Basically I have a class called Book. Its supposed to have a few simple methods that set the title of the book, mark it as returned or borrowed. So specifically my problem lies in the implementation of the method that decides if the book isBorrowed. I was thinking i'd use a simple if/else statement but the way i've been trying hasn't been successful. This is what i've tried so far.
public class Book {
String title;
boolean borrowed;
boolean returned;
boolean isBorrowed;
// Creates a new Book
public Book(String bookTitle) {
I think I'm about 90% complete with this program but I'm stuck on my adding entries method. It gives me a runtime error which says:
Enter the name: Bill Exception in thread "main" java.lang.NullPointerException at Phonebook.addEntry(Phonebook.java:70) at Phonebook.main(Phonebook.java:49)
Here is my code: /* * This program asks the user for input for a name, phone number and notes up * to 200 entries. It stores every contact in a file. Type 'h' for help while * running this program. */ import java.util.Scanner; import java.io.*;
My issue is that when I run my search, it does find a goal. However, when I try and print the route using my print route method, it just gets stuck in a loop of printing the same two nodes. What is wrong with My A* implementation?
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?
The 2 minute drill from page 69 SCJP kathy and bert book, says regarding Interfaces, that - "A legal nonabstract implementing class must not declare any new checked exceptions for an implementation method."
When I try the below given code in eclipse , it does not throw any errors . (Here I have tried to throw NullPointerException from testFunc whereas the interface function throws IllegalStateExc)
package abstracttesting; public class StaticCheck implements check{ public void testFunc() throws NullPointerException{ // TODO Auto-generated method stub } public static void main(String[] args) { // TODO Auto-generated method stub } } interface check{ void testFunc() throws IllegalStateException; }
I'm doing a project in netbeans. I have to make a on-line bank with all the GUI. In the middle i got stuck with the classcastexception..
public class Banca { public static void main(String[] args) throws IOException, ClassNotFoundException { // dati dei clienti Anagrafica c = new Anagrafica();
[code]...
And here's the class of the activities of an account.. I'm not posting my classes Conto( Bankaccount) & Movimento (Activity) because those two already do what they should..
I'm trying to do the following and my code is putting me in a loop and not allowing me to input a valid entry after using an invalid #.I ask the user for input which contains a loop if the user doesnt use the correct information, however the loop doesnt allow the user to input if the entry fails the which statement
import javax.swing.JOptionPane; // Needed for JOptionPane class public class LoanQualifier { public static void main(String[] args) { double salary; // Annual salary double yearsOnJob; // Years at current job String input; // To hold string input
// Get the user's annual salary. input = JOptionPane.showInputDialog("Enter your " +
I have this code running correctly in Eclipse all except that it seems no matter where I declare, highest, lowest, average they always seem to stay at "0". I have a feeling the location of the Initialization is not the error since I have tried moving it to inside differ loops.
Stipulations on writing this code are:
Note: You do not need to use array to save each input score for this lab. A Single loop to read in each grade, compare with the current highest grade, lowest grade, and calculate the running sum at the same time.
import java.util.Scanner;
/*Write a program that prompts the user to enter the total number of students first. *Then ask the user to input each student’s grade and use loop statements to read in each grade. *Check input grade to make sure 0<=grade<=100, if the user input any other number, print out warning message and ask the user to input a new grade. Display the highest score, the lowest score and the average. */
public class LoopStatements { // Main Method public static void main(String[] args) { // Initialize int grade = 0; // grade value
How to use a constructor with parameters where the user inputs the information? I'm doing a problem where I create a Delivery class that accepts arguments for the year, delivery number within the year, distance code (1 for short distance, 2 for long), and weight of package. The constructor is supposed to also determine the eight digit delivery number (combining the year and delivery number, like 20140054 for this year, package #54).
I know I'm not close to being done but I'm struck on the application with the constructor parameters. If I'm asking the user to input the information, does that mean I have to create a no argument constructor so it will compile? Right now it won't compile because it's asking for the parameters but I can't put them.
This is the class:
public class Delivery { int year; int delNum; double weight; int code;
[Code] .....
