Constructor Detail

• ExpressionTree

  public ExpressionTree(String operator,
                ExpressionTree left,
                ExpressionTree right)

  Constructs an expression tree using the given operator at the root, and the given expression trees as subexpressions. The left and right parameters are destroyed by this operation.

  Parameters:

  operator - presumed to be "+", "-", "*", or "/"

  left - representation of the left subexpression

  right - representation of the right subexpression

  Throws:

  IllegalArgumentExpression - if operator is not "+", "-", "*", or "/"

• ExpressionTree

  public ExpressionTree(String literal)

  Constructs an expression tree representing a single literal. The literal is presumed to be numeric.

  Parameters:

  literal - a valid numeric string

  Throws:

  NumberFormatException - if literal invalid

Method Detail

• evaluate

  public double evaluate()

  Returns the numeric result of the expression.

• toString

  public String toString()

  Produce a parenthesized string representation of the expression.

  Overrides:

  toString in class Object

• parseExpression

  public static ExpressionTree parseExpression(String raw)

  Returns an expression tree corresponding to a fully-parenthesized string, such as "(((3+1)*4)/((9-5)+2))

• main

  public static void main(String[] args)