Implement the following expression tree in JAVA that works with an expression th
ID: 3595935 • Letter: I
Question
Implement the following expression tree in JAVA that works with an expression that contains only variables or double values and supports operations +, -, *, and / by providing two additional methods: void setVariable(String name, double value) – set the variable name with a value with exception handling;package TreePackage;
Could you help me to solve this problem? I wrote the following code, but it doesnt work correctly.
Sample usage:
ExpressionTree expr = new ExpressionTree(new String[]{"a", "b", "2", "/","+"});
expr.setVariable("a", 1.5);
expr.setVariable("b", 2);
System.out.println(expr.evaluate());
public class ExpressionTree extends BinaryTree<String>
implements ExpressionTreeInterface
{
public ExpressionTree()
{
} // end default constructor
public double evaluate()
{
return evaluate(getRootNode());
} // end evaluate
private double evaluate(BinaryNode<String> rootNode)
{
double result;
if (rootNode == null)
result = 0;
else if (rootNode.isLeaf())
{
String variable = rootNode.getData();
result = getValueOf(variable);
}
else
{
double firstOperand = evaluate(rootNode.getLeftChild());
double secondOperand = evaluate(rootNode.getRightChild());
String operator = rootNode.getData();
result = compute(operator, firstOperand, secondOperand);
} // end if
return result;
} // end evaluate
private double getValueOf(String variable)
{ // Strings allow multicharacter variables
double result = 0;
if (variable.equals("a"))
result = 2;
else if (variable.equals("b"))
result = 3;
else if (variable.equals("c"))
result = 4;
else if (variable.equals("d"))
result = 5;
else if (variable.equals("e"))
result = 2;
return result;
} // end getValueOf
private double compute(String operator, double firstOperand, double secondOperand)
{
double result = 0;
if (operator.equals("+"))
result = firstOperand + secondOperand;
else if (operator.equals("-"))
result = firstOperand - secondOperand;
else if (operator.equals("*"))
result = firstOperand * secondOperand;
else if (operator.equals("/"))
result = firstOperand / secondOperand;
return result;
} // end compute
// For testing purposes
public void displayTree()
{
BinaryNode<String> rootNode = (BinaryNode<String>)getRootNode();
System.out.println("preorder:");
preorder(rootNode);
System.out.println();
System.out.println("postorder:");
rootNode = (BinaryNode<String>)getRootNode();
postorder(rootNode);
System.out.println();
} // end displayTree
private void postorder(BinaryNode<String> rootNode)
{
if (rootNode != null)
{
postorder(rootNode.getLeftChild());
postorder(rootNode.getRightChild());
System.out.print(rootNode.getData() + " ");
} // end if
} // end postorder
private void preorder(BinaryNode<String> rootNode)
{
if (rootNode != null)
{
System.out.print(rootNode.getData() + " ");
preorder(rootNode.getLeftChild());
preorder(rootNode.getRightChild());
} // end if
} // end preorder
} // end ExpressionTree
Explanation / Answer
Could you please share the enitre code ?
I see the package and class is missing