Question

我是Java的新手，我有以下代码，并且像

一样获得异常

Exception in thread "main" java.lang.Error: Unresolved compilation problems: 
    Cannot instantiate the type Calculator2Service
    The method getCalculator2Port() is undefined for the type Calculator2Service

    at com.theopentutorials.ws.calc2.client.Calc2Client.main(Calc2Client.java:13)

请一位帮助..

package com.theopentutorials.ws.calc2.client;

import com.theopentutorials.ws.calc2.*; 

public class Calc2Client {

    /**
     * @param args
     */
    public static void main(String[] args) {
        int a = 10;         
        int b = 12;         
        Calculator2Service calcService = new Calculator2Service();         
        Calculator2 calc = calcService.getCalculator2Port();         
        System.out.println(a + " + " + b + " = " + calc.add(a, b));         
        System.out.println(a + " - " + b + " = " + calc.sub(a, b)); 

    }

}

Answer 1

您应该在班级getCalculator2Port中定义Calculator2Service。如果您确定已经完成了这项工作，请检查拼写并注意Java是一种区分大小写的语言。

顺便说一下，您可能希望访问getCalculator2Port，但在此范围内不可见，例如它是private方法，但在这种情况下，您会收到通知“方法......来自类型......不可见”。

Answer 2

Calculator2Port是一个工厂方法，它在这里返回一个Calculator2对象。您应该定义一个接口或抽象类，如

public interface Calculator2 {

    public double add(double a, double b);
    public double sub(double a, double b);
}

然后在Calculator2Service中应该有一个类似

的方法

Calculator2 getCalculator2Port(){
    Calculator2 c = new Calculator2(){
       public double add(double a,double b){
          return(a+b);
       }

       public double sub (double a, double b){
          return(a-b);
       }
    }
    return(c);
 }

无法实例化该类型

2 个答案: