eg: "Sourdough".toUpperCase();
I guess this is actually a 2-part question:
- How does this work? (nothing seems to be passed through the parameter, so how is it that the value or variable is manipulated in this fashion?)
- How would I create a method that does something similar? (ie. adjusting a variable without having it passed through the parameters)
If I have a method that takes an ArrayList of a class called Piece and it uses the setPosition() method from Piece. It is changing the value of the array that I passed in, but I want the ArrayList to stay the same outside of the method. Is there any way I can change only the values on the inside of the method, but keep the same position values outside the method?Here is an example.
Piece class
Java Code: public class Piece {
private int xCoor;
private int yCoor;
[code]....
I tried to Google, but was not able to find anything relevant.
I have a sql query where in I am using preparedStatement which goes something like :
select * from test where parameters in ( ?,?,?,?,?,?,?,?,?,?,?,?,?);
Is there a limit on how many "?" characters i.e. parameters can be there in this query?
I have a webform on JSP page which has several parameters(strings and integers) values and a file to be uploaded to the server through a servlet. It is strange to see that i'm able to upload the file on to the server but not able to get the rest of the parameters in the servlet using request.getParameter("someString") .
<form method="POST" enctype="multipart/form-data" action="/cassino/uploadFile" >
<fieldset>
<div class="form-group">
<label >*ID riparazione</label>
<input type="text" name="idRiparazione" />
[Code] ....
How are methods invoked on the `bird` parameter?
next.xhtml:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml"
xmlns:ui="http://java.sun.com/jsf/facelets"
xmlns:h="http://java.sun.com/jsf/html"
xmlns:f="http://java.sun.com/jsf/core">
[Code] ....
`MyQueueBean` is intended to give out a bird once only, to exactly one end-user. Because it's application scoped, and not session scoped, getting attributes directly from the bean would give inconsistent results.
The birds application is from Facelets Essentials Guide to JavaServer Faces View Definition Framework: [URL] ....
how is the variable passed to the file? Once it's passed, how is it referenced?
I thought static methods could never use instance variables, because they wouldn't know which instance to look at.
From Head First Java, p. 284: "A static method is not associated with a particular instance - only the class - so it cannot access any instance variable values of its class. It wouldn't know which instance's values to use."
Now I was answering some mock exam questions from Cameron McKenzie's SCJA book, and I don't understand one of the options. On page 205, the last question has an option that says: "Instance variables ... are not visible in static methods, unless passed in as arguments." This option is supposed to be correct. Now... how does that work?
Is there a way to have global variable in Java associated to a process ?
I'm coming from PL/SQL world, I'm looking for something like package variables.
I am trying to make the variables that will be taken in from a type='text' box in HTML in NetBeans available to the other servlets as well as store and display the latest value passed into these boxes on the servlet page when the submit button is clicked or display null if the box has not yet received a value. However, I do not understand how to do this and do not understand as to why my current output is always null?
i) Is ServletContext().getAttribute("name of my textbox") really the way to pass the attributes to all servlets?
ii) Is ServletContext() passed in the service request?
iii) How to store the latest value passed into the submit box?
Here is my code
index.html
<html>
<head>
<title>Lab One</title>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
</head>
<body>
First Name: <input type="text" name="firstName">
[code]....
I'm working on an assignment where I need to take radius and height from the user to use with the methods in class Cylinder. I have to use radius and height as input parameters in the methods that calculate: Base area, lateral area, total area, and volume. But when I use height and radius as input parameters then it just prints zeros for all calculated values. When I remove (double radius) from the method it works just fine. So my question is how can I get this to work with radius/height as input parameters? Or am I just misunderstanding will they still be input parameters even if I don't have it written as (double radius) in the method?
import java.util.Scanner;
class Cylinder{
double radius = 0.0;
double height = 0.0;
double baseArea;
double lateralArea;
double totalArea;
double volume;
[Code]...
The one problem in my book was to create a constructor for different shirt features, which I did and ran successfully. Out of curiosity, I also added other methods to see if it would run if the parameters were different from the constructor. It keeps giving me a constructor error. So, my question is, am I able to create a class that uses a constructor with parameters and other methods without errors? I'm guessing there's no reason to since it would be wasted space since the constructor could do it but was just curious if it's possible.
Is everything from the constructor down (in the class) and Shirt.oneShirt (in the main) just a waste of time?
Here's my example:
public class Shirt//class name.
{
int collarSize;//data field.
int sleeveLength;//data field.
int pocketNumber;//data field
public final static String MATERIAL = "cotton";//final data field for material.
public Shirt(int collarSize, int sleeveLength, int pocketNumber)//start of constructor.
