How can I perform an operation on operands of unknown types?

• 0
  For example, let's take the operation +.
  
  You need a function like this:
  Object plus (Object left, Object right) {...}
  
  What:
  

  plus(1, 3); // = 4 (Integer)
  plus(1L, 3); // = 4 (Long)
  plus(1L, "test"); // = "1test" (String)
  plus(1, new Date()); // Exception

  Java Adalyn Wallace, Sep 5, 2020

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1 Answers
• 0
  Something like this:
  

  public class HelloWorld
  
  {
  
    public static void main(String[] args)
  
    {
  
      System.out.println(plus(1, 3));
  
      System.out.println(plus("one", 2));
  
  
  
    }
  
    public static Object plus(Object l, Object r){
  
      Object ret=null;
  
      if ((r instanceof Integer) && (l instanceof Integer)){
  
      	ret = (Integer)r+(Integer)l;
  
      }
  
      if ((r instanceof Integer) && (l instanceof String)){
  
      	ret =(String) r.toString()+l;
  
      }
  
      return ret;
  
    }
  
  }

  
  

  4
  
  2one

  Anonymous

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