I need to convert infix To Postfix but have a few errors.
Error msg:
PostFix:
Exception in thread "main" java.util.EmptyStackException
at java.util.Stack.peek(Unknown Source)
at java.util.Stack.pop(Unknown Source)
at assignment4.infixToPostfix.evaluatePostfix(infixTo Postfix.java:129)
at assignment4.infixToPostfix.main(infixToPostfix.jav a:19)
NB:
129 >>return (double) s1.pop(); AND 19>>>double ans = evaluatePostfix(postfixStr);
Deadline = less than 1 hour
Case study : infix to postfix conversion, i don't really know how i could make codes, I can understand what is the meaning of infix and postfix but when it comes of making codes i really have a hard time with it.
So my code works perfectly when I input (a+(c-d) and i get ab+cd- for postfix and *+ab-cd for prefix. However when I input a+b+c for infix i receive abc++ postfix and +a+bc prefix when its supposed to be ab+c+ postfix and ++a b c prefix. So my issue is that any infix input with parenthesis, it converts them correctly, however without parenthesis it does not convert correctly.
import java.util.*; public class stack { public static char[] convertToPostfix(char[] infixEx) { Stack<Character> operatorStack = new Stack<Character>(); char[] postfix = new char[infixEx.length]; int index = 0;
So I am supposed to be changing infix notation to postfix notation using stacks. This is simply taking a string "3 + 5 * 6" (infix) and turning it into (3 5 6 * +" (postfix).
To do this, we are to scan the string from left to right and when we encounter a number, we just add it to the final string, but when we encounter an operand, we throw it on the stack. Then if the next operand has a higher input precedence than the stack precedence of the operator on the top of the stack, we add that operator to the stack too, otherwise we pop from the stack THEN add the new operator.
I am supposed to be utilizing a hash map but I don't see how you would go about doing this. We are supposed to store operators on the hash map but operators need their own character, input precedence, stack precedence, and rank. How do you use a hash map when you need to tie a character to 3 values instead of just 1? I just don't get it.
The following is our Operator class that we are to use. Another problem is this isn't really supposed to be modified, yet we were given two important variables (inputPrecedence and outputPrecedence) that we can't have nothing to be initialized to and no way of accessing? So that might be where a hash map comes in but I am not sure. I am not very sure on how they exactly work anyway...
public class Operator implements Comparable<Operator> { public char operator; // operator privateint inputPrecedence; // input precedence of operator in the range [0, 5] privateint stackPrecedence; // stack precedence of operator in the range [-1, 3]
[Code] ....
So my question mostly revolves around how I tie an Operator character to its required values, so I can use it in my code to test two operators precedence values.
My original thought was turn string into character array, but then I would need nested for/while loops to check if it is a number or letter, or if it is an operator and thus result in O(n^2) time
I am given the task to create a program that evaluates infix expressions using two generic stacks, one operator stack and one value stack.
This is my GenStack.java file:
import java.util.*; public class GenStack<T>{//T is the type parameter private Node top;//top of stack public class Node {//defines each node of stack T value; Node next;
[Code] ....
I'm having trouble with the eval and apply methods. The eval method doesn't appear to pickup ')' characters, like it doesn't even see them.
So I am working on a PostFix calculator that is used in command line for a class project, and I am having a little trouble on developing a memory for it. I have been told to create a hashMap and I have researched it and understand the basics of it. I have the calculating method working, but what I am having trouble trying to implement a way for the user to declare variables. For example this what the user should be able to do:
> a = 3 5 + 1 - 7 > bee = a 3 * 21 > a bee + 28
[code]....
I just need to be able to save the answers as a variable the User names, such as the example and let the user be able to use the variables later.
after i am done calculating everything from numbers stack, i pop the last number and return it... my question is how can i catch an exception if the size of my numbers stack is greater than 1;
public static String evaluate(String input) { char[] a = input.toCharArray(); if (input.isEmpty()) return "No input"; else if (input.equals(" ")) return "No input"; else if (input.equals(" "))
My question is to evaluate a Postfix notation entered from keyboard. I have no errors in my code but it prints only :
Exception in thread "main"
java.util.NoSuchElementException at ArrayStack.pop(PostFixEvaluation.java:72) at PostFixEvaluation.evaluatePostfix(PostFixEvaluatio n.java:107) at PostFixEvaluation.main(PostFixEvaluation.java:140)
I tried many values but it prints the same exception all the time.
My verify method also always returns false. So I'm given three classes to begin with. Calculator, Expression, and InfixExpression and they are listed below.
The goal is to create a class called PostfixExpression that extends Expression and can read and calculate postfix expressions.
My evaluate() method works for most calculations but when it needs to return a negative value it just returns the positive equivalent.
Also, my verify method always returns false and I can't pinpoint why.
Here's my current code. Some things are commented out for debugging purposes.
import java.util.Scanner; /** * Simple calculator that reads infix expressions and evaluates them. */ public class Calculator { public static void main(String[] args) { Scanner input = new Scanner(System.in);
import java.util.Scanner; import java.util.Stack; public class stack { public static Integer evaluate(String expression) { Scanner scanner = new Scanner(expression); Stack <Integer> operands = new Stack<Integer>();
[Code] ....
