Let's say within a class I create a method that takes care of creating a java swing layout with labels, buttons etc.. then attach an action listener (inner class) for each button to change a respective label text. All I would need is that the action listener method can access and modify the label as needed.
Have read about static, protected, private, getters and setters but honestly bit confused about which structure should be adopted as a best practice. Global static protected variables for the labels along with private inner classes implementing ActionListeners believe will do the trick and will be able to access the labels but not convinced this is good practice.
I'm trying to implement a functionality which will control the visibility of three outputText. I'm using a selectOneMenu, which has three options. Each option will enable visibility of one outputText, and rest will be invisible.
Initially all outputText s is invisible as rendered value is false, but when I select different options, their respective outputText s are not visible.
I'm trying to create a program that has two labels... one in the top left and one in the top right... so far when i run it only the one in the top right (label2) shows... also In the program there will be multiple button and when I click a button it will show a different panel and then i can go back to the first panel to select other panels... so far i haven't figured out how to make panels visibility go false/true with actionlistener. last thing... when i have more then one panel added to the frame none of them show up.
Java Code:
//Matthew import java.awt.*; import java.awt.event.*; import javax.swing.*; public class Test{ public static void main(String[] args){
I have two classes involved in this portion. CheckIn_Search
(class #1) is my main UI and I am collecting search information from the user in a jPanel form. When they click "Search" it passes the search criteria to a method that contacts a web service and gets the results. These results are passed to coSearchResults
(class #2) that opens a jFrame and jTable (in modal format, over the main window created by CheckIn_Search.
The user selects a row in the table and that selection data is passed back to coSearchResults to populate a new jPanel form. When the data is passed from coSearchResults, I want to close its window, hide the first jPanel in CheckIn_Search and make the second jPanel visible. To accomplish this, I created a method in CheckIn_Search that simply hides/shows the panels (it will do more later).
I instantiate and call the method in CoSearchResults as part of the button click event. The problem is, it doesn't work. The panels are unaffected and there are no errors. I've put in break-points and it goes into the method.. Here is the coSearch_Results code.
Here is am retrieving the jtable row id and using the first value in the row to get the data from the table model as there is more data than what is displayed in the table. I'm sending that whole row of data to the method that changes visibility.
private void btnOKActionPerformed(java.awt.event.ActionEvent evt) {//GEN-FIRST:event_btnOKActionPerformed // TODO add your handling code here: int rowNum = jTable1.getSelectedRow(); String coNum = jTable1.getValueAt(rowNum,0).toString(); String[] text;
Netbeans tells me it's an illegal start of expression during the initialisation of the interactWithUser method. public class InvertLetter {
/** * @param args the command line arguments */ public static void main(String[] args) { /** * String mit den Kleinbuchstaben. */ final String lowercase = "abcdefghijklmnopqrstuvwxyz";
import java.util.HashSet; import java.util.ArrayList; public class Graph { double [] [] adj; graph (double [] [] a) { adj= new double [a.length][a.length]; for (int i=0;i<a.length;i++) for (int j=0;j<a.length;j++) adj[i][j]=a[i][j]; }
C:UserscDesktopGraph.java:: error: invalid method declaration; return type required graph (double [] [] a)
I'm new to Java and have been stuck on how to use a final declaration statement once it's made. Below is a class I'm creating with the intention of calling it under a main method. I don't understand if I'm supposed to do anything else, like do some sort of get/set, or if the final static line is all I need. And, I don't know how I call it to the main method once I do.
public class Shirt//class name. { int collarSize;//data field. int sleeveLength;//data field. public final static String MATERIAL = "cotton";//final data field for material.
I am not able to understand what does this URI exists at all ?? I feel it making things complex and meaningless or else i am missing something hidden and secret.
Whilst pre-preparing for java certification, one of the online mock exams has slightly confused me by saying my answer was incorrect for multi-dimension array 'declaration and instantiation'.
