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(" "))
[code]....
package hw9;
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)
I just wanted to ask that while evaluating any expression,is the operator precedence fixed or it varies according to the compiler ,?
View Replies View RelatedFor an assignment I need to read an input text file and evaluate the triangle based on the data found in the text file which consists of an unknown number of groups of 3 numbers (Each group representing a different triangle). According to the project specifications I need to have a main method and several other methods. I have the main method set-up to receive data correctly but I am confused as to how I would get the values out of the text file and use them in the main method. For example, if I were to call the computePerimeter method in my main method, how would I make sure I get the correct perimeter for the given data?
Here is the code I have so far:
import java.io.*;
import java.util.Scanner;
public class TriangleEvaluator
{
public static void main(String[] args) throws FileNotFoundException
{
Scanner in = new Scanner(new File("triangleData.txt"));
double s1;
double s2;
double s3;
while (in.hasNextDouble())
[Code] ....
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.
View Replies View RelatedSo 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.
Will the postfix x++ and the prefix --y change the answer for this question?
If x has the value 10 and so does y, then what is the value of (x ++) * (-- y)?
Answer: 11*9
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
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.
Here is my code:
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.NoSuchElementException;
interface Stack<E> {
[Code] ....
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;
[Code] .....
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);
[Code] .....
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
is this program correct? for Implementing two Stack in one array. how can i solve it ?
public class Stackation11 {
int max = 10;
int [] array = new int[max];
int top;
int top1;
Stackation11(){
[code]....
Write a method compressDuplicates that accepts a stack of integers as a parameter and that replaces each sequence of duplicates with a pair of values: a count of the number of duplicates, followed by the actual duplicated number. For example, suppose a variable called s stores the following sequence of values:
bottom [2, 2, 2, 2, 2, -5, -5, 3, 3, 3, 3, 4, 4, 1, 0, 17, 17] top
If we make the call of compressDuplicates(s);, after the call s should store the following values:
bottom [5, 2, 2, -5, 4, 3, 2, 4, 1, 1, 1, 0, 2, 17] top
This new stack indicates that the original had 5 occurrences of 2 at the bottom of the stack followed by 2 occurrences of -5 followed by 4 occurrences of 3, and so on. This process works best when there are many duplicates in a row. For example, if the stack instead had stored:
bottom [10, 20, 10, 20, 20, 10] top
Then the resulting stack after the call ends up being longer than the original:
bottom [1, 10, 1, 20, 1, 10, 2, 20, 1, 10] top
If the stack is empty, your method should not change it. You may use one queue as auxiliary storage to solve this problem. You may not use any other auxiliary data structures to solve this problem, although you can have as many simple variables as you like. You may not use recursion to solve this problem. For full credit your code must run in O(n) time where n is the number of elements of the original stack.
I wrote a code but still having a problem with it , am I allowed to use 3 while loops ?
public void compressDuplicates(Stack<Integer> s ){
Stack<Integer> backup= new Stack<Integer>();
int count = 1;
while(!s.isEmpty()){
int temp = s.pop();
[Code] .....
// example 1
Expected output : bottom [5, 2, 2, -5, 4, 3, 2, 4, 1, 1, 1, 0, 2, 17] top
My output: //bottom [17, 2, 2, 2, 2, 2, -5, -5, 3, 3, 3, 3, 4, 4, 1, 0, 17, 17] top
For my classes I wrote I have puts strings into a stack and also a queue and am wondering how to take the top of the stack and the front of the queue and turn those into strings in my main class and run them through while loops that will detect if they are palindromes or not. Right now I am trying to peek and use first to put in my while loop but they don't work with the .charAt because they are not considered strings I think.
import java.util.Stack;
public class Palindrome {
public static void main(String[] args) {
// TODO Auto-generated method stub
String enteredLine;
int leftStack, rightStack;
int leftQueue, rightQueue;
[Code] .....
In my application a series of inputs and a calculated result. At the end of each loop these inputs and calculations are displayed. After the loop is over with the user does not enter a string that is "y" or "Y", I want these inputs and the calculation to be displayed in a First in First Out format or a stack. I am using a LinkedList that is used in a class creating a stack.
Here is the code for my stack.
Java Code:
import java.util.LinkedList;
public class GenericStack<E> {
LinkedList<E> stack = new LinkedList<>();
public void Push(E element) {
stack.addFirst(element);
[Code] ....
Here is the code containing the main method. The methods other than the main method are probably not relevant to the problem, but take a look if you like.
Java Code:
import java.util.*;
import java.text.*;
public class FutureValueApp
{
public static void main(String[] args) {
GenericStack<String> stack = new GenericStack<>();
[Code] ....
The stack seems to be adding the same inputs and the same calculation from the first loop, even when it is on it's 2nd or third loop. I am getting this output.
