I am trying to learn some oop in java. What I am trying to do is building a binary tree to convert an ekspresion in reverse police notation to infix notation. The problem is that I have three classes, one abstract called ArithmeticNode which represents a general node, a class called ValueNode representing a leaf with no children and the last class called OperatorNode representing a node with two children.
ArithmeticNode
abstract class ArithmeticNode
{
protected Object data;
protected String infixNotation;
abstract Object printNode();
abstract String infix();
}ValueNode
class ValueNode extends ArithmeticNode
{
public ValueNode(Number value)
{
super.data = value;
}
public Object printNode()
{
return super.data;
}
public String infix()
{
super.infixNotation += super.data;
return super.infixNotation;
}
}OperatorNode
class OperatorNode extends ArithmeticNode
{
Object leftChild;
Object rightChild;
public OperatorNode(Object operator, Object LC, Object RC)
{
this.leftChild = LC;
this.rightChild = RC;
super.data = operator;
}
public String printNode()
{
String node = new String();
node = leftChild.toString();
node += super.data.toString();
node += rightChild.toString();
return node;
}
public String infix()
{
super.infixNotation += leftChild.infix();
super.infixNotation += super.data;
super.infixNotation += rightChild.infix();
return super.infixNotation;
}
}The problem I am having right now, is how do I know what the children in OperatorNode is an instance of. They can be both an OperatorNode or a ValueNode. Right now I have them as Object which does not work.
So the question is: is there a way to decide what instance each child is or do I need to restructure?
