选择运营商的计划

Question

    import java.util.*;
class calc123
{
    public static void main()
    {
        int a,b,c;
        char a1;
        Scanner sc=new Scanner(System.in);
        System.out.println("Enter first number");
        a=sc.nextInt();
        System.out.println("Enter second number");
        b=sc.nextInt();
        System.out.println("Enter the operator");
        a1=sc.next().charAt(0);
        if(a1="+")
        System.out.println(a+b);
        else if(a1="-")
        System.out.println(a-b);
        else if(a1="/")
        System.out.println(a/b);
        else if(a1="*")
        System.out.println(a*b);
        else if(a1="%")
        System.out.println(a%b);
        else
        System.out.println("Invalid Operator");
    }
}

面临的问题是（a1 =＆＃34; +＆＃34;）

incompatible types: java.lang.String cannot be converted to char. 

Answer 1

（a1 =“+”）不会返回true或false，它将返回“+”!,请提高您对Java的基本知识。另请注意，a1是char类型，而“+”是String。