The instanceof operator does not appear automatically(IntelliSense) when I press Ctrl+space. Instead some if condition involving instanceof is shown. What is special/unspecial about the instanceof operator not to appear in intellisense?
View RepliesI am trying to test the instanceof keyword. To do this, I've made a method with a simple logical test like so:
Java Code:
Vehicle vehicle1 = new Vehicle();
public void Type(){
if (vehicle1 instanceof Vehicle) {
System.out.println("Type = Vehicle");
}
else if (vehicle1 instanceof Car) {
System.out.println("Type = Car");
}
else if (vehicle1 instanceof Truck) {
System.out.println("Type = Truck");
}
}
} mh_sh_highlight_all('java');
I wanted to try implementing it into the class definitions for Vehicle, then extend that to Car and Truck, but I'm not sure how to use this test in a general case.
The only way this method works is if I set the test to specifically accept a specific object as a parameter.
I want to test multiple objects, but I'm not really sure how else to do this without simply copy-pasting the logical test multiple times and changing the respective objects that are used as parameters.
I want to add a "play" and a "stop" button to stop and play a sound file. Sound file works good, but buttons aren't appearing in the window.
public class SpelaLjud extends JPanel implements ActionListener {
JButton bPlay, bStop;
AudioClip ac;
public SpelaLjud() {
bPlay = new JButton ("PLAY");
bStop = new JButton ("STOP");
add(bPlay);
add(bStop);
bPlay.addActionListener(this);
bStop.addActionListener(this);
[code]....
I am following a tutorial to write a 2d game from scratch in java but when I compile and run my code the application (JFrame) doesn't come up on my screen, it just runs for a second and terminates itself for some reason.
package com.thecherno.rain;
import java.awt.Canvas;
import java.awt.Dimension;
import javax.swing.JFrame;
public class Game extends Canvas implements Runnable{
private static final long serialVersionUID = 1L;
[code]....
I need to add 2 JLists inside a JPanel for a crossword. The JPanel is located SOUTH and I'm using BorderLayout in the constructor to locate the JPanel.
The problem is, I can't see the 2 JLists inside the JPanel. For some strange reason the JLists appear in the center where the crosswordPanel is, even though the clues JPanel method is located SOUTH.
package crossword;
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Container;
import java.awt.Dimension;
[code]....
Here is the code:
the window opens, no errors, but the rectangle does not appear
Java Code:
import javax.swing.*;
import java.awt.Graphics;
public class myGame {
public int x = 20;
public int y = 20;
myGame(){
[Code] ....
I am using a text editor
I am a novice to coding and very new to Java. It appears that I am having a similar problem as the user above "Scott Allen". With a few exceptions. My issue is that when I run the command "javac" from the command prompt I am receiving the same error:- "javac is not recognized as an internal or external command, operable program or batch file"
After reading the comments from above I have configured my System Variables "Path" and "JAVA_HOME" to match the following:
JAVA_HOME: C:Program FilesJavajdk1.6.0_21in
Path: %JAVA_HOME%in; [First Variable]
There is no "Path" User variable on my computer, although there is a "TEMP" and "TMP" in the User Environment variables.
Currently I have the following Java related software installed:
- C:Program FilesJavajre6
- C:Program FilesJavajdk1.6.0_21
- C:Program FilesSunJavaDB
- C:Program FilesEclipse-jee-galileo-3.5.2
I have confirmed the "javac.exe" is located within the in directory of Javajdk.1.6.0_21..When I send "Java -version" to the command prompt the following is returned: java version "1.6.0_26"..Immediately I noticed that the version is wrong, but don't know why or what to do. Below is the output from the command "Java" using the command prompt.
Usage: java [-options] class [args...]
(to execute a class)
or java [-options] -jar jarfile [args...]
(to execute a jar file)
where options include:
-client to select the "client" VM
-server to select the "server" VM
-hotspot is a synonym for the "client" VM [deprecated]
The default VM is client.
[code]....
I'm not understanding why the Jtextfield and Jlabel are not appearing on the dialog window.
public class CreateQuote extends JDialog {
private final JPanel contentPane = new JPanel();
private JLabel interestRate;
private JLabel numberofYears;
private JButton tupac;
[Code] .....
For some reason, when I test out my code, my randomly generated numbers don't appear. Here is a sample result:
> What do you want to generate, integer, double, or character?
