I have a simple doubt
float k = 0;
k+=0.2;
k=k+0.2; // here compilation error
compliation error Type mismatch: cannot convert from double to float
My question is why not a complilation error at k+=0.2;
My GUI class:
import java.awt.FlowLayout;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import javax.swing.JFrame;
import javax.swing.JTextField;
import javax.swing.JPasswordField;
[Code] ....
Eclipse error message:
Exception in thread "main" java.lang.Error: Unresolved compilation problem:
Type mismatch: cannot convert from void to JTextField
at GUI.<init>(GUI.java:58)
at Apples.main(Apples.java:7)
I copied this from a thenewboston tutorial and he uses an old version of java but im pretty sure ive copied character for character!
I'm not getting why my program is giving error.
package rockjava;
import java.text.NumberFormat;
import java.util.Scanner;
public class file4 {
public static void main(String[] args)
[Code] ....
Please Input Num of Pods + Num of Keys= 20.5
Exception in thread "main" java.util.InputMismatchException
at java.util.Scanner.throwFor(Unknown Source)
at java.util.Scanner.next(Unknown Source)
at java.util.Scanner.nextFloat(Unknown Source)
at alijava.file4.main(file4.java:14)
(It is not accepting double values. However working fine for integers.)
Here is a code and error .....
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import java.util.*;
import java.io.*;
public class Numbrosia {
static int [][] board = new int [5][5];
public static void main(String[]args){
Scanner scan = null;
try{
[code]....
What is the difference between float and double?
View Replies View RelatedI've recently came into reading that term big decimal, but I still don't fully understand what the benefit it is or why wouldn't you just use double and say have the program stop after a certain range?
View Replies View RelatedIs there a method in Java API that truncate the float part of a double variable after a given number of digits?
Example: if the number of digits to be truncated is 2, so the method truncate (6.9872) to (6.98) ,
I tried to write a method that do that but it was very difficult.
class Passenger{
String name;
int age;
char gender;
int weight;
public Passenger(){
[Code] ....
This is showing error.....error it gives isthat it cannot change from string type to passenger type......... How to do it??????
Each time i create a new project or try to compile my workflow (run as GenerateDemo.mwe2 file by write clicking on the file the run as --> WME2 Workflow) it prompts the error I've attached the picture of.
What is it for? How can i get rid of it?
I tried running this program but shows some compilation error of cannot find symbol . in following:
p1.num, p2.num and p3.num
cass Guessgames
{
void startgame()
{
Players P1=new Players();
Players P2=new Players();
Players P3=new Players();
boolean p1isright=false;
boolean p2isright=false;
boolean p3isright=false;
int guessp1=0;
[code].....
I have a String repersentaion of some Object.I want that object convert back into some class type how can I do this?
View Replies View RelatedI've a .java file that won't compile, but produces no errors (in cmd prompt).
I think its the import of java.util.ArrayList thats causing the problem (because it can compile a different file in the same source folder) - so i'm assuming its the classpath that is wrong. which is fine. i love fighting with classpaths.
But why isn't it providing me with an error. the compiler usually goes bat-sh.. crazy if the -cp is incorrect!
Its because I'm switching between command prompt and a text editor and it hadn't saved the file for some reason, and still won't am getting rid of this editor!!
I want to know if there is any general rule/pattern about things which give compilation fails and things which go for Runtime error/exception. OR only way is to remember all of them and there is no actual pattern in it.
View Replies View RelatedI'm having some difficulty getting this GUI dice game to compile. I'm using javac and notepad++ for this and I'm getting the following errors:
DiceGame.java:34: error: cannot find symbol
die2label = new JLabel();
^
symbol: variable die2label
location: class DiceGame
[Code] ....
4 errors
My code is as follows:
import java.awt.*;
import java.awt.event.*;
import java.util.*;
import javax.swing.*;
import javax.swing.event.*;
public class DiceGame extends JFrame
[Code] ....
I'm sure the problem is something trivial, but I guess that's all part of the learning process that I have to go through.
We are getting "Code too large" compilation error for one of our class. This class contains public String fields for label ID and value. We use this class for localization, except for English all other language labels come from .properties files.
The reason we are getting this error is because we have a static block in which using reflection we are populating a HashMap with all public fields and their value. The number of fields have gone up to the extinct where we are crossing the 64K limit for a static method. One of the most feasible solution was to use .properties files for English labels as well.
I will be calling this class MyLabels. We defined a super class for MyLabels called MyLabelsExt. And now we are adding labels into the super class instead of the MyLabels. By running some tests we confirmed that the map that we initialize in MyLables class contains all the fields from both MyLabels and MyLabelsExt class.
How is the 64K limit error not coming if the labels are defined in a super class. Does that mean Java is able to identify that some of the fields are coming from parent class, and that is being treated as separate from the child class. And how is the map that we initialize having all the value.
