Target:
Simple calculator, design a calculator program that can perform basic mathematical operations (addition, subtraction, multiplication, and division).
1. Project overview and functional planning
Our goal is to create a simple and intuitive command line calculator. When the user enters two values and the required operation symbols (+, -, *, /) when the program is running, the calculator can quickly give accurate operation results. For example, if the user enters "3 + 5", the program should output "8". To achieve this function, we need to carefully plan the structure and logic of the program.
2. Code implementation steps
-
Get user input:use
ScannerClasses gracefully receive two numerical values and operator symbols entered by the user in the console. Here is the sample code:
public static void main(String[] args) {
Scanner sc=new Scanner();
("Please enter the first number:");
double num1=();
("Please enter the calculator (+,—, *, /):");
String op=();
("Please enter the second number:");
}In the above code,ScannerInstance of classscannerResponsible for reading user input.nextDouble()Method is used to obtain the value of the double-precision floating point number type.next()Then get the operator symbol entered by the user.
2. Execute the operation and output the result: Define a method, call a method, and use it skillfully based on user input operator symbols.if-elsestatement orswitchStatements to flexibly control the program's calculation process, perform corresponding mathematical operations and output the results. The sample code is as follows:
public class Demo101 {
public static void main(String[] args) {
Scanner sc=new Scanner();
("Please enter the first number:");
double num1=();
("Please enter the calculator (+,—, *, /):");
String op=();
("Please enter the second number:");
double num2=();
double result=calc(num1,op,num2);
(num2+" "+op+" "+num2+" = "+result);
}
public static double calc(double num1, String op, double num2) {
double result=0;
switch (op){
case "+":
result=num1+num2;
break;
case "-":
result=num1-num2;
break;
case "*":
result=num1*num2;
break;
case "/":
result=num1/num2;
break;
default:
("Please enter valid operator");
}
return result;
}In this code,switchStatements are based on user input operator symbolsopAccurately match the corresponding operation branches.
3. Testing and Optimization
After the code was written, I couldn't wait to test it. I entered various different combinations of numbers and operators to see if the program can calculate correctly. During the testing process, I found that if the divisor is zero, the program will report an error and I have to continue to optimize. In addition, if the user enters an operator that is not +, -, *, and /, the program will also prompt "Invalid operator!".
4. Summary and Reap
Through this experience of writing Java simple calculator, I have a deeper understanding and mastery of the basics of Java. From how to receive user input, to performing operations based on different conditions, to handling possible errors, I have learned a lot in every link. I found that programming is like building blocks, combining small functional modules to achieve a complete function. Moreover, in the process of encountering and solving problems, my programming and logical thinking skills have been greatly improved. Although this calculator program is still very simple, it is an important achievement in my Java programming learning path and has also made me full of confidence in learning more complex programming knowledge in the future. I believe that as long as I continue to learn and practice, I will definitely be able to write a better program!
Summarize
This is the end of this article about creating a simple calculator implementation with Java. For more related content of simple calculator, please search for my previous articles or continue browsing the related articles below. I hope everyone will support me in the future!