String To A Double In Scanner - Performing Calculation?

Apr 23, 2015

This may be a multipart question. Basically I have to write a program that accepts a string, converts it to a double splits it and then performs a calculation.

public static void main(String[] args) {
String input = ""; // initalize the string
boolean isOn = true; // used for the while loop...when false, the program will exit.
String exitCommand = "Exit"; // exit command
String[] token = input.split(("(?<=[-+*/])|(?=[-+*/])"));

[Code] ....

This is the error I get:

Enter a math problemException in thread "main" java.lang.NumberFormatException: empty String
at sun.misc.FloatingDecimal.readJavaFormatString(Floa tingDecimal.java:1842)
at sun.misc.FloatingDecimal.parseDouble(FloatingDecim al.java:110)
at java.lang.Double.parseDouble(Double.java:538)
at Calculator.main(Calculator.java:22)

[Code] .....

How do I go about actually fixing it. Without that line commented out I get this:

Enter a math problem
2+2 <-What I entered
[Ljava.lang.String;@135fbaa4

Also, how would I go about using the submethods to check for valid operands and operators (also part of the problem) I have the actual lists made obviously, but am unsure how to get those to work with the problem.

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I am new Java Programming and I am struggling to pass my Java class. How to perform Java but I am trying. For this particular assignment I supposed to:

* Change all variables' data types to double.
* Change the two prompts to request double values
* Change change the two calls to the nextInt() method to nextDouble().

This is the original assignment:

import java.util.Scanner;
public class ArithmeticDemo
{
public static void main(String[] args)
{
Scanner input= new Scanner(System.in);
int firstNumber;
int secondNumber;
int sum;
int difference;
int average;

[code]....

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import javax.swing.JOptionPane;
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for (int i = 0; i < letters.length; i++) {
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Above is my current code. Basically- There is a string called characters of length 26 (1 char for each letter in alphabet), a double relativeFrequency value which does a calculation and the end result is a number with lots of decimal numbers. The score array has set double values within the array.

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I'm not getting why my program is giving error.

package rockjava;
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public static void main(String[] args)

[Code] ....

Please Input Num of Pods + Num of Keys= 20.5
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at java.util.Scanner.next(Unknown Source)
at java.util.Scanner.nextFloat(Unknown Source)
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I couldn't get this code working:

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[Code] .....

Did i write something wrong or can't Scanner be used with String?

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[Code] ....

Matched expression found by findInLine: 34

ef56

is new line? right?

The java.util.Scanner.nextLine() method advances this scanner past the current line and returns the input that was skipped. This method returns the rest of the current line, excluding any line separator at the end.

then 56 is in new line and it must return ef.What is the problem?

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How does the Scanner goes through the String which is passed to it as a parameter. For example, String input = "222 dddd 222 ddd22" is passed to the method and here's the code:

Java Code:

public static void sum(String anything)
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Scanner input = new Scanner(anything)
while(input.hasNext())
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......
......
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{

So, how does Scanner calculates a passed String? I just want to know the way it calculates/reads.

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package jdbc;
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The line in bold is where that error comes up. I know it something simple but I can't remember. I declared both firstName and lastName as Strings and then the test1 I declared as double. I had a similar error in a previous assignment where I had a integer(age) input and then i had an output statement asking for a name all I needed to do was put keyboard.nextLine(); after my age input and I was fine.

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Oct 26, 2014

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I have tried both:

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and
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Here is my code:

Java Code:

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

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Java Code:

import java.util.*;
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public static void main(String[] args) {
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[Code] ....

*NOTE: right where my code says double newDouble = Double.valueOf(newResponse); is where the error is occurring.

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at sun.misc.FloatingDecimal.readJavaFormatString(Floa tingDecimal.java:1241)
at java.lang.Double.valueOf(Double.java:504)
at program13strings.Program13Strings.main(Program13St rings.java:21)

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