二次公式是错误的，我不知道如何修复

Question

错误：

File: F:\lab_2.java  [line: 36]
Error: next cannot be resolved or is not a field
File: F:\lab_2.java  [line: 38]
Error: next cannot be resolved or is not a field
File: F:\lab_2.java  [line: 40]
Error: next cannot be resolved or is not a field
File: F:\lab_2.java  [line: 42]
Error: Duplicate local variable outa 

代码：

   else if (choice==1){
          int a;
          int b;
          int c;
          System.out.println("what is a ?");
          a=myscan.next ;   //line 36
          System.out.println("what is b ?");
          b=myscan.next ;   //line38
          System.out.println("what is c ?");
          c=myscan.next ;   //line40
       double outa =(b + Math.sqrt((b*b)-4*a*c))/(2*a);
       double outa =(b - Math.sqrt((b*b)-4*a*c))/(2*a);   //line42
       }
          //quadratic formula ^^^^

Answer 1

错误意味着“next”不是变量myscan上的有效方法或字段，我假设它是一个扫描程序。 如果“myscan”是一个扫描仪，我认为你正在寻找输入，所以：

a=myscan.nextInt();

另外，你将b +和b-分配给outa，所以你用第二个答案覆盖第一个答案。