When I input my expression which has spaces between characters e.g.:10 2 8 * + 3 -, it worked; when I put expression which may not add space between each char e.g.: 3 14+2*7/, the error showed:
Enter a postfix expression: 3 14+2*7/ Exception in thread "main" java.util.EmptyStackException at java.util.Stack.peek(Stack.java:102) at java.util.Stack.pop(Stack.java:84) at hw9.stack.evaluate(stack.java:22) at hw9.stack.main(stack.java:45)
public test5 { public boolean test(int grille[][]){ for (int i = 0 || i < grille.length || i++){ int max = grille[i][0]; for (int e = 1 || e < grille[i].length || j++){ if (grille[i][e]== max && max !=0){ solution = false; System.exit(1);
I get quite a few errors while trying to compile the BeerSong from the Head First Java book. I copied the text from another person that did the beer song on this forum and it worked as expected. What I can't figure out is why mine is not working when it looks like the text is exactly the same between the two versions. His works, but mine doesn't.
Here is the text and errors that I get:
public class BeerSong { public static void main (String[] args) { int beerNum = 99; String word = "bottles";
I am making a simple mod/hack for a game programmed in Java. I located the .class file I needed and deobfuscated it and then decompiled it. After that I went in and made a very simple adjustment that I wanted to make. Unfortunately I can across a problem when trying to compile the file! The file won't compile because there are errors. The reason there are errors is because this is just one file out of an entire game. I know this my seem weird, but is there some way I can compile the file with the errors.
I have the following code snipet and I get the following errors
interface expected here [javac] private class fileFilter implements FileNameExtensionFilter{ [javac] ^ cannot find symbol [javac] symbol : method fileFilter(java.lang.Object) [javac] location: class gui.components.StartupDialog
import javax.swing.*; public class opt { public int code[]; public static void main(String[] args) { int xxx = 1;
[Code] ....
Where did I did wrong cus I keep getting these errors: What do I need to do to fix the errors?
F:>javac opt.java opt.java:25: error: cannot find symbol cd.checkDeclare<zz>; ^ symbol: method checkDeclare<String> location: variable cd of type code[] java:32: error: cannot find symbol
I'm trying to use a setter method to pick a random integer to be the MPG for a car. However, I'm having major issues in my driver when trying to use that random number in an instance. I'm not finished with the driver yet because I keep getting "cannot find symbol errors"
import java.util.Random; public class Car { private String make; private String model; private int year; private int mpg; private int odometer; Random generator = new Random();
I am watching BrandonioProductions on youtube. His videos are pretty good, but he doesn't seem to get errors where I get them. Here is an example.
public class compareUnequal { public static void main(String[] args){ compareTwo(); } public static void compareTwo(){ String x = "david"; String y = "Notdavid"; if (!x.equals(y)){ System.out.println("Not equal"); } } }
It runs ok, but asked me to proceed when there is an error, but I can`t figure out where the error is!
Here is my code that is supposed to read a user-selected document, create text boxes from that info, and display them. (There is a lot of code in there that may not be relevent, but just ignore that.) When I compile, I receive errors that it can not find the symbols color, xIn, yIn, w, and h.
Here's my code:
import javax.swing.*; import javax.swing.event.*; import java.awt.*; import java.awt.event.*; import java.util.*; import java.io.*; public class Ex22 extends Basic {
I'm trying to read lines from a textfile and count all the words using String Tokenizer. However I keep getting an error "Unhandled exception type FileNotFoundException" on my IDE(Eclipse) referring to lines 13 and 8. When I let the IDE automatically, and I've even tried typing this manually, insert a try-catch block more errors show up concerning inputFile. When I insert the throws FileNotFoundException for each method it compiles but after running it gives me a FileNotFoundException for textfile.txt. What's even more interesting is that when I copy the .java file out of the IDE project folder, place it in a random empty folder on the Desktop with the textfile.txt, and try running it through command line, it gives a NoSuchElementException: No line found.
I have a JSP which will let a user register for an account at my website. If the user submits wrong or illegal info into the JSP, then I want to return the same JSP with an appropriate error message next to/above each wrongly filled (form) fields.
If possible, highlight the wrongly filled form field - this feature is not necessary though.
I have given a sample below to show what I need. I understand that the sample must be using something like javascript, but I don't know all that client side scripting. I only want to use JSP to do it. As I said, I want to sort of return the JSP form to the user after marking all the mistakes and how to correct them.
for my assignment I am to only add the sort and total inventory methods in the inventory class. And not create an array in the inventory class at all. My inventory class should contain all the variables needed to use with the two new methods: sort and calculate total inventory.By not creating any array in the inventory class and not touching the variables at all.For the inventoryTest class, I only need to declare an array of the inventory class by making an instance of the inventory.
public class inventory {
private int prodNumber; // product number private String prodName; // product name private int unitsTotal; // total units in stock private double unitPrice; // price per unit private double totalInventory; // amount of total inventory