And the error is:
CreateDelivery.java:22: error: constructor Delivery in class Delivery cannot be applied to given types; Delivery firstDelivery = new Delivery(); ^ required: int,int,int,double found: no arguments reason: actual and formal argument lists differ in length 1 error
I'm writing a temperature converter for class, and I'm done but one piece that I can't wrap my head around.My input scale radiobuttons work fine, but the output scale radiobuttons don't deselect automatically. They're two different button groups and I wrote them identical save for the variable names.
Total IS those numbers. But question[10] will not cooperate with me and it's getting a bit aggravating as I can't find a logical reason for it to be doing that.how to perhaps lock the value of total and sTotal after 10 button clicks from any?
Write a method called isSorted that accepts an array of real numbers as a parameter and returns true if the list is in sorted (nondecreasing) order and false otherwise. For example, if arrays named list1 and list2 store {16.1, 12.3,22.2, 14.4} and {1.5, 4.3, 7.0, 19.5, 25.1, 46.2} respectively, the calls is Sorted(list1) and isSorted(list2)should return false and true respectively. Assume the array has at least one element. A one-element array is considered to be sorted. public class thirfd {
I have spent some time thinking about the program, and realize I need two loops-- 1 that keeps track of bricks in a row and 1 that keeps track of the number of rows as the Pyramid rises in height. The Pyramid is supposed to be centered on the bottom of the screen. Three CONSTANTS have been required:
I tried breaking the scope of things down by trying step-wise refinement. But, I got bogged down. When I tried a method where both loops were included, I got limited success. For some reason, my equation to center along the x axis seems to be doubling the number of bricks. But, the correct number of total rows of bricks was a success. Also, the Pyramid was centered on the bottom of the screen. Another frustrating failure was that the number of bricks would not decrease as the new layers were created. My thought process was instead of using a loop that counts up (i++) I would use a loop that counts down (j--) which I thought would reduce the number of brick in each row as the "y" coordinate was reduced by each count of the BRICK_HEIGHT.
This is the code that "works". Whenever I add the (j--) the results are NOT what I expect.
/* * File: Pyramid.java * Name: * Section Leader: * ------------------ * This file is the starter file for the Pyramid problem. * It includes definitions of the constants that match the sample run in the assignment, * but you should make sure that changing these values causes the generated display to change accordingly. * [code].....
my application (java 6 RedHat 5.3 x64 ) using clean content jar for extracting data from email messages with attachments (doc, xls, ptt ...etc) After update from CleanContent-2009.1.1.jar to CleanContent-2011.1.1.jar (and any newer version) CompilerThreads will stuck in some cases (pretty often) In that case CPU usage is 100% all time, even when all activities on application are finished.
I was able to isolate several messages and every time when I used CleanContent-2009.1.1.jar it works ok but always stuck with CleanContent-2011.1.1.jar or newer versions!
The goal of this code was to create a program using main method java to analysis a piece text which has been entered from a user.
They do this by entering the text into a scanner which is then analysed by the program. The analysis is to produce word frequency, for example " This is a test" produces this results:
This is a test
1 letter words: 1 2 letter words: 1 3 letter words: 0 4 letter words: 2 5 letter words: 0
The bit that I'm stuck on is producing a mean/average, My mind telling to divide
counts.length by str.length
But I'm not the Best at java and I've tried to implement this but all I get are errors.
Code:
import java.util.Scanner; public class While_Loop { public static void main (String[] args) { while(true){
The problem i believe is that I have the max value set to the first value given out, but every time the loop repeats the Max value gets reset to the next value in the file.
Essentially the program is supposed to read a list of credit card transactions and tell the user which transaction is the highest.
Here's the list of the sample file, note that the number of transactions could change that's why i haven't tried simply passing the values to method.
