Question

这是我的代码

class Base
{
  public void fillRandomData()
  {
    //code for accessing members for sub classes
        //here object "b" is calling this method
        //I want to access members of caller object
        //As it is Derived class how can I access its member 
  }
}

class Derived extends Base
{
  Map<String, List<Integer>> fields = new HashMap<String,List<Integer>>();
  List<Integer> attribute = new ArrayList<Integer>();

    public Derived() {
        attribute.add(1);
        fields.put("textbox",attribute);
    }
}

class Main
{
     public static void main(String[] argv) {
         Base b = new Base();
       **b.fillRandomData();**
     }
}

以上代码解释了我的问题。我被困在访问调用者对象成员我认为回顾会有所帮助但它并没有给我很多帮助。

在ruby中有方法＆＃34; instance_variable_get（instance_var）＆＃34;允许访问调用者对象的数据成员。

Answer 1

你必须定义方法并调用你的方法，你不能在类块中调用方法。

像这样：

class Main
{
void callMethod(){
  Base b = new Base ();
  b.fillRandomData();
}
}

Answer 2

根据我从你的问题中理解你想做的事情：

class Base
{
  public void fillRandomData()
  {
      // do not directly access members. you can use reflect to do this but do not do this.
      // (unless you have a real reason for it)
      //
      // instead, trust on the subclasses to correctly override fillRandomData to fill in the
  }
}

class Derived extends Base
{
    Map<String, List<Integer>> fields = new HashMap<String,List<Integer>>();
    List<Integer> attribute = new ArrayList<Integer>();

    public Derived() {
        attribute.add(1);
        fields.put("textbox",attribute);
    }

    @Override
    public void fillRandomData() {
         // in Main, the b.fillRandomData will run this method.

         // let the Base class set it's part of the data
         super.fillRandomData();

         // then let this class set it's data
         // do stuff with attributes
         // do stuff with fields.
    }
 }

class Main
{
  // you _must_ instantiate a derived object if you want to have a chance at getting it's instance variables
    public static void main(String[] argv) { 
        Base b = new Derived();
        b.fillRandomData();
    }
}

如何通过JAVA中的被调用方法访问调用者对象的成员

2 个答案: