Compilation error.

[Tonks Gabriel]

I'm trying to make an arithmetic expression calculator based on input I put on the console. I keep getting the error below. Any ideas how to fix this.
"Exception in thread "main" java.lang.Error: Unresolved compilation problems:
The constructor ExpressionTree(String) is undefined
Syntax error on token "Calc", delete this token
The method evaluate() is undefined for the type String
at ExpressionTree$PrefixCalc.main(ExpressionTree.java:110)"

import java.util.*;
import java.io.*;
public class ExpressionTree {
	private static class TreeNode{
		private final boolean leaf;
		private final char op; 
		private double value; 
		private TreeNode left, right; 
	private TreeNode(boolean leaf, char op, double value){
		this.leaf=leaf;
		this.op = op;
		this.value = value;
		this.left = null;
		this.right = null;
	}
	public String toString(){ 
		return leaf ? Double.toString(value) : Character.toString(op);
	}
	}
	
	TreeNode root = null;
	public ExpressionTree (Scanner input){ root = build(input);}
	

	private TreeNode build(Scanner input){
		boolean leaf;
		String token;
		double value;
		TreeNode node;
		leaf = input.hasNextDouble();
		if(leaf){
			value= input.nextDouble();
			node = new TreeNode (leaf, '\0', value);
		}
		else{
			token = input.next();
			node = new TreeNode (leaf, token.charAt(0), 0.0);
			node.left = build(input);
			node.right = build (input);			
		}
		return node;
	}
	
	public void showPostFix(){
		showPostFix (root);
		System.out.println();
	}
	private void showPostFix(TreeNode node){
		if (node !=null){
			showPostFix(node.left);
			showPostFix(node.right);
			System.out.println(node+ " ");
			
		}
	}
	public void showPreFix(){
			showPreFix(root);
			System.out.println();
	}
	private void showPreFix(TreeNode node){
		while(node!=null){
			System.out.print(node + " ");
			showPreFix(node.left);
			node = node.right; 
		}
	}
	public void showInFix(){
		showInFix(root);
		System.out.println();
	}
	private void showInFix(TreeNode node){
		if(node != null){
			if(!node.leaf)
				System.out.print("( ");
			showInFix(node.left);
			System.out.print(node+ " ");
			showInFix(node.right);
			if(!node.leaf)
				System.out.print(") ");
		}
	}
	public double evaluate(){
		return root == null ? 0.0: evaluate (root);
	}
	private double evaluate( TreeNode node){
		double result;
		if(node.leaf)
			result = node.value;
		else{
			double left, right;
			char operator = node.op;
			left= evaluate(node.left);
			right= evaluate(node.right);
			switch(operator){
			case '-': result = left-right; break;
			case '*': result = left*right; break;
			case '/': result = left/right; break;
			case '^': result = Math.pow(left, right); break;
			
			case '+': result = left+right; break;
			}
		}
		return result;
	}
	public static class PrefixCalc{
		public static void main( String[] args){
			ExpressionTree Calc;
		    Scanner src = new Scanner(System.in);
			Calc= new ExpressionTree( src.nextLine());
			System.out.println("prefix expression");
			Calc.showPreFix();
			System.out.println("postfix expression");
			Calc.showPostFix();
			System.out.println("infix expression");
			Calc.showInFix();
			System.out.println("Value:" Calc.evaluate());
		}
	}
}

[dennis deems]

Compiler errors can sometimes be mystifying, but in this case it is telling you exactly what the problem is. You are passing a String into the ExpressionTree constructor. The constructor for that class doesn't take a String, however; it takes a different kind of object. Fortunately you do have what it needs close to hand. Check the constructor, then check how you try to invoke it.

[Winston Gutkowski]

Tonks Gabriel wrote:I'm trying to make an arithmetic expression calculator based on input I put on the console. I keep getting the error below. Any ideas how to fix this.
"Exception in thread "main" java.lang.Error: Unresolved compilation problems:
The constructor ExpressionTree(String) is undefined
Syntax error on token "Calc", delete this token
The method evaluate() is undefined for the type String
at ExpressionTree$PrefixCalc.main(ExpressionTree.java:110)"

The compiler message is quite explicit. It's telling you that your ExpressionTree class doesn't have a constructor that takes a String; and it doesn't.
The only one you've defined takes a Scanner.