Bicycle 562.90 Groceries 138.43 Hotel 612.00
import java.io.File; import java.io.IOException; import java.util.Scanner; public class CreditCards { public static void main(String[] args) throws IOException { String fileName = "C:/Users/David/Desktop/CreditCard.txt"; File inputFile = new File(fileName);
While analyzing the thread dumps for a performance issue in our java ee web application, I see many thread dumps stuck on a closing brace of a while loop. Here is the code block of a third party library bitronix (version 1.3.3 SNAPSHOT)
public XAResourceHolderState findXAResourceHolderState(XAResource xaResource) throws BitronixSystemException { Iterator it = resources.iterator(); while (it.hasNext()) { XAResourceHolderState xaResourceHolderState = (XAResourceHolderState) it.next(); if (xaResourceHolderState.getXAResource() == xaResource) return xaResourceHolderState; } return null; }
The thread dumps indicate that many threads are stuck in RUNNABLE state on line number 07. What could be the possible reasons on why a thread could get stuck on a closing brace of a while loop? The iterator of the while loop is a custom implementation.
I'm getting an error trying to run a welcome app from a book. I've looked at the FAQs and can't seem to solve the issue. I'm guessing my path and/or classpath are not right. Here's my path environment variable.
I'm fairly good at Java, but somewhat at a loss when the some of the JavaScript below is mentioned. I've attempted to port the below code, but I'm finding it somewhat difficult.
Parts of JavaScript I'm stuck at porting:
1. I'm stuck on the return statement on the 3rd line.
2. Similarly the lines utilizing "charCodeAt", as I keep getting error "Cannot invoke charCodeAt(int) on the primitive type char"
3. Also on the second to last line, I keep getting the error "Cannot invoke padLZ(int) on the primitive type int".
Link to original javascript
Convert between Latitude/Longitude & OS National Grid Reference points
Original JavaScript
Java Code:
OsGridRef.prototype.toString = function(digits) { digits = (typeof digits == 'undefined') ? 10 : digits; e = this.easting, n = this.northing; if (e==NaN || n==NaN) return '??'; // get the 100km-grid indices var e100k = Math.floor(e/100000), n100k = Math.floor(n/100000);
Firstly, my code is just a demo of my multiplayer game (2 or more players can play simultaneously) to demonstrate my problem without any extra things. I have successfully implemented peer-to-peer (P2P) communication in my game. Later, I decided to add support for client-server communication (ie a central server which is also a player) in my game. It should be much easier than P2P. Now here is the problem:
Suppose, I have 1 server and some clients (may be 1 or more clients). They all should give the following output:
Starting... A B C E F ... ... Done!
They all give the above output without using multi-thread. But using multi-threading, it gives the above output only when there're 1 server and 1 client. I'm using 2 threads (1 for sending, 1 for receiving) for each Socket. That means, each client has only 2 threads for communication but the server has (2 * totalClients) threads.
I've attached my full test project. So, here I'm only showing my 2 thread classes.
ReceiveThread class: class ReceiveThread extends Thread { private ObjectInputStream receiveStream; private BlockingQueue<Character> queue = new ArrayBlockingQueue<Character>(Common.totalClients);
[Code] ....
Since I've attached my full test project, I'm not showing the other 3 classes. They are ServerMain, ClientMain and Common. If I've 2 clients to be connected, then I get the following output:
Server: (Runs first)
Starting... A Client 1 (clientID is 1): (Runs after the server)
Starting... A B B Client 2 (clientID is 2): (Runs after Client 1)
Starting... A
They are stuck at there, even no exception. Actually, the server and the clients are stuck at the line try { ch = queue.take(); } if more than 1 client are connected. It seems that all are trying to receive data. But without using the dedicated threads, they all work as expected even for more than 1 client. Why is this behaviour? How to solve it? Note that I have used the same SendThread and ReceiveThread classes by which I have succcessfully implemented P2P communication.
About my attached test project file:
It has 5 small .java files for the classes as stated above. It is currently faulty when using additional threads. You have to change clientID variable for each client (they are described inside). But it works as expected without additional threads. To test it without the additional threads:
Comment " TODO" linesUncomment the single lines just after " TODO" linesComment the additional thread construction lines (4 lines)
Currently, for a workaround, I'm not using the dedicated threads for sending and receiving data only for client-server communication in my multi-player game. But I'm still using these threads for P2P communication. I don't know why it is and how to solve it.This is the attached test project file as described above.
