CODEWITHSUNDEEP
javaoopinheritance
gazubi
gazubi

Reputation: 561

In Java, how do I call the method of a overridden class from an instance of the overriding class

I am new to Java Inheritance. Please see the code for my parent class called Term:

public class Term {

  public String value;
  public void setValue(String value)
  {
    this.value=value;
  }

  public String getValue()
  {
    return value;
  }

}

Now class OperatorTerm extends Term

public class OperatorTerm extends Term {

  public static Operator type;

  public static boolean equals(String value)
  {
    String regex="(\\++)|(-+)|\\*|/";
    boolean isOperand=value.matches(regex);
    return isOperand;
  }

  public void assignType(String value)
  {
    if(value.equals("+"))
      type=Operator.ADD;
    else if(value.equals("-"))
      type=Operator.SUBTRACT;
    else if(value.equals("*"))
      type=Operator.MULTIPLY;
    else if(value.equals("/"))
      type=Operator.DIVIDE;
    else if(value.equals("++"))
      type=Operator.INCREMENT;
    else
      type=Operator.DECREMENT;
    }
  }

I am creating an OperatorTerm object like this in another class:

public static Term getTerm(String termValue)
{
  Term newTerm=null;
  if(ValueTerm.equals(termValue))
    newTerm=new ValueTerm();
  else if(ReferenceTerm.equals(termValue))
    newTerm=new ReferenceTerm();
  else if(OperatorTerm.equals(termValue))
  {
    newTerm=new OperatorTerm();
  }
  return newTerm;
}

In the last elseif statement, I want to do the following newTerm.assignType. assignType is a method in the OperatorTerm class but it is not present in the Term class. I am unable to do so, and I am wondering if someone can guide me on how can I use newTerm to access the methods of OperatorTerm class

I am creating an object of the overridden class using

Upvotes: 1

Views: 73

Answers (3)

hacksoi
hacksoi

Reputation: 1399

else if(OperatorTerm.equals(termValue))
{
    newTerm = new Operatorterm();
    ((OperatorTerm) newTerm).assignType(value);
}

Personally, I would do

else if(OperatorTerm.equals(termValue))
{
    OperatorTerm ot = new OperatorTerm();
    ot.assignType(value);
    return ot;
}

And do the same for the others.

Upvotes: 0

htobon
htobon

Reputation: 153

If you need to call the method "newTerm.assignType" inside the getTerm method only, perhaps you just need to return and/or create the proper child objects:

public static Term getTerm(String termValue)
    {
        // Term newTerm=null;
        if(ValueTerm.equals(termValue))
            return new ValueTerm();
        else if(ReferenceTerm.equals(termValue))
            return new ReferenceTerm();
        else if(OperatorTerm.equals(termValue))
        {
            OperatorTerm newTerm=new OperatorTerm();
            newTerm.assignType("+");
            return newTerm;
        }
        // return newTerm;
    }

As a rule, you cannot use methods created in extended classes if the object that you are using is the parent one.

Hope my answer is useful for what you want to do.

Upvotes: 0

ajb
ajb

Reputation: 31689

    else if(OperatorTerm.equals(termValue))
    {
        OperatorTerm newOperatorTerm = new OperatorTerm();
        newOperatorTerm.assignType(...);
        newTerm = newOperatorTerm;
    }

Upvotes: 3

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