{
[Code]...
Generic methods are methods that introduce their own type parameters. This is similar to declaring a generic type, but the type parameter's scope is limited to the method where it is declared. Static and non-static generic methods are allowed, as well as generic class constructors.
1. The method is only exclusively to be used for the declared argument parameter? For example given a generic method:public static <String, Integer> boolean method(Pair<K, V> p1) {}I could only invoke the method if Pair argument parameter is <String, Integer>?
2. Or, it will return a <String, Integer> value?
I'm working with Libgdx but I have a basic java question. I'm trying to access the overridden methods from and interface in another class via a call but I'm not sure how. This is what I've got so far :
Java Code:
public interface Controller {
public void show ();
}
public class MainActivity extends AndroidApplication implements Controller {
@Override
public void showAd(boolean show) {
System.out.println("TEST");
[Code] ....
Right now this code returns a null pointer at the call.
I have two classes, MonsterGame (shown below) and Monster. Monster has a public accessor method to get it's private character variable, which represents the first character of the name of the Monster in question.
I'm just a bit confused as to why am I unable to cycle through the array of Monsters I have in the MonsterGame class and call
m.getCharacter(); (pretty much the last line of code)
public class MonsterGame{
private static final char EMPTY_SQUARE = ' ';
private char[][] gameBoard = new char[10][10];
private Monster[] monsters = new Monster[4];
private int maxXBoardSize = gameBoard.length -1;
private int maxYBoardSize = gameBoard[0].length -1;
[Code] ....
I understand that there need to be instances of objects to call methods, but is that not the case here? the Monster objects are have already been created, no? Do I need to create an index for the array? is the for loop not enough?
I can call a child method from a main method. If I have a parent called "Assessment", a child called "Quiz", and another child called "test". Can I instantiate an object like Assessment a = new test(); and call a method in test.
I know the method can be called if I instantiate the test t = new test() but that defeats the purpose of inheritance...
So I'm just a little unclear about this, but how would I call methods from the 'top' of an inheritance chain? I say 'top' because Object is the top... E.g.:
public class AClass {
public void myMethod() { ... }
}
public class BClass extends AClass {
public void myMethod() { ... }
}
public class CClass extends AClass {
public void myMethod() { ... }
}
Assuming that BClass.myMethod() completely overrides AClass.myMethod() (so that there is no call to super.myMethod() in BClass.myMethod()) How can I call AClass.myMethod() from CClass.myMethod()?
Basically I'm trying to code this program but I keep getting error can't be applied to given types. I know it has to do with my method trying to be called by an array, but I'm just kinda lost.
Write a program that prompts the user to input cash amounts and use a method to calculate the average amount for a week given 7 inputs of daily cash intake amounts for a cash register. Use an array to store the values. Recall that average is the sum of the values divided by the number of values. The method should take argument(s) of type double and return average weekly cash amount as a double.
Make sure you test your program using the test data given below and calls the averageCash() method defined above passing in the values. Verify that the input values are greater than or equal to 0. Negative numbers are not allowed. Output the values used and the averageCash value.
import java.util.*;
public class ArrayHandout {
public static void main(String args[]) {
int[] a=new int[6];
Scanner sc=new Scanner(System.in);
[Code] ....
This current one is to calculate a planes holding pattern. I have to write a method to prompt user to enter speed in knots, then it converts it to km/hr. Another method to calc. pattern width using the speed, another method to calc. pattern length, than a main method which would call and print out the speed in knots, speed in km, pattern width and length.My current problem is on the second method. It works in that I can enter the values and it gives me the correct answers, however it's asking me to enter the speed twice, instead of just once. Anything I try just results in errors and won't compile.
import java.util.Scanner ;
//main method
public class TitleRemoved {
public static void main(String[] args) {
double airSpeedKm = airSpeedOts () ;
System.out.println("That speed is " + airSpeedKm + " km/hr.") ;
[code].....
I want my code to not only work, but be organized and easily readable as well, so I want to avoid bad habits.
Say I have two classes, Author and Book, and I have 2 author objects and 10 book objects. I would like to know how to do two things:
1) Make some sort of connection that makes clear that author X wrote books A, B and F.
2) Call a method from a book object that is connected to an author.
Seeing as I don't know which books will be connected to an author, is there some way to call a method of an object bases on a variable object name? Something like call the getFirstPage() method for every book that is linked to author X?
