我正在尝试使用多个类来制作一个简单的计算器。我可以在一个班级中做一个班,但现在我想尝试使用两个班级制作一个班级。我无法从OperationClass调用一些变量(fnum,snum,answer)。 如果我现在编写程序时运行该程序,则返回0作为答案。 我试着让变量fnum,snum和在OperationClass public中回答,但没有奏效。 另外我试过公共类OperationClass extends Calculator。那也行不通。
我知道我很想念一件很简单的事情。我只是不能指出它。多级计算器
计算器类:
import java.util.Scanner;
public class Calculator{
public static void main(String[] args) {
OperationClass operationObject = new OperationClass();
Scanner input = new Scanner(System.in);
double userInput;
int userChoice;
System.out.print("Please Enter The First Number: ");
userInput = input.nextDouble();
System.out.print("Please Enter The Second Number: ");
userInput = input.nextDouble();
System.out.println("Please Select Operation to Perform:");
System.out.println("1-Addition");
System.out.println("2-Subtraction");
System.out.println("3-Division");
System.out.println("4-Multiplication");
userChoice = input.nextInt();
switch (userChoice){
case 1:
operationObject.addition();
System.out.println();
break;
case 2:
operationObject.subtraction();
break;
case 3:
operationObject.division();
break;
case 4:
operationObject.multiplication();
break;
}
}
}
OperationClass:
public class OperationClass{
double fnum, snum, answer;
public void addition(){
answer = fnum + snum;
System.out.println(answer);
}
public void subtraction(){
answer = fnum - snum;
System.out.println(answer);
}
public void division(){
answer = fnum/snum;
System.out.println(answer);
}
public void multiplication(){
answer = fnum * snum;
System.out.println(answer);
}
}
你没有初始化你的''OperationClass实例成员'FNUM,snum' ... – ericbn
当一个帖子把代码,选择整个代码,点击“{}”按钮的上方页。它会避免一些零件被遗漏。 –