>integer
>What is the upper limit and lower limit of the integers you want to generate?
>1
>10
>How many integers do you want to generate?
>10
>BUILD SUCCESSFUL (total time: 9 seconds)
Is this because my code is not passing my parameters correctly? I'm not sure how to fix this either.
Here is my code for reference (it's not completed at the moment)
import java.util.Scanner;
public class NewNumberCharacter {
/** Main method
* @param args */
public static void main(String[] args) {
int return_int;
double return_double;
[Code] ....
1. Is this the JVM ?
2. If so, it uses Java version 7. Who uses Java 8 ?
3. If we install Netbeans, does the JVM gets installed automatically?
I'm writing a JavaFX desktop app, and would like to make it automatically run after installation, but I'm not sure where to look to make this happen (or even if it's possible?). I have successfully created a .dmg installer using E(fx)clipse & Ant. Are there options I'm overlooking which I can use in the build.xml? or am I looking in the wrong place entirely?
View Replies View RelatedI just cant seem to understand the order of precedence here.
class Test{
public static void main(String[] args){
int k = 1;
k += (k = 4) * (k + 2);
System.out.println( k );
}
}
From what I have read compound operators have the lowest order of precedence... But the above piece of code makes the assignment k = 1 + (k = 4) * (k + 2) before evaluating the rest of the statement first.
It then evaluates (k = 4) and proceeds with the remained of the statement 1 + 4 * (4 + 6)....
I dont understand why the first k is assigned 1 but the remaining ks 4. Should they not all be 1 or 4 (I would have thought 4, since += has the lost order of precedence so is evaluated last)??
I know instanceof is an operator and println is a method. But what is the difference between the two? How are they different/same?
View Replies View RelatedAfter the executing the code below:-
class Test
{
public static void main(String [] args)
{
String s = new String("new") ;
String d = new String("new") ;
System.out.println((s==d)+ " "+s.equals(d)) ;
System.out.println(s==d + " "+ s.equals(d)) ;
}
}
OUTPUT:- false true
false
Why did the output change in the second print statement?
The array size is fixed improve it to automatically increase the array size by creating a new larger array and copying the contents of the current array into it .I am using a course class and here is the code for the class
public class Course {
private String courseName;
private int numberOfStudents;
private String[] students = new String[100];
public Course(String courseName)
[Code] ....
As you can see I have the array set to size 100, how do i make so it increments each time the user adds a student.
I am trying to get random shapes to generate automatically. I was able to get just three shapes to generate but nothing random. When I added the random code now only the frame shows up and no shapes. I also keep getting an error with frame.setVisible(true). It says identifier expected. Here is what I have so far:
Main program:
import javax.swing.*;
import java.awt.*;
import java.util.Random;
public class ShapeGen {
public static void main(String [] args) {
//Create window and set title
draw panel = new Draw();
[Code] ....
This is the draw program to generate random shapes:
import javax.swing.*;
import java.awt.*;
import java.util.Random;
public class draw extends JPanel {
public draw(Color backColor) {
setBackground(backColor);
[Code] .....
The program shall assign a new employee ID to the employee and display it on the screen.
The employee ID shall be generated by adding 1 to the largest employee ID already in the employee.txt data file.
You can see I've tried variations of identification++ but have not been successful. I've also tried to get the last or the highest identification in the arrayList but have not done that right.
public static void addEmployee() {
String firstName = Validator.getString(
sc, "Enter First Name: ");
String lastName = Validator.getString(
sc, "Enter Last Name: ");
int identification = 0;
[Code] ....
I also can display all of the employees their identifications and their punches but I cannot narrow it down to searching one employee and displaying information for just the one.
-If the selected value is ‘I’, prompt the user to enter the employee’s ID number.
-If ‘I’ is selected the display shall show the employee’s name and ID, list out each day worked in chronological order, the number of hours worked that day and a total number of hours worked in the two week period.
The report shall prompt the user to re-enter an employee ID of it does not exist in the employee file.
private static void displayReports() {
System.out.println("Report");
Scanner sc = new Scanner(System.in);
String action = " ";
while (!action.equalsIgnoreCase("d"))
[Code] ....
I'm working on an assignment that says the following.
