Using methods and constructors to construct a basic calculator I am trying to come up with a simple basic calculator but am supposed to work with the following constructors and methods:

simpleCalc();
simpleCalc(double op1, double op2);
double add();
double add(double op1, double op2);
double mult();
double mult(double op1, double op2);
double exp();
double exp(double op1, double op2);
void show();
void show(int dp);


I have written down some working code and I just want to know if am doing the right thing.

MyClass.java

package basicjavacalculator;

public class MyClass {
public static void main(String[] args) {
// TODO code application logic here
simpleCalc sc = new simpleCalc();
sc.show();

 }

}


simpleCalc.java

package basicjavacalculator;

import java.util.Scanner;

public class simpleCalc {

double add(){
return 0;
}

double mult(){
return 0;
}

double exp(){
return 0;
}

simpleCalc(){

}

void show(){

Scanner userInput = new Scanner(System.in);

System.out.println("=================Welcome to SimpleCalcDemo=================");
System.out.println("\n");

System.out.println("Enter first number: ");
double op1 = userInput.nextInt();

System.out.println("Enter second number: ");
double op2 = userInput.nextInt();

System.out.print("Enter operation to perform (+,x,^):");
String operation= userInput.next();

if(operation.equals("+")){
    System.out.println(add(op1, op2));
}

else if (operation.equals("x")){
    System.out.println(mult(op1, op2));
} 

else if (operation.equals("^")){
    System.out.println(exp(op1, op2));
}
else{
System.out.println("The operation is not valid.");

}

}

double add(double op1, double op2){
return op1 + op2;
}

double mult(double op1, double op2){
return op1 * op2;        
}

double exp(double op1, double op2){
double result = 1;
while (op2 &gt; 0){
    result = result * op1;
    op2--;
}

return result;
}

}
This can be simplified:

double exp(double op1, double op2){
double result = 1;
while (op2 &gt; 0){
    result = result * op1;
    op2--;
}

return result;
}


You should be using the Math.pow() method:

double exp(double op1, double op2){
    return Math.pow(op1, op2);
}


Also, you should use proper indentation to help you read and understand your code better, which will help prevent bugs.

This doesn't do anything:

simpleCalc(){

}


It is best to remove code like this to make your project easier to understand and maintain.