In this project each individual will create a data analysis program that will at a minimum,
1) read data in from a text file,
2) sort data in some way,
3) search the data in some way,
4) perform at least three mathematical manipulations of the data,
5) display results of the data analysis in numeric/textual form, and
6) display graphs of the data. In addition,
7) your program should handle invalid input appropriately and
8) your program should use some "new" feature that you have not been taught explicitly in class.
(Note: this is to give you practice learning new material on your own - a critical skill of today's programmer.) If you do not have a specific plan in mind for your project, below is a specific project that meets all of the qualifications as long as 7) and 8) are addressed in the implementation.
Everything is done except I need to call my methods in my GradeTester.
GradeBook:
/**
*This class creates an array called scores.
*This class determines the length of the array scores and determines the last grade in the array scores.
*This class sorts the array using a bubble sort, and searches the array.
*This class calculates the mean, standard deviation, and the median of the grades in the array scores.
*Once the grades in the array is sorted, the class then calculates the highest and lowest grades in the array.
*/
public class GradeBook {
public final int MAXARRAY_SZ = 20;
double [] scores = new double [MAXARRAY_SZ];
int lastGrade = 0;
double mean = 0;
[Code] ....
I've been using Eclipse and I realized that it compiles stuff into class files for you. So, I created a new project and each class is a separate .java file, with the .class files already there, but I cannot get rid of these errors. Or, say if I wrote them all into one file and then realized it needs to be 3 separate, or that all need to be in the same src file (oops)? Here are the errors:
Exception in thread "main" java.lang.Error: Unresolved compilation problems:
random cannot be resolved or is not a field
guessp1 cannot be resolved to a variable
guessp1 cannot be resolved to a variable
guessp2 cannot be resolved to a variable
guessp2 cannot be resolved to a variable
guessp3 cannot be resolved to a variable
guessp3 cannot be resolved to a variable
guessp1 cannot be resolved to a variable
guessp2 cannot be resolved to a variable
guessp3 cannot be resolved to a variable
[code]....
I'm trying to build a program that will output what will ultimately look like a simple mario level turned on its side. As part of my output I need the user to define what mario looks like. I do this using Scanner and save the input to String mario. When I try to use that variable in another method it gives me troubles.
import java.util.Scanner;
public class Mario2
{
public static void mario() {
//user defines mario
String mario = ">->O";
Scanner keys = new Scanner(System.in);
System.out.println("What does mario look like?");
mario = keys.next();
System.out.println("Mario now looks like: " + mario);
[code]....
I'm running the code below which compiles ok using latest version of Java and on Sublime. The problem when it complies the output screen is blank and I can only see the text by adjusting the size of the box with my mouse - and then it colours in black. Code and screenshot below. Is there something wrong with the paint/graf part of the code?
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class BackArray extends JFrame {
int store[] = {2,6,4,8,34,67,19,99,10,12,89,68,45,37};
int xcoord = 100;
boolean firsttime=true;
[code]....
I have a JScrollPane with a JTextArea. The JTextArea is loaded with 10 lines of data. I have two JCheckBox's. The first check box sets the scroll to 10. sp.getVerticalScrollBar().setValue(10); The second check box reloads (ta.setText(text)) the text and then sets the scroll to 10. Why does the second one not work? I have attached a simple program. It is probably easier for you to compile and run than for me to go into detail explaining further.
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class Tester extends JFrame {
private static final String text = "1
[Code] ......
I'm trying to add an image on an undecorated JFrame and make it translucent by adjusting its opacity. The problem is that my Image also becomes translucent.
Here is my code:
package Loading;
import javax.swing.*;
import java.awt.*;
public class TransparentFrame extends JFrame{
public TransparentFrame(){
createAndShowGUI();
[Code] .....
How can i make my image opaque but the frame behind it completely invisible. Why I'm getting serialize class warning in this code? that is:
"The serializable class TransparentFrame does not declare a static final serialVersionUID field of type long"
package Experimentation;
import javax.swing.*;
import java.awt.event.*;
public class SimpleGUI1B implements ActionListener {
JButton button;
public static void main(String[] args) {
SimpleGUI1B gui = new SimpleGUI1B();
gui.go();
[code]...
This is a program from Head First Java! since main is static it shouldn't be able to call non-static methods because statics do not use any instance variable values but in the above program we're call a non-static method go() how is it possible?
The only problem I am having is I cannot get my string plainText to go through the encode and prepareString methods.
Is there something in my methods that is wrong, or is it the way that I am calling them?
What is happening is if I enter "this is a test" as a plainText I am getting the samething back with no changes.