Winston

[Tonks Gabriel]

Ok I have fixed it. I run it and inputted "(34*65)" in the console. It doesn't show anything. Any tips?

import java.util.*;
import java.io.*;
public class ExpressionTree {
	private static class TreeNode{
		private final boolean leaf;
		private final char op; 
		private double value; 
		private TreeNode left, right; 
	private TreeNode(boolean leaf, char op, double value){
		this.leaf=leaf;
		this.op = op;
		this.value = value;
		this.left = null;
		this.right = null;
	}
	public String toString(){ 
		return leaf ? Double.toString(value) : Character.toString(op);
	}
	}
	
	TreeNode root = null;
	public ExpressionTree (Scanner input){ root = build(input);}
	

	private TreeNode build(Scanner input){
		boolean leaf;
		String token;
		double value;
		TreeNode node;
		
		leaf = input.hasNextDouble();
		if(leaf){
			value= input.nextDouble();
			node = new TreeNode (leaf, '\0', value);
		}
		else{
			token = input.next();
			node = new TreeNode (leaf, token.charAt(0), 0.0);
			node.left = build(input);
			node.right = build (input);			
		}
		return node;
	}
	
	public void showPostFix(){
		showPostFix (root);
		System.out.println();
	}
	private void showPostFix(TreeNode node){
		if (node !=null){
			showPostFix(node.left);
			showPostFix(node.right);
			System.out.println(node+ " ");
			
		}
	}
	public void showPreFix(){
			showPreFix(root);
			System.out.println();
	}
	private void showPreFix(TreeNode node){
		while(node!=null){
			System.out.print(node + " ");
			showPreFix(node.left);
			node = node.right; 
		}
	}
	public void showInFix(){
		showInFix(root);
		System.out.println();
	}
	private void showInFix(TreeNode node){
		if(node != null){
			if(!node.leaf)
				System.out.print("( ");
			showInFix(node.left);
			System.out.print(node+ " ");
			showInFix(node.right);
			if(!node.leaf)
				System.out.print(") ");
		}
	}
	public double evaluate(){
		return root == null ? 0.0: evaluate (root);
	}
	private double evaluate( TreeNode node){
		double result;
		if(node.leaf)
			result = node.value;
		else{
			double left, right;
			char operator = node.op;
			left= evaluate(node.left);
			right= evaluate(node.right);
			switch(operator){
			case '-': result = left-right; break;
			case '*': result = left*right; break;
			case '/': result = left/right; break;
			case '^': result = Math.pow(left, right); break;
			default: System.out.print("Unrecognized operator" + operator + "treated as +.");
			case '+': result = left+right; break;
			}
		}
		return result;
	}
	public static class PrefixCalc{
		public static void main( String[] args){
			ExpressionTree Calc;
		    Scanner src = new Scanner(System.in);
			Calc= new ExpressionTree(src);
			System.out.println("prefix expression");
			Calc.showPreFix();
			System.out.println("postfix expression");
			Calc.showPostFix();
			System.out.println("infix expression");
			Calc.showInFix();
			System.out.println("\n Value:" +Calc.evaluate());
		}
	}
}

[Jeff Verdegan]

Tonks Gabriel wrote:Ok I have fixed it. I run it and inputted "(34*65)" in the console. It doesn't show anything. Any tips?

Do what the pros do: Either add a bunch of print statements or use a debugger, so that you can see which code is getting executed and what various relevant values are at each step.

[Tonks Gabriel]

Anyone know how to fix this?

java.util.Scanner[delimiters=\p{javaWhitespace}+][position=0][match valid=false][need input=false][source closed=false][skipped=false][group separator=\,][decimal separator=\.][positive prefix=][negative prefix=\Q-\E][positive suffix=][negative suffix=][NaN string=\Q?\E][infinity string=\Q?\E]

There was also a pop-up screen that it say obsolete method.