I'm trying to parse and compare the content of a zip file. However I'm stuck at what SHOULD be a very simple problem, however I can't seem to find a solution. I have done the following:
ZipInputStream zin1 = new ZipInputStream(fin);
ZipEntry ze1 = null;
fin2 = new FileInputStream(fileName2);
ZipInputStream zin2 = new ZipInputStream(fin2);
ZipEntry ze2 = null;
//fin.close();
ze1 = zin1.getNextEntry();
ze2 = zin2.getNextEntry();
Which gives me the first entry of each zipfile as a ZipEntry type object. I have tried getting the path of the file (inside the zip file) and using this to create a File type object. This does not seem to work though I get:
Exception in thread "main" java.io.FileNotFoundException: My DocumentsmetadatacoreProperties.xml (The system cannot find the file specified)
at java.io.FileInputStream.open(Native Method)
at java.io.FileInputStream.<init>(Unknown Source)
at java.io.FileReader.<init>(Unknown Source)
And this is because I get a null return from trying to create the File file1 = new File(correctLocation);
I guess I cannot access the file inside a zip file this way. So my question is how can I make a ZipEntry type object into a File type object?
While doing trial and error got caught in the below scenario.
public class Crypt {
public static void main (String args[])
{
/*all I want is calculate a binary number (ex -: 22 , 34) using decimal base (10n).
*So, I have to convert 2 p into 10n form so I have to find n in terms of p . We have x as the input.
* The formula works as below.
*2p =10n
*p ln (2) =n ln (10)
*n = p [ln(2) / ln(10)]
*2 p = 10 p [ln(2) / ln(10)]
[Code] ....
//Students Full Name
firstName = JOptionPane.showInputDialog("Enter student " +
"first name.");
lastName = JOptionPane.showInputDialog("Enter student " +
"last name.");
// Get test grade (numbers)
[b]test1 = JOptionPane.showInputDialog("Enter test1 grade")[/b];
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.
So I have to convert strings to double numbers and there can be no exception.
The strings that aren't numbers or do not fit into a set criteria have to be discarded.
When I try to write this I get an exception when a non-numeric is entered and the code stops.
What can I do? Also, am I finding the average of the array correctly?
import java.util.*;
public class Grades{
public static void main(String args[]){
int arraycount = 0;
final int SIZE = 10;
int validArraycount = 0;
final int ValidArraySize = 10;
[Code] ......
I am writing a code in which a user inputs data as a string and that data must be verified as a valid number. A valid number is anything from 0-100. Then all valid numbers are converted into double numbers.
I am having trouble in how to write the validation part of the code.
Is it suppose to be an if, else statement? And if so how is it suppose to be validated?
I was struggling to use BufferedReader to extract some data and then perform some calculations and then have the results as outputs.
I haven't quite solved that issue but in order to progress, I hard coded some values into my application and proceeded with the actual calculation loops etc.
Currently, the value out put from one of my calculations is given as:
1.1704926E7
How can I make the console show it in a natural way. I've performed the calculation manually and it should be 11704926.5 I don't want to lose that .5!
I am trying to use double data type in a for loop for precise operations and just to see if there could be any problem doing that I tested a small code :
public class doubleLimit {
public static void main(String[] args){
for(double i=-0.1;i<=0;i+=0.01)
System.out.println(i); }}
The output I was expecting is :
-0.1
-0.09
-0.08
-0.07
-0.06
-0.05
-0.04
-0.03
-0.02
-0.01
0.00
But the output of the code is :
-0.1
-0.09000000000000001
-0.08000000000000002
-0.07000000000000002
-0.06000000000000002
-0.05000000000000002
-0.040000000000000015
-0.030000000000000013
-0.02000000000000001
-0.01000000000000001
-1.0408340855860843E-17
Why is the code not working the way I expected, I think it has something to do with any property of double but I am not sure.
I have doubt in generics,
List<int> c=new ArrayList<int>();
why we cannot use primitive data type like int,double.
How to get a double data type in order to display in the view through a servlet:
objReferencias.setImprevistos(request.("imprevistos"));
Question:
request.getDouble("imprevistos));? or
request.getDoubleParameter("imprevistos));?
I've been searching but I have not found the appropriate answer.
Write method distance to calculate the distance between two points (x1, y1) and (x2, y2). All numbers and return values should be of type double. Incorporate this method into an application that enables the user to enter the coordinates of the points.
Hints:
- The distance between two points can be calculated by taking the square root of
( x2 - x1 )2 + ( y2 - y1 )2
- Use Math class methods to compute the distance.
- Your output should appear as follows:
Type the end-of-file indicator to terminate
On UNIX/Linux/Mac OS X type <ctrl> d then press Enter
On Windows type <ctrl> z then press Enter
Or Enter X1: 1
Enter Y1: 1
Enter X2: 4
Enter Y2: 5
Distance is 5.000000
Type the end-of-file indicator to terminate
On UNIX/Linux/Mac OS X type <ctrl> d then press Enter
On Windows type <ctrl> z then press Enter
Or Enter X1: ^Z