title: How to iterate over a java class and use a hashmap to choose right method?
body: <p>Java noob here, i have a program that i want to iterate the number of plugins that has been added in another file, then as long as it's a prefix and postfix calculator i want to check if the symbol in the stack for example is '+' so find Addition class that extended from Operator class and then call doAction(stack.pop(), stack.pop()) , it's because i want to add unlimited methods for calculating more symbols
  i tried to use reflection but i couldn't understand how to loop over between names to let the program choose the right method</p>
  
  <pre><code>public class Operator {
      public int doAction(int op1, int op2) {
          return 0;
      }
  
      public String getOperator(String sign) {
          return null;
      }
  
      public String setOperator() {
          return null;
      }
  
  
  }
  
  class Plus extends Operator {
      public int doAction(int op1, int op2) {
          return op1 + op2;
      }
  
      public String setOperator() {
          return "+";
      }
  
      public String getOperator(String sign) {
          if (sign.equals("+")) {
              return "+";
          } else {
              return null;
          }
      }
  }
  
  class Minus extends Operator {
      public int doAction(int op1, int op2) {
          return op1 - op2;
      }
  
      public String setOperator() {
          return "-";
      }
  
      public String getOperator(String sign) {
          if (sign.equals("-")) {
              return "-";
          } else {
              return null;
          }
      }
  }
  </code></pre>