" The array size is fixed in Listing 10.6. Improve it to automatically increase the array size by creating a new larger array and copying the contents of the current array to it.Implement the dropStudent method.Add a new method named clear() that removes all students from the course.
Write a test program that creates a course, adds three students, removes one, and displays the students in the course."
10.6 Listing
public class Course {
private String courseName;
private String[] students = new String[100];
private int numberOfStudents;
}
public Course(String courseName) {
this.courseName= courseName;
[Code]...
My Test Code based off of book
public static void main(String[] args) {
Course course1= new Course("Business");
course1.addStudent("Jay");
course1.addStudent("Silent Bob");
course1.addStudent("Dante");
course1.dropStudent("Jay");
[Code]....
My adjusted 10.6
public class Course {
private String courseName;
private String[] students = new String[100];
private int numberOfStudents;
}
public Course(String courseName) {
this.courseName= courseName;
[Code]...
The problem I'm having is, for the first part of the question where I need to automatically increase the array size. I'm really not great at this stuff. I have tried breaking it down, but can't "get it", I guess.
I assume, it'd be a loop that checks to see if the student array is full and if so, do the increaseArray() part, by maybe multiplying the student array and then assigning it. I just don't know how to do it haha.
My *best* attempt at the loop so far has been
if (students == students.length){
int bigArray = 2*students.length;
String increaseArray()= new String[students];
System.arraycopy(students, 0, increaseArray, 0, students.length);
students= increaseArray;
but,yeah... Doesn't seem to be right.
why operator overloading is not supported in Java.
View Replies View RelatedI need a list of all the dates in 2014 in "YYYY-MM-DD" format (because I need to load them into a database), and I do not want to type them all myself. So is there a way to actually get it generated automatically?
View Replies View RelatedI am new to Java and I am trying to use values that are set for cases in the switch operator.
The first menu ask for you to pick a product and each product has a price on it.
The second menu ask you to pick a state with each state having a decimal value on it.
The third is asking you to put the number of cases and each case is 12 items.
A key note to remember is that each part that a person is choosing is on a different instance!
Here is an example of what i am trying to do.
Menu 1: I picked case 1 that is Computer and it is worth 1000
Menu 2: I picked case 1 that is CT and it's tax is 7.5
Third choice: I picked case 1 and that has 12 items
I want the subtotal witch is: (1000 * 12)
Subtotal in this situation is: 120000
Next i need the total value which is based on what state they picked for the tax percent value picked from the state menu case: (12000 * 0.075 + 120000)
Total value is: 129000
I will post the code I have but based on the choices a person makes will determine the values and I need those values set in the cases to put in a math equation. The problem I am having is retrieving these numbers form the cases inside the menu options and they are on a different instance. So How can I do this in Java code?
Here is the code:
This is menu 1
Java Code:
import java.util.*; //scanners and more
class menu{
public void display_menu() {
System.out.println ("Please select your product"); //Gives user direction
System.out.println ( "1)
[Code] .....
It looks like an upside down v , i cant find it on my keyboard. I assume its a keyboard combo.
View Replies View RelatedThis program is supposed to ask for the operator (+ or -) then ask you for two numbers and do the math. When I run it it comes up- Enter operator. When I say add or sub nothing happens. Here it is:
import java.util.Scanner;
public class Echo1{
public static void main(String args[]){
Scanner userInput = new Scanner(System.in);
System.out.println("Enter Operator");
String operator = userInput.next();
[Code] ....
So I am learning HashMaps/Arraylists and I can't really understand the diamond operator or what it's for. Take the following code for example: Why could we not just do this without the diamond?
Java Code:
import java.util.HashMap;
class Untitled {
public static void main(String[] args) {
HashMap<String, String> map = new HashMap<String, String>();
map.put("California","Sacramento");
map.put("Oregon","Salem");
map.put("Washington","Olympia");
System.out.println(map);
}
} mh_sh_highlight_all('java');
I would like to know that i am getting an error with the random. it is say bad operand types for binary operator ' +'
[/ Random generator = new Random(15) + 1];
I am trying to understand what ivor is saying about the and, and or operators and the mask. If I understand it correctly the & operator prevents you from changing a bit that is one when a mask is involved and changes all others to 0 and the | operator forces a bit to 1 when the mask is 1.
My question is when would i need to actually use the & ,| operators ?when will i need to manipulate the bits in a variable?