My isEmpty method only returns false. Is something wrong? I printed the empty and not empty for testing purposes.
//determines if there are any items in the queue
public boolean isEmpty() {
if (front == -1 && rear == -1) {
System.out.println("empty");
return true;
} else {
System.out.println("not empty");
return false
}
}
I have doubts in string declaration. As I know we can declare string in two ways:
1. String a=new String("Hello");
2. String b="Hello";
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 am using saveToken(request) and isTokenValid(request) to stop duplicate request. But while checking isTokenValid(request), it always returns false.
View Replies View RelatedI have to write a method called censor that gets an array of strings from the user as an argument and then returns an array of strings that contains all of the original strings in the same order except those with length of 4. For example if cat, dog, moose, lazy, with was entered, then it would return the exact same thing except for the words with and lazy.
Currently, my code so far just prints [Ljava.lang.String;@38cfdf and im stuck.
import java.util.Scanner;
public class censorProgram {
public static void main (String args[]){
Scanner input = new Scanner (System.in);
System.out.println ("How many words would you like to enter?");
int lineOfText = input.nextInt();
[Code] ....
I have to make new string array in the method and return words without four letters in the main method
I am new to Java and would like to ask how to do this question specifically:
Code a Java method that accepts a String array and a String. The method should return true if the string can be found as an element of the array and false otherwise. Test your method by calling it from the main method which supplies its two parameters (no user input required). Use an array initialiser list to initialise the array you pass. Test thoroughly.
I need to create a method that returns a new array containing the componentwise sum of its arguments(if length is the same). For instance, if the input arrays are {0,1, 2} and {2, 2, 3} then the output is {0+2, 1+2, 2+3}, i.e. {2,3,5}.If the input arrays have different numbers of elements, the method should return null.
I came with something like this, however i dont know how to make a copy of an array from two arrays. My code obviously wont compile. package whatever;
import java.util.Arrays;
public class hhhh {
public static void main(String[] args) {
double [] a = {1,2,3};
double [] b = {2,3,4};
[code]...
Write a Java method that returns the largest value of an array of doubles passed to the method as an argument.
Back into java wasn't sure how to do it for doubles did one in the main for integers and then added a method changed from int to double and now i'm lost as go why its not working.
package kickstarter9;
public class Kickstarter9 {
public static void main(String[] args){
double myList;
double[] myList = {6.0, 4.1, 2.4, 6.8, 1.9, 9.4, 2.8, 4.6, 9.3};
// find the largest value in the list
[Code]...
I am doing a homework assignment and I am clueless as to what I did wrong or supposed to do in terms of placement of coding. If someone could dumb down their response and tell me what I did wrong
This is what I supposed to do:
1.) Type the following shell for the class:
public class ParadiseInfo
{
}
2.) Between curly braces of the class, indent a few spaces and create the shell for the main() method:
public static void main(String[] args)
{
}
3.) Between the braces of the main()Method, insert a call to the displayInfo() method:
displayInfo();
4.) Place the displayInfo() method outside of the main() method, just before the closing curly brace for the ParadiseInfo class:
public static void displayInfo()
{
system.out.println ("Paradise Day Spa wants to pamper you.");
system.out.println ("We will make you look good.");
}
This is what I attempted to do: I know it is wrong I am just clueless on where to put the code and why
public class ParadiseInfo
{
displayInfo();
public static void main(String[] args)
{
public static void displayInfo();
}
system.out.println("Paradise Day Spa wants to pamper you.");
system.out.println("We will make you look good.");
}
--- Update ---
I have also tried this:
public class ParadiseInfo
{
displayInfo();
public static void main(String[] args)
{
}
public static void displayInfo();
{
[Code]...
The very last attempt I only ended up with one error which is:
G:ParadiseInfo.java:3: error: invalid method declaration; return type required
displayInfo();
^
1 error
Tool completed with exit code 1
Java is very new to me and I have no clue on what I am doing wrong.
I am trying to use method calls with returns but it keeps on showing errors. The errors say class, interface, or enum expected. I realize this error occurs if there is issue with declaring class - but i can't seem to find the error. I will post the code that shows error.
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.text.*;
public class FuelCost extends JFrame
{
// declarations
Color black = new Color(0, 0, 0);
[Code] ....
The error states:
C:UsersPriti BhattaraiDesktopCCAC JavaFuelCost.java:290: error: ';' expected
public double calculateCostToFillTank()
^
C:UsersPriti BhattaraiDesktopCCAC JavaFuelCost.java:292: error: class, interface, or enum expected
return (averageMilesPerTank / milesPerGallonRating) * currentPricePerGallon;
[Code] ....
12 errors
Tool completed with exit code 1
The getGraphics() method in my constructor is returning a nullPointerException and I can't figure out why. This class is extending a JPanel and I thought calling super() would fix it because it makes sense that the JPanel would initialize its graphics object in the constructor, but that didn't fix it. The line that produces the error is in bold. I've narrowed it down to the getGraphics() method is returning null, so the next line that calls the graphics object is actually the one that produces the error.
int leftMargin = 2, rightMargin = 2, topMargin = 2, bottomMargin = 2;
int lineSpacing = 1;
int currentX = leftMargin, currentY = topMargin;
Font defaultFont, customFont;
public HTMLFrame(){
super();
[Code] ....
print(String) is a method I made that draws lines of text on the graphics object, similar to System.out.println(String) in the command prompt.
I'm taking a class in object oriented programming and we have a task to write a method that returns positive, negative or zero depending on the sum of two variables.
I've had a go at it and i've got to a certain point but i'm struggling to get past this on error - return outside method.
public class Test {
public int sumArgs;
public int arg1;
public int arg2;
[Code] ....
The error occurs on the line 'return "Positive";
I am trying to write out a program that takes numerical input from the user and converts it to a date using the English month name. I am experimenting with the method of a "switch" statement without using the "break" clause. However, I seem to be missing something, as Eclipse is telling me I have a syntax error with my block. My curly braces seem properly placed. Also, I made sure to follow guidelines to make my code fit on the screen and remain easy to read.
import acm.program.*;
public class MethodsThatReturnNonNumericValues extends ConsoleProgram {
public void run() {
int month=readInt("Enter month number");
int day=readInt("Enter day");
int year=readInt("Enter year");
[Code] ....
This is what I have to create : Write a method that returns the largest object in an array of objects. The method signature is:
public static Object max(java.lang.Comparable[] a)
All the objects are instances of the java.lang.Comparable interface. The order of the objects in the array is determined using the compareTo method.
Write a test program in the main method that creates an array of ten Strings, an array of ten Integers, and an array of ten java.util.Dates, and finds the largest string (i.e. in the alphabetical order), Integer, and Date in the arrays.
Name your java class Max and your java file Max.java.
I am struggling a bit with this code as I am sure you can see, and am at loss. I have never used the compareTo method. Am I doing this right, or on the right track with my code?
public class Max implements Comparable {
public static Object max(java.lang.Comparable[] a) {
java.lang.