Question

我是编程的初学者。我认为问题出现在writeOutput中，因为当我尝试从readInput中添加.getsum时，它可以工作。 general output 这是我的代码

import java.util.Scanner;
public class Calculator {
int userInput;

public void readInput(){
Scanner sc = new Scanner(System.in);    
Addition add = new Addition();
Subtraction sub = new Subtraction();
Multiplication prod = new Multiplication();
Division quo = new Division();

System.out.print("Pick what method you want to apply\n [1]Addition\n [2]Subtraction\n [3]Multiplication\n [4]Division\n: ");
userInput = sc.nextInt();


System.out.print("Enter number1: ");
int num1 = sc.nextInt();
add.setNumber1(num1);
sub.setNumber1(num1);
prod.setNumber1(num1);
quo.setNumber1(num1);
System.out.print("Enter number2: ");
int num2 = sc.nextInt();
add.setNumber2(num2);
sub.setNumber2(num2);   
prod.setNumber2(num2);  
quo.setNumber2(num2);


}

public void writeOutput(){
    Addition add = new Addition();
    Subtraction sub = new Subtraction();
    Multiplication prod = new Multiplication();
    Division quo = new Division();

我无法上班。它总是等于零。

    if(userInput == 1){
        System.out.println("The Sum is " + add.getSum());
    }
    else if(userInput == 2){
        System.out.println("The Difference is " + sub.getDifference());
    }
    else if(userInput == 3){
        System.out.println("The Product is " + prod.getProduct());
    }
    else if(userInput == 4){
        System.out.println("The Quotient is " + quo.getQuotient());
    }
    else{
    }
}


public static void main(String[] args) {
    Calculator calc = new Calculator();

    calc.readInput();
    calc.writeOutput();

}
}

Answer 1

在进行输出时，您正在创建新对象。创建每个Addition的实例，sub ...然后在输出中使用该对象或使其成为静态对象。

Answer 2

不是制作计算类的本地对象，而是制作这些实例变量，然后在两种方法中使用相同的变量，请尝试下面的代码段：

import java.util.Scanner;
public class Calculator {

    int userInput;
    Addition add = new Addition();
    Subtraction sub = new Subtraction();
    Multiplication prod = new Multiplication();
    Division quo = new Division();

    public void readInput(){
    Scanner sc = new Scanner(System.in);    

    System.out.print("Pick what method you want to apply\n [1]Addition\n [2]Subtraction\n [3]Multiplication\n [4]Division\n: ");
    userInput = sc.nextInt();

    System.out.print("Enter number1: ");
    int num1 = sc.nextInt();
    add.setNumber1(num1);
    sub.setNumber1(num1);
    prod.setNumber1(num1);
    quo.setNumber1(num1);
    System.out.print("Enter number2: ");
    int num2 = sc.nextInt();
    add.setNumber2(num2);
    sub.setNumber2(num2);   
    prod.setNumber2(num2);  
    quo.setNumber2(num2);
}

public void writeOutput(){

    if(userInput == 1){
            System.out.println("The Sum is " + add.getSum());
        }
        else if(userInput == 2){
            System.out.println("The Difference is " + sub.getDifference());
        }
        else if(userInput == 3){
            System.out.println("The Product is " + prod.getProduct());
        }
        else if(userInput == 4){
            System.out.println("The Quotient is " + quo.getQuotient());
        }
        else{
        }
    }


    public static void main(String[] args) {
        Calculator calc = new Calculator();

        calc.readInput();
        calc.writeOutput();

    }
}

无法从我的public void writeOutput中获取add.getSum（）等

2 个答案: