Constructors are public by default ,aren't they?
import java.awt.Frame;
import java.awt.SplashScreen;
import javax.swing.JOptionPane;
[Code]....
This code gives me error
The constructor SplashScreen(long) is not visible
I've been creating a digital clock using Java, and have made the mouse cursor invisible after a set period of time (40-seconds) and had the thought to make it visible again if mouse was moved.
Here's the code that makes it invisible:
ActionListener mouseTimeout = new ActionListener() {
public void actionPerformed(ActionEvent e) {
setCursor(blankCursor);
}
};
/* Make mouse cursor disappear after 40 seconds */
Timer mTimeout = new Timer(40000, mouseTimeout);
mTimeout.start();
And here is what I have so far for making it visible again:
MouseMotionListener mouse = new MouseMotionListener() {
@Override
public void mouseDragged(MouseEvent e)
{
}
@Override
public void mouseMoved(MouseEvent e)
{
}
};
I have tried using "setCursor(DEFAULT_CURSOR)" but NetBeans says that it "cannot find symbol" .....
I'm trying to make a button that will make a panel not visible and then will make another panel visible but i keep getting this error...
test.java:19: error: local variable panel is accessed from within inner class; needs to be declared final
panel.setVisible(false);
^
1 error
Java Code:
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class test{
public static void main(String[] args){
JFrame test = new JFrame("Test");
test.setSize(600,400);
[Code] .....
I'm having an issue when I try to define a variable in a JSP scriptlet, and then in a separate scriptlet on the same page attempt to use the variable. It looks like it goes out of scope.
I also cannot reference a variable from a servlet in a JSP expression tag. So I've had to write the entire page basically in one scriptlet.
I'm using Tomcat 6.0.
I need a small example of an object which is visible to two different threads.
Does saying "an object is visible to two threads" mean that it's fields or methods are being used in both the threads? I am not clear about that.
ensureFileIsVisible not working.
JFileChooser fileChooser = new JFileChooser();
fileChooser.setCurrentDirectory(new File(currentDirectory));
File f = new File(currentDirectory);
ArrayList<String> names = new ArrayList<>(Arrays.asList(f.list()));
for (String s : names)
if (s.startsWith(yearofIssueTXT.getText())) {
fileChooser.setSelectedFile(new File(s));
fileChooser.ensureFileIsVisible(fileChooser.getSelectedFile());
break;
}
int result = fileChooser.showOpenDialog(addNewCoinBody);
The file is not visible because it is at almost the end of the files in the directory. I want the filechooser to automatically scroll so that the file is seen in the list.
I' currently wrking on BeatBox application from Head First Java. I made a jpanel the pane of the frame & when i try to add a JMenuBar object to that it is not getting displayed when i run the code. When i add a menuBar directly to the JFrame object it is visible & working fine but not incase when added to JPanel.
package com.java.BeatBoxGUI;
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Font;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
[Code] .....
I'm trying to make a simple table with JTable class by reading the following tutorial but when try to see my JTable my program doesn't show me nothing! What i'm doing wrong?
[Code] .....
import javax.swing.JScrollPane;
import javax.swing.JTable;
public class MyFirstTable {
public static void main( String[] args ) {
String[] columnNames = {"First Name",
"Last Name",
[Code] ......
I found the following inheritance and encapsulation issue . Suppose you have a parent class with a non-static protected attribute.
package package1;
public class Parent{
protected int a = 10; // this is the non-static protected attribute in question
public static void main(String args[]){
// whatever logic
}// end Parent class
}// end main()
Now suppose you have a child class in another package and you have imported in the parent class.
package package2;
import package1.Parent;
public class Child extends Parent{
public static void main(String[] args){
Parent p = new Parent();
Child c = new Child();
System.out.println(p.a); //should print out 10 BUT DOES NOT
System.out.println(c.a); //should print out 10
}// end main()
}// end Child class
My observation is that p.a produces an error even though, to the best of my knowledge, it should not. I believe the statement "System.out.println(p.a);" should print out a 10.
Am I misunderstanding something about inheritance and encapsulation?
I have a TableView and it is scrolled to have some rows visible. Lets call the top visible row T, and the bottom one B.
I now replace the items in the TableView with a whole new list of items (so new data to view), but I want to scroll back to either T or B.
It seems to me that I have to somehow keep track of the topmost visible row, or the bottom-most visible row, but I can't figure out how to do that.
I am building a little application for personal use where I can track my finance. Now, what I would like to get is an always visible JTable "footer" OR horizontal space field attached to the bottom of the window. The idea is that scrolling down/up wouldn't affect it's visibility(like JTable header). Might a picture tell a thousand words: see attachment.