This is one of the answers i chose - which was marked as incorrect
a) int[][] array2d = {{123}, {4,5}};
Which looks absolutely fine to me.One of the other answers, which i agree is correct and so does the mock exam is
when a new object is created in Java it follows the idiom:
Object obj = new Object(); where the Object() constructor matches the object type Object.
But what if it doesn't? I understand from the Oracle Docs on creating objects and polymorphism that the constructor must be in that object's class or one of its subclasses. However, suppose we wanted to declare a new stack. My first instinct would be:
Stack s1 = new Stack(); But I assume it's valid to do it this way, too:
Object s2 = new Stack(); // Is there a difference here? What are we really saying about s2? I'm guessing s2 is simply an empty stack, but only has access to the Object class methods? I'm not sure why someone would ever do this, but I want to solidify my understanding of the Java hierarchy. Are there really any circumstances where someone would use a subclass's constructor when creating a new object?
I have one interface with three(more than one) method declaration. In the subclass that implements it I want to define only one method not all three not even blank definition of them.Is there any keyword or method for that. How to do it? Is it possible to do it? In GUI we use adapter classes to achieve it. What for console application?
What is exact difference between them? Another thing is when I check (a==b) it retuns me false, but when I check a.equals(b) it returns me with true. Why So?
I have an application that uses an object that is declared globally for the class. Within a method that is triggered by a user event, it creates a new object and assigns it to this global object declaration. My question is, when the object is overwritten multiple times by the user selecting the button that calls this method, will the older instances be garbage collected or is there still a reference to them? Is there any downfall to this logic and if so what would be a solution.
I have to implement all the stack methods in java such as push, pop empty, not using the ready methods but have to create them and to execute an exercise but is sth wrong with it
public class Stiva {
/** the problem is here how to declare the stack 1 and stack 2 and kreu(head) gjmax(size)*/
int Gjmax; int array[] = new int[Gjmax]; int kreu; private Stiva stiva1; private Stiva stiva2;
import java.util.Scanner; public class days { public EnumTest () { this.day = weeks/months/years} final int daysInMonth = 30; //constants final int monthsInYear = 12; final int daysInWeek = 7; public void convert()
[Code] ....
after compiling it shows invalid method declaration ; return type required.
New to java/programming and i cant understand why the pen variable does not display the the correct value ... For example for input 1 ; 2 ; 3 ; 4 both variables will display 10 and i dont understand why pen does not have the value 6 .
import acm.program.*; public class Chap4_ex12 extends ConsoleProgram { public void run () { int pen = 0; int r = 1; int sum = 0; while (r !=SANTINEL) { r = readInt(" ? "); pen=sum ;
Variables defined in interface are public static and final so I was thinking that we should not be able to override the variables in a class thats implementing the interface. But when I am compiling the below class, it compiles fine and gives the correct values. but when I did disp.abhi = 35; it gives a compile error (cannot override final variable)
interface display{ int abhi = 10; void displayName();
This is my first time working with C++ and I have put together this program and came up with two errors and I am unsure what it is wanting me to do. The errors I got are:
1>c:usersownerdocumentsvisual studio 2010projectsweek5week5passing_by_value.cpp(30): error C2064: term does not evaluate to a function taking 1 arguments 1>c:usersownerdocumentsvisual studio 2010projectsweek5week5passing_by_value.cpp(38): error C2064: term does not evaluate to a function taking 1 arguments
#include<iostream> using std::cin; using std::cout; using std::endl; //initialize arrays int incr10(int* numa,int* numb);
I am new in this programming language, java. I have a problem after I set my path ";C:Program Files (x86)Javajdk1.7.0_51in". I made a simple program but an error occurred. Here's the screenshot.....
I continuously get an error for lines 34, 36, and 37 saying that the variables may not have been initialized.
import java.util.Scanner; import java.util.Random; public class MathTutor { public static void main(String[] args) { Random r = new Random (); Scanner input = new Scanner (System.in); /*int min=1; int max=10;*/ int num1,num2,operation; int n1= r.nextInt((9+1)+1); int n2= r.nextInt((9+1)+1); operation= r.nextInt(3); int correctAnswer; int userAnswer;
