Swing/AWT/SWT :: Void Is Invalid Type For Variable Action-performed
May 1, 2015
Here is part of my program that contains the code giving me problems.
import java.awt.EventQueue;
import javax.swing.JFrame;
import java.awt.Label;
import java.awt.BorderLayout;
import java.awt.Button;
import java.awt.TextArea;
import java.awt.Choice;
import javax.swing.JRadioButton;
[code]....
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May 1, 2015
I get an error in a program "void is an invalid type for the variable action performed"
Here is the code of my program.
import java.awt.EventQueue;
import javax.swing.JFrame;
import java.awt.Label;
import java.awt.BorderLayout;
import java.awt.Button;
import java.awt.TextArea;
[Code] .....
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Jun 25, 2014
I am new to Java and trying to learn it.I wrote the following program but while creating the method nav i am getting errors.
Error:- void is an invalid type for the variable nav
import org.openqa.selenium.*;
import org.openqa.selenium.firefox.FirefoxDriver;
import java.util.*;
public class YahooHomepage {
private static WebDriver driver;
[Code] .....
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Jun 9, 2014
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!
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Jun 12, 2014
I want to write a method which would give us a rectangle with numbers. The input is an integer which represents the length of a line in rectangle and the result type is void. The example for n=4 is:
3210
0321
1032
2103
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Jun 13, 2014
The id variable is the problem Java Code: package com.cjburkey.games.boxee.objects;
import java.awt.Graphics;
import java.awt.Rectangle;
import com.cjburkey.games.boxee.GameState;
import com.cjburkey.games.boxee.resources.Images;
public class Block extends Rectangle {
[code]...
In the constructor, it returns corrent numbers, in the draw method, it returns 0. Why?
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Sep 25, 2014
I am currently working on modules of a java program but am having issues with this module . it gives this error code"syntax error on token '?', invalid primitive type".
This is my code:
import java.awt.*;
import java.awt.event.*;
import java.io.PrintStream;
import java.rmi.Naming;
import java.util.StringTokenizer;
[Code] .....
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Apr 5, 2015
Getting the following error at line 13.
Multiple markers at this line - void is an invalid type for the variable loadDictionaryFromFile - Syntax error on token ")", ; expected - Syntax error on token "(", ; expected
Line 13 starts public void load....
Code:
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.util.Scanner;
public class PirateTranslator
{
public static void main(String[] args)
[Code] .....
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Dec 31, 2014
I am making an application in java, inside static void main, i want to customize all buttons, text areas and want to put them on desired location inside application. I have tried to use setbounds but can not use it, how can i use it, or is there any other way or layout to make my application components customized layout.
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Feb 22, 2014
I'm using Eclipse with the Window Builder Pro plugin to create a Java program. I noticed that when I had Eclipse create an action listener for a combobox in a Swing GUI it created an AWT listener.
Did I choose the wrong type of listener? I want my code to use the Swing components because I understand that they are more portable.
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Oct 25, 2014
So im making a calculator just basic 4 function with a clear button. as i am working into this project i am running into an issue of assigning which click sets what. For instance i click the two button how do i tell it to assign it to firstNum, versus secondNum?
private class theHandler implements ActionListener{
public void actionPerformed(ActionEvent event){
if(event.getSource()==one){
firstNum=1;
}
if(event.getSource()==two){
secondNum =2;
}
if(event.getSource()==three){
secondNum =3;
}
So this for instance allows me to set one to the firstNum and then add it to two or three but im not sure what to do next. I have in my mind i want to do something like make three listener classes, that operate in sequential order like you pick the first numbers, click an operation, and then select the second numbers then hit the operation(equal) button to display answer. Am i on the right track or what?
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Jul 27, 2014
I am trying to understand Life time of a variable by writing a below program. But unable to compile it as it is throwing some error. Code snippet and error as follows,
// Understanding Lifetime of a variable.
class LifeTime {
public static void main(String args[]) {
int x;
for(x = 0; x <3 ; x++) {
int y = -1; // y is initialized each time block is entered
[Code] .....
Please refer to the print screen attached 'LifeTime.jpeg' to this thread to know more about error.
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Jul 14, 2014
I have three JComboBoxes. When the user selects an entry in the first JComboBox the entries in the second are set. For this I use an Action extends AbstractAction which is bound to the first JComboBox.
I have also bound an Action to the second JComboBox.
Problem: this also fires when the entries on the second JCombox are added which leads to a Nullpointer.
I need a Listener which only reacts to user input, and does not react when the model of the JComboBox is changed.
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Aug 3, 2014
I am relatively new to java. . I cannot...(actually do not know) how to change the actionlistener (actionPerformed) after the second click in an array of JButtons. This is how the program performs right now.
On the 1st click on the grid, the border of the button clicked will change to 'blue' and another button will change its boarder to 'red'. on the next click the same action is performed.
What I need is to change action when the 'red' bordered button is clicked, lets say change the color of the buttons from the 'red' to the 'blue' buttons.(x 3 buttons).
The logic about how to perform the final result I think I can do on my own but my problem is how to change the action when the red bordered button is clicked.
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.BorderFactory;
[Code] .....
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Dec 3, 2014
I've got the layout put correctly but I can't seem to get my action listeners to work correctly.
import java.awt.event.*;
import javax.swing.*;
import java.awt.*;
public class PizzaOrderDriver
{
public static void main(String[] args)
{
JCheckBox show1;
[Code] .....
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Apr 23, 2014
I am new to threads, This is a project about 2048 game to be more accurate, and i want this project to run in this thread that i make in main...