I am wondering, maybe JTable OR TableModel class has a property to solve this problem(I haven't found any)? Or shall I make another ScrollPane/JPanel? Which path of search shall I pursue?
In my code where the Button Action Performed is created, I have done the following to ensure that the visibility of the JTable and JScrollPane have been set to true. But it does not work?
Code below:
private void RunQueryButtonActionPerformed(java.awt.event.ActionEvent evt) {
jScrollPane2.setVisible(true);
table_001.setVisible(true);
try {
PreparedStatement st =conn.prepareStatement(SQLTextEditor.getText());
ResultSet rs = st.executeQuery();
table_001.setModel(DbUtils.resultSetToTableModel(rs));
table_001.setAutoResizeMode(table_001.AUTO_RESIZE_OFF);
[code]....
I have noticed a strange behavior of Combobox element. The number of visible rows is not the same established by setVisibleRowCount() method. It happens when changing the items list dynamically. The following example reproduces it. I think it is Javafx 8 bug. I have tried unsuccessfully to trigger some event indirectly to refresh the combobox drop down.
import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.ComboBox;
import javafx.scene.layout.HBox;
import javafx.stage.Stage;
public class TestComboBox extends Application {
private int count;
[Code] .....
I am building an application that shows tables with large amounts of data containing columns that should display a thumbnail. However, this thumbnail is supposed to be loaded in the background lazily, when a row becomes visible because it is computationally too expensive to to this when the model data is loaded and typically not necessary to retrieve the thumbnail for all data that is in the table.
I have done the exact same thing in the past in a Swing application by doing this:
Whenever the model has changed or the vertical scrollbar has moved:
- Render a placeholder image in the custom cell renderer for this JTable if no image is available in the model object representing the corresponding row
- Compute the visible rows by using getVisibleRect and rowAtPoint methods in JTable
- Start a background thread that retrieves the image for the given rows and sets the resulting BufferedImage in a custom Model Object that was used in the TableModel (if not already there because of an earlier run)
- Fire a corresponding model change event in the EDT whenever an image has been retrieved in the background thread so the row is rendered again
Btw. the field in the model class holding the BufferedImage was a weak reference in this case so the memory can be reclaimed as needed by the application.
What is the best way to achieve this behaviour using a JFX TableView? I have so far failed to find anything in the API to retrieve the visible items/rows. Is there a completely different approach available/required that uses the Cell API? I fail to see it so far.
I have a JPanel that's using a simple GridBagLayout.
JPanel panel = new JPanel();
GridBagLayout qPanelLayout = new GridBagLayout();
qPanelLayout.columnWidths = new int[] { 0 };
qPanelLayout.rowHeights = new int[] { 0 };
qPanelLayout.columnWeights = new double[] { Double.MIN_VALUE };
qPanelLayout.rowWeights = new double[] { 0.0 };
panel.setLayout(qPanelLayout);
componentCount = 0;
Based on user input I am adding sub-panels to the panel. These sub-panels may vary in height. They take up the full width of the Panel.
public void add(Component comp) {
GridBagConstraints gbc = new GridBagConstraints();
gbc.fill = GridBagConstraints.HORIZONTAL;
gbc.insets = new Insets(2,2,2,2);
gbc.gridx = 0;
gbc.gridy = componentCount++;
panel.add(comp, gbc_questionPane1);
}
The odd behaviour I'm seeing is that if the height of the new sub-panel I'm adding is less than the height of the largest sub-panel currently displayed then the main panel does not repaint. If its height is equal or greater then the Panel does repaint, and any sub-panels that were added but not visible before are now painted. What have I missed?
I was practicing my java skills and came across an exercise in which a non parameter constructor calls a two parameter constructor. I tried a few searches online but they all came back unsuccessful. This is the part I am working on:
public PairOfDice(int val1, int val2) {
// Constructor. Creates a pair of dice that
// are initially showing the values val1 and val2.
die1 = val1; // Assign specified values
die2 = val2; // to the instance variables.
}
public PairOfDice() {
// Constructor that calls two parameter constructor
}
I tried calling the two constructor using the line "this(val1, val2)" but I get an error because val1 and val2 are local variables.
Then I tried to use the same signature: "this(int val1, int val2)" but that didn't work either.
We are making a tic tac toe game for my CS120 class and I am having trouble figuring out how to make our X's and O's. Is there a way to make shapes besides making two lines for an X and an oval with a white smaller oval inside to make an O? We have only learned the basics so far in class (i.e. events, inheritance, client-supplier, etc.)
