Java Calculator - Numbers Are Not Adding

Jul 12, 2014

So I was making a Java Calculator that only adds. The problem is that the numbers are not adding. I think it is because whatever has been clicked is not being saved to be added.

import java.awt.BorderLayout;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;

[Code] .....

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Java Calculator - Making Numbers To Stay At Textfield

Jul 12, 2014

How can I make the numbers to stay at the textfield of my calculator instead of disappear like when I type 1 then hit the + sign the number 1 disappears from the textfield I would like to have this (1+1) showing in the text field and also if try to press only + , * , - , / to show error.

this is my code

public class Calculator extends javax.swing.JFrame {
private double TEMP;
private double SolveTEMP;
Boolean addBool = false;
Boolean subBool = false;
Boolean divBool = false;
Boolean mulBool = false;
String display = "";

[Code] ....

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Dec 6, 2014

I've made a calculator that can add, subtract, multiply, and divide, but I still need a clear function and a square root one for it. I've tried going on the various calculator tutorials, but they don't work.

And here's my code:

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class Calculator extends JPanel implements ActionListener
{
private JTextField display = new JTextField("0");
private String button = "789/456*123-0.+=";
private double result = 0;

[Code] .....

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Jul 8, 2014

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Feb 14, 2014

I am new to java and during my classes we built a basic calculator. I want to extend my calculator and added function to square numbers.Here is my program:

Java Code:

package calculator02;

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

[code]...

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Nov 16, 2014

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] .....

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Error Adding Two Numbers?

Nov 5, 2014

package calculator;
public class operations {
int a = 5;
int b = 10;
public void add(int a,int b)
{
int c = a+b;
System.out.println(c);
}
}

I am not getting output to this question though it runs.

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Mar 11, 2014

how can I add the numbers in quantity where it will automatically put in total?

im using netbeans.

just want the codes for how to add the listed quantity?

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Adding And Subtracting Positive Or Negative Two Numbers Of Any Length With Strings?

Feb 3, 2014

You are to design a Java application to carry out additions and subtractions for numbers of any length. A number is represented as an object which includes a sign and two strings for the whole and decimal parts of the number. And, the operations must be done by adding or subtracting characters directly. You are not allowed to convert these strings to numbers before the operation.

The program must use a "Number" class which includes at least the following methods:

Number ( );
Number (double n);
Number add (Number RHS);
Number subtract (Number RHS);
String toString ( );

This is what i have but it only adds positive numbers and it doesn't subtract problems like 7.05-8.96. Also some of it was what our teacher gave us like alignwhole method

import java.util.Scanner; 
public class Number{
private String whole;
private String decimal;
private String sign;
  public static void main (String[] args){
 System.out.println("Enter two numbers");

[code]....

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Adding And Subtracting Positive Or Negative Two Numbers Of Any Length With Strings

Feb 5, 2014

You are to design a Java application to carry out additions and subtractions for numbers of any length. A number is represented as an object which includes a sign and two strings for the whole and decimal parts of the number. And, the operations must be done by adding or subtracting characters directly. You are not allowed to convert these strings to numbers before the operation.

The program must use a "Number" class which includes at least the following methods:

Number ( );
Number (double n);
Number add (Number RHS);
Number subtract (Number RHS);
String toString ( );

The below code is what our teacher gave us to start with, but it needs to add and subtract positive or negative numbers of any length. This code only adds positive numbers. Need to write code for subtraction .

Java Code:

import java.util.Scanner;
public class Number{
private String whole;
private String decimal;
private String sign;

[Code] .....

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Mar 8, 2014

I'm just not noticing why it won't display the answer. I'm trying to solve this book problem......

"Write a for loop that calculates the total of the follower series of numbers:

1/30 + 2/29 + 3/28......+30/1"

Here is what I have..

public static void main(String[] args) {
double total = 0;
for (double a = 1, b = 30; b < 1; a++, b--) {
total += (a / b);
}
System.out.println(total);
}
}

When launched, the output is 0.0. I tried changing the variables a and b to doubles but didn't change anything...

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Oct 28, 2014

I can not this to work correctly.

public static void main(String[] args) {
FloatWrapper x1=new FloatWrapper(0);
FloatWrapper x2=new FloatWrapper(0);
do{
switch(menu()){
case 'a': if(dataInput(x1,x2)) add(x1,x2); break;
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[code]....

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Jul 29, 2014

I am trying to make a calculator using Java GUI. I've managed to make an ActionListener and add it to a button, but I've made an error in my code that I'm unsure of how to solve. Because of how I've written the code, only one number can be placed in the text field. For example, the an ActionListener for the three button on the calculator was added to the button, but no matter how many times the user presses the button, only one 3 will appear in the text field. The code is below:

import javax.swing.*;//import the packages needed for gui
import java.awt.*;
import java.awt.event.*;
public class Calculator {
public static void main(String[] args) {
JFrame window = new JFrame("Window");//makes a JFrame
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[code].....

As you can see, because the compiler forces the String variable to be final, so when the user presses the button, the code simply shows how a space character and three character would look like, because the String variable can't change. How do I write my code so that every time the user presses the button, a character is added to the text field?

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import java.util.Scanner;
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[code]....

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import java.util.*;
import java.lang.*; 
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import java.util.Scanner;
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import java.awt.*;
import java.awt.event.*;
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[Code] .....

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I have left actionPerformed practically blank, what to put in ?

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
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* Created by IntelliJ IDEA.
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* Changing Face Program.
*/
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[code]...

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import javax.swing.*;
import java.util.*;
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[Code] ...

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package name;swing library found in javax called to use the graphical contents.

import javax.swing.*;
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[code]....

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[Code] .....

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import java.awt.BorderLayout;
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import java.awt.FlowLayout;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

[Code] ....

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Sample Output :

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Enter Choice: * <enter>

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[Code] .....

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I thought

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