My main:
public class Execute {
public static void main(String[] args){
Display d = new Display();
Shell s = new Shell(d);
Model m = new Game2048Model();
View ui = new Game2048View(m.getBoardArr(),d,s);
[Code] ....
And the error is:
Exception in thread "Thread-0" org.eclipse.swt.SWTException: Invalid thread access
at org.eclipse.swt.SWT.error(Unknown Source)
at org.eclipse.swt.SWT.error(Unknown Source)
at org.eclipse.swt.SWT.error(Unknown Source)
at org.eclipse.swt.widgets.Display.error(Unknown Source)
at org.eclipse.swt.widgets.Display.checkDevice(Unknown Source)
at org.eclipse.swt.widgets.Display.readAndDispatch(Unknown Source)
at view.Game2048View.run(Game2048View.java:55) //problem at Run
at java.lang.Thread.run(Unknown Source)
Here is the problem....
@Override
public void run() {
while(!shell.isDisposed()){
if(!display.readAndDispatch()){
display.sleep();
}
}
display.dispose();
}
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Nov 16, 2014
This is my first servlet program. I wanted to try a web application where "register" user module will be in servlet program.I can access my index.jsp but when I enter values and click submit.
I get "There is no Action mapped for namespace [/] and action name [RegisterUserServlet] associated with context path [/TrainingApplication]. - [unknown location]".
Here's my index.jsp file:
<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
pageEncoding="ISO-8859-1"%>
<%@ taglib prefix="s" uri="/struts-tags"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
"http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
[code]....
I am using apache-tomcat-8.0.14 server.
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Mar 31, 2014
How can I store a value in long type variable whose range is greater than int type variable ....
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Feb 22, 2015
I have buttons created on a frame and then I register the listener from a controller in a controller-view relationship.
When I click the button on the face, the action never executes for some reason. I thought maybe there was a problem registering the listener but I can call the buttons doclick() method and it executes as it should. Perhaps I'm overlooking something really obvious here but I can't see it.
btnEight = new JButton( "8" );
// btnEight.addActionListener( controller );
btnEight.setBounds( 212, 90, 41, 23 );
frame.getContentPane().add( btnEight );
and then I add the listener
public void setController( ActionListener theController ) {
Component[] components = frame.getContentPane().getComponents();
for ( Component component : components ) {
if ( component instanceof JButton ) {
JButton button = ( JButton ) component;
button.addActionListener( theController );
}
}
again, when i click the button nothing happens. but if i add the following code
btnEight.doclick()
the actionPerformed invokes in theController as I intended.
You can see the entire project on GitHub so you can see the full context. The controller class contains the listener and the view class contains the buttons.
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Apr 2, 2014
I'm making a Hangman program for Java, here's my code:
import java.util.Scanner;
public class Hangman {
/**
* @param args the command line arguments
*/
public static void main(String[] args) {
String answerWord = WordList.getWord();
[Code] .....
The Compiler gives me this only error:
Hangman.java:39: error: unexpected type
displayWord.charAt(i)=userInput.charAt(0);
^
required: variable
found: value
I understand that charAt returns i as a value and not a variable. What do I use to return a variable as I intended?
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Oct 10, 2014
I've got an abstract class
public abstract class AbstractClass
{
//stuff
}
And a few classes that inherit from it
public class Class1 extends AbstractClass
{
//stuff
}
public class Class2 extends AbstractClass
{
//stuff
}
within another class I have a private variable with the type of the Abstract class, and within one of the methods I assign an object to the the variable like this:
public class Test
{
private AbstractClass temp;
public testMethod(){
Class1 anObject = new Class1();
temp = anObject;
}
}
Is this legal? Will temp become a Class1 object?
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Feb 19, 2014
how to get an access to the method with a parameter of class type variable, lets say: public void insert(Record newRecord, int pos)?
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Sep 23, 2014
I don't understand how i'm supposed to define a variable when the user has to type it into the program so it can be converted. This program i'm working on is supposed to convert from meters to feet (meter = feet * 0.305) but the user has to type in the meters they want converted. how do i solve the problem that keeps coming up that says "variable meter symbol cant be found" ? I keep trying different lines to no avail
public class Lab2
{
public static void main(String[] args) {
double feet = meter * 0.305;
double meter = feet/0.305;
System.out.println("Enter in feet for conversion to meters");
meter = meter * 0.305;
[Code] .....
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Sep 19, 2014
I would like to avoid "Not on FX application thread" exceptions beforehand. Is there a reliable way to determine if Toolkit.checkFxUserThread is called by a specific method call? Such a check could then be included in the build process.
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Apr 1, 2014
I have created an enumerated data type that represents months. In my program I have asked the user for the month. I hold the month entered by user into a string variable. From that string variable I'm trying to display the month using my enumerated data type. I know I can use if statements, but is there another simple way to do it?
import java.util.Scanner;
public class demo {
//Enum class called month that has constants in it representing months
enum month{january,february,march,april,may,june, july,august,september,
october,november, december};
[Code] ....
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Nov 6, 2014
I don't understand why the object reference variable 'a' cannot be recast from a thisA object reference to a thisB object reference.Is it the case that once a reference variable is linked to a particular object type then it cannot switch object types later on.I am facing the Java Associate Developer exam soon and I am just clearing up some issues in my head around object reference variable assignment,
class thisA {}
class thisB extends thisA { String testString = "test";}
public class CastQuestion2 {
public static void main(String[] args) {
thisA a = new thisA();
thisB b = new thisB();
[code]....
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