Hello World! The reason for this is because of the simplicity of its structure in addition to covering most of the basic concepts in programming. Follow the steps below and you too will be able to build your own fully functioning calculator!
All software programs are written on Development Environments, programs made specifically to build and compile software. For the programming language we're using, Java, the program Dr. Java is an excellent and simple introductory program to use. Start by downloading the program from www. After you first open Dr. Java, you'll be greeted with a blank screen of nothing. So beautiful and pristine, we're going to cover this baby with a lot of code. Start off by declaring a public Calculator class and then inside of it, a main method, exactly like shown in the picture.
In Java, a class is simply an object which holds information. In our case, the object we're building is a calculator so we have named it as such. A method is a process which performs a certain task. All methods follow the IPO structure as we will learn later. Brackets in java denote what is contained in what. In our example, our calculator object contains the method we are going to build. The brackets of the method is where our code is going to be contained.
As mentioned in the last step, all methods follow the IPO structure, short for input, process, output structure. This means that in short all methods receive some form of input, perform a process, and return an output.
First we're going to declare the inputs. Inputs can be of different data types so we have to be specific in our declaration. The main data types are int i.
For our example we need to declare two int type numbers and a char type operator which will signify the operation we want to perform. Also one thing we must note are the use of semi-colons. In coding these serve almost as periods and signify breaks in line for the computer reading the code. Now we begin the process portion of the how to connect cell phone internet to pc. The first thing we must build is a method for the user to enter whatever type of input we like.
We can achieve this with the use of a scanner which stores any data the user types how to remove concrete from brick an assigns it to the inputs we declared previously. We import the scanner object top linedeclare one for use, and then type three lines asking the user for input and then assigning those values.
We need to declare a value where our output value is stored. We'll use a double type in case the answer is not a whole number. For the last portion of the process section, we must make a switch statement. The switch receives the what is normal temperature and pressure variable and depending on what it is, chooses a certain case. Now that our code is complete, we must compile or build the code. Save the program in whichever location is best for you.
Question 3 months ago. But I have already clicked on compile a lot of times! Tell me what's wrong with my coding please? Question 1 year ago. Answer 1 year ago. You used a lowercase o instead of the capital O like in the how to create a calculator in java using netbeans images.
Also, your syntax is incorrect at the end, which might throw another error. The final curly bracket should be on its own line. Question 2 years ago. Question 1 year ago on Step 4. Scanner; I am using eclipse IDE my code is not returning points to the line above as the error anyone kinkly help me. The way you have your double setup for answer the program will always return a decimal number with. To fix this initialise num1 and num2 as doubles also.
Very cool! I've never done much with Java. Looks very similar however. Reply 5 years ago. Glad you enjoy! Finally we how to prevent damage from volcanoes to declare a line to display the output of our calculator. Did you make this project? Share it with us! I Made It! Answer Upvote. Reply Upvote. LeandrosP Question 1 year ago. Can someone help me cause I can't seem to understand what's the issue.
GabrielB45 LeandrosP Answer 1 year ago. What does the operator do? What does. What does char at 0 find our at first? MaryN69 Question 1 year ago on Step 4. AnthonyP 2 years ago. Error when running the program. Forgot to close the scanner program. StudentMem 2 years ago.
RugbyLad99 2 years ago on Step 9. When I click compile it just comes up with random errors that I didn't even make?
Apr 13, · How to Create Calculator in Java NetBeans Full Tutorial, using If Statement'Join this channel to get access to codes, perks, and see more interesting videos. In This Java Tutorial we will See How To Make A Calculator With Swith To Do The Basic Operations (Addition, Subtraction, Multiplication, Division) And Clear Text Number By Number And Reset To Make Another Calc Using Netbeans Editor. JAVA Tutorials: JTable Rows To Txt File. Text File Data To JTable. Get Date From JTable And Show It In JDateChooser. Dec 05, · November 5, This is the Part 2 of How to Build a Simple Calculator in Java using Netbeans IDE. This part follows from the first part. If you have not gone through the first part, you can find it in the link below: Part 1: How to Build a Simple Calculator in Java Using Netbeans – Step by Step with Screenshots.