Java Code:
Monthly Inv.Int. RateYearsFuture Value
$5.002.0%5$315.76
$5.002.0%5$315.76 mh_sh_highlight_all('java');
I tried to write a program to implement a stack but it has a bug I am unable to solve.The bug is that whenever I choose an operation to perform, eg push, After performing the operation, the loop is executed once again and Invalid choice message appears, i.e. the default case. And then the loop again executes to choose further option. Here is my code
class Stack {
private char[] stck;
private int len;
private int top;
[code]....
I am getting a stack overflow error for my method that recursively gets the height of an AVL tree. The odd thing is that it returns the height of the tree the first time I call that method, but when I call it again later on, I get that error, which I does not make any sense to me. I have a base case, where it is supposed to stop when the node is null, but it never reaches that. Also, when I print out the values, it alternates b/w three values: 5, 4, and 24. Something else, which I think is important to state, is that if I put the print statement before my base case, the IF, I get a warning stating that my entire IF statement is dead code...but why?
is that everytime I insert/delete a value into the AVL tree I must make sure that it is height balanced (none of the siblings may have a difference in height from each other > 1); if its not height then I rotate certain nodes accordingly. The first 10 items that I input are: 100, 50, 24, 200, 190, 10, 5, 190, 100 and 4. The pre and in order prints of these, from the console are:
PRE ORDER: 100 10 5 4 24 50 200 190 100 190
IN ORDER: 4 5 10 24 50 100 100 190 190 200 .
private int rheight(AVLNode<E> node) {
//if i put the print statement here, my IF becomes "dead code"
if(node == null){
return 0;
}
else{
[code]....
I am working on implementing a stack using a linked list. Programming the stack operations (push, pop, isEmpty, etc.) was easy but my directions were to provide the user with a menu to choose the operation that he/she wishes to perform. I am new to JFrames/Menus so how to make the stack operations available in a menu.
View Replies View RelatedI was cannot do the action with + - * /.so i cannot have an output.where is the problem ?
Java Code:
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.util.*;
import java.util.Stack;
[code]....
I'm trying to create a class that takes an String from a Stack and checking if it's a palindrome than taking a another String from a queue and checking if that is also a palindrome.
import java.util.Stack;
public class Palindrome {
public static void main(String[] args) {
// TODO Auto-generated method stub
String enteredLine;
int leftStack, rightStack;
int leftQueue, rightQueue;
PalinedromeArray stack1 = new PalinedromeArray();
[code]....
Right now I have three stacks. Each stack holds characters, with the normal operations of pushing and popping. I am trying to compare two characters from stack1 and stack2(each character is a digit character). I would like to be able to do arithmetic on the digit characters and the push the answer on to a result stack.
Ex.) I pop character '3' from stack1 and '5' from stack2. Then I add the two. equaling '8' and pushing that character on to the result stack. This will hopefully in turn allow me to add arbitrary large numbers that integers will not support.
I am having trouble because I believe I am getting some ascii character values when I pop off the result stack. here is a small piece of my code
public void addition() {
char temp1 ,temp2;
int i = s1.getSize();
for(int j= 0;j<i;j++) {
temp1 = s1.pop();
temp2 = s2.pop();
if(temp1+temp2>=10)
[Code] .....
I have a Char stack: ArrayStack<Character> stek=new ArrayStack<>();
The stack is filled with numbers and characters (only '+' and '*' ), but I need to make calculations, so I need the INT values of the numbers i pop from the stack. So each time I need to make a calculation, I have to pop two numbers, convert them into INT ,then add/multiply them, and put them back into the stack again, but as CHAR (because the stack is not accepting them to be added as INT)
int a= Character.getNumericValue(stek.pop()); //stack no1
int b= Character.getNumericValue(rezultat.pop()); //stack no2
int tmp=a*b;
char tmp2 = (char) tmp;
stek.push(tmp2);
I have to implement all the stack methods in java such as push, pop empty, not using the ready methods but have to create them and to execute an exercise but is sth wrong with it
public class Stiva {
/** the problem is here how to declare the stack 1 and stack 2 and kreu(head) gjmax(size)*/
int Gjmax;
int array[] = new int[Gjmax];
int kreu;
private Stiva stiva1;
private Stiva stiva2;
[Code] .....
I have the following code where I call panel repaint method from the action listener of the calc button but it causes stack over flow but when I modify it to call paint component method and removing the super term, the program executes. here is the code
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.Box;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.BoxLayout;
[Code] .....
Im trying to create a linked stack that will hold the starting directory to the current directory, so that when i finish a directory it would go back to the parent. as i go through the files in a directory and find a child directory, i have to stack current directory and process the child directory, when thats done, pop the parent from the stack and continue processing it. Here is my code:
//import io File and ioexception
import java.io.File;
import java.io.IOException;
/*create class that will take a path to a directory, print the name of the argument directory, print the name of each file and directory in argument directory. Prints the directory name and each file and directory inside*/
public class dirStackPrint
[Code] .....
when I run the program, nothing prints, why is that? I'm having trouble understanding the processing of the top, push and pop functions, i have them in my code but they don't seem to be working as they should?