Question

For this exercise, we are going to take a look at an alternate Calculator class, but this one is broken. There are several scope issues in the calculator class that are preventing it from running. Your task is to fix the Calculator class so that it runs and prints out the correct results. The CalculatorTester is completed and should function correctly once you fix the Calculator class.
public class Calculator {
private int total;
private int value;
public Calculator(int startingValue){
int total = startingValue;
value = 0;
}
public int add(int value){
int total = total + value;
return total;
}
/**
* Adds the instance variable value to the total
*/
public int add(){
int total += value;
return total;
}
public int multiple(int value){
int total *= value;
return total;
}
public void setValue(int value){
value = value;
}
public int getValue(){
return value;
}
}

Answer 1

Answer:

public class Calculator {

   private int total;

   private int value;

   

   public Calculator(int startingValue){

       // no need to create a new total variable here, we need to set to the our instance total variable

       total = startingValue;

       value = 0;

   }

   public int add(int value){

       //same here, no need to create a new total variable. We need to add the value to the instance total variable

       total = total + value;

       return total;

   }

   /**

   * Adds the instance variable value to the total

   */

   public int add(){

       // no need to create a new total variable. We need to add the value to the instance total variable

       total += value;

       return total;

   }

   public int multiple(int value){

       // no need to create a new total variable. We need to multiply the instance total variable by value.

       total *= value;

       return total;

   }

   //We need to specify which value refers to which variable. Otherwise, there will be confusion. Since you declare the parameter as value, you need to put this keyword before the instance variable so that it will be distinguishable by the compiler.

   public void setValue(int value){

       this.value = value;

   }

   public int getValue(){

       return value;

   }

}

Explanation:

I fixed the errors. You may see them as comments in the code