It'll look like this:. Create a new project Java Application without the main class named Calculator. In Properties, set the title to Calculator. When creating applications, we usually start with the form design.
Let's drag several components onto the form from the palette. We'll need:. If we don't use components from the code, we don't have to name them. If so, we should rename them see below and then we access the component by this name from the code. We already know the text property. It contains what is displayed in the label.
So, set it up. We'll use the second label to display the result. Since we'll set its value by the program, we'll rename it to resultJLabel with the capital letter J. To do this, right-click the label and choose Change Variable Name A button is simply a component that calls a method when clicked more precisely triggers an event.
In our case, the button will be named calculateJButton and its text will be Calculate. We'll assign the event to the button later. Spinner is the first component to enter a value that we'll mention. We can enter a whole number in it and also a decimal number if we enable it. The advantage of entering numbers with this component is that the user can't enter an invalid value.
If we parsed the number from a Text Field we'll show these in the following lessons , our application might crash due to invalid input. It's always easier to choose the right component than to validate the user input.
We'll name the components as number1JSpinner and number2JSpinner. Note that the name should always contain the component type as well.
Like that, it's possible to have, for example, both ageJLabel and ageJSpinner , where the label is the description of the field serving to enter an age and the spinner is then that field.
Moreover, our code is then much clearer. Names such as numberSpn , calculateBtn and so on are sometimes used as well. We're almost finished. Combo Box is a drop-down list with several predefined elements. The elements can either be added in the designer or from the code, even at runtime. This applies to all components, we can set all properties found in the designer from the code as well. Let's name the component operationJComboBox and click on the " In the newly opened window, we'll list the options to choose from in the Combo Box.
We can set the default selected item with the selectedIndex property, 0 is the first value. So we just have to respond to the button click event. Click the button twice, and a new method will be generated in our code:. When we expand the generated initComponents method, we find the button with a few lines setting its ActionListener. This is an object that can respond to an action a click on the button in our case and calls the above method. If you've finished reading our course on object-oriented programming, you should know this is an anonymous class.
If not, it doesn't matter at all. The key is that you have an idea of how the connection between the component and the click-handling method is created. Let's go back to the designer the Design button in the top bar and select the button.
In the Properties window, you can switch between Properties and Events the Properties and Events buttons. Here we can see our actionPerformed event this is the click event. We could remove it from here and possibly add it again. Some components have special events for which we generate methods from here.
Never remove events by deleting the handler method from the code, the designer would stop working, and you would have to correct the file specifically, remove the line with the registration of a non-existent method to the event.
While NetBeans will not allow you to do this, it's possible to delete it e. The only right way is through the designer. Let's proceed to the calculation itself. The code won't be complicated. In the handler method, we'll simply use if statements for the selected item of the operationComboBox and calculate the result accordingly.
Then we'll set the result as the text of resultJLabel. We shouldn't forget to handle the division by zero. In our case, we have to convert it to String. We could also work just with the numeric index of the item using getSelectedIndex.
Since Spinner returns the value as an Object type, we must cast it to int. It contains the showMessageDialog method. Finally, we pass the result to resultJLabel. Unlike the console, where numbers could be simply printed out, here we must first convert the number to String.
If we turn off the resizable property in the Properties window, it won't be possible to resize the window, which is useful for our application. This app may already be worth sending to someone.
This is an executable file for your application. Of course, you must have Java installed to run it. But most people have it. The project source code is attached to the article as always.
The next time, Birthday Reminder in Java Swing - Form design , we'll create a more complex application with multiple forms. It'll be a birthday reminder.
Did you have a problem with anything? Download the sample application below and compare it with your project, you will find the error easily. Downloaded 45x Only this week! More info. Login Register. Master Form Applications in Java Swing! Just click the button below to start the whole online course! Previous article Java Swing under the hood.
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