These are our instructions:
Write a controller that controls the game. There is one human player (the X player) and the computer player (the O player). The name of the class must be TicTacToeController. In a sense, the controller is the game since the controller will 1) create a TicTacToeModel 2) create a TicTacToeView and 3) create a TicTacToeButton (you must write this class following the design pattern covered in class lectures), a label, and text field such that when the button is pushed, the player moves into the cell selected by the text field. After every player move, the computer moves into a randomly selected empty cell. When the game is over, a text message must be displayed somewhere on the screen the gives the status of the game. While you are free to change the appearance of the controller, the basic elements must be provided (a view of the game, a button, and a text field to enter the cell). A sample screenshot is displayed below.And this is the code i have thus far:
[import java.awt.*;
import javax.swing.JFrame;
public class TicTacToeView extends Rectangle
public TicTacToeView(int x, int y, int w, int h) {
super(50,60,w,h);
this.setBackground(Color.red);
JFrame win = new JFrame("Tic Tac Toe");
win.setBounds(10,10,w+100, h+100);
win.setLayout(null);
win.setVisible(true);
win.setBackground(Color.gray);
[code]....
I'm wonder about the issue of constructor for arrays. Let say I have a class tablica, and one component int[] tab. If I get it right until now tab is nothing more than empty reference to some unexisting array?
import java.util.Random;
class tablica{
int[] tab;
tablica (){ // i wish it was constructor
[code]....
Then, I'm trying to build the constructor for class tablica. What can be the parameter of such constructor? Is it fields of array? It is simple forf for basic variable
- I liken values defined in constructor with those global defined in class. But how to do it with array component tab.
If I create array object in main method then how can I use this constructor?
public class TestClass {
public TestClass(String k){System.out.println(k);}
public static void main(String[] args) {
try {
hello();
}
catch(Exception e){System.out.println(e);}
[Code] ....
Explain how to catch block act as constructor with parameter?
Java Code:
package ZooZ;
import java.util.Random;
public class Animal {
int playerOne; <------- Remains 0
int playerTwo; <------- Remains 0
Random random = new Random();
[Code] ....
If you look at the code, I set "playerOne" and "playerTwo", to set them as what was passed in from another class..
In the Animal constructor.
in that constructor the value is 2. But when I use it in the "Bash()" method it is 0 in the console.
Why doesnt the playerOne and playerTwo stay the value it is assigned in the constructor.??
"A constructor cannot be abstract, static, final, native, or synchronized."
I understand on why it can't be all of the above, except "final".
Why can't we have a final constructor, i understand constructors are not inherited, hence no chance/case of overriding etc. But why is it not allowed at all ?
So I am working on a school project and I have 2 classes, class FakeGravity contains all the properites and class BouncyBall is my driver class. For some reason when I try writing
FakeGravity gravity = new FakeGravity( );
I get an error. I am attaching an image of the error, and also attaching the program just in case you need more information. Also I was using blueJ to write the program
dcasarrubias, on 27 October 2014 - 02:44 PM, said:
So I am working on a school project and I have 2 classes, class FakeGravity contains all the properites and class BouncyBall is my driver class. For some reason when I try writing
FakeGravity gravity = new FakeGravity( );
I get an error. I am attaching an image of the error, and also attaching the program just in case you need more information.
The LocalStudent class inherits the Student class. The IDE states an error of "no default constructor in Student class".I understand that if a LocalStudent object is created, the default constructor of its superclass (aka Student class) will be called implicitly.there is no LocalStudent object being created, so why is the default constructor of Student being called ?
The default constructor of LocalStudent is also overloaded by the created no-arg constructor containining subjects = null; . So there is no call to the superclass default constructor from the default constructor of LocalStudent.
public class Student {
private char year1;
public Student(String name, char year){
year1 = year;
}
public char getYear(){
return year1;
[code]...
I am trying to create a user defined Exception. I am using a hard-coded value in the constructor of circle class at the time of object creation.But in the constructor this value becomes 0.
import java.lang.Exception;
import javax.swing.*;
class InvalidRadiusException extends Exception{
private double r;
public InvalidRadiusException(double radius){
r = radius;
[Code] ....
Due to this its always generating InvalidRadiusException even if i am supplying a non-zero non-negative value.
I want to add validation to some of the elements in my constructor.
Person(String idIn, String nameIn, ) {
this.id = idIn;
this.name = nameIn;
}
I want to be able to check that the data for the ID is limited to a certain collection of characters formatted in a certain. For example, I may wish to limit it to 5 lowercase letters or numbers, or a combination of both. How could I do this?
Do we have constructor in abstract class? If we have then what is the use of it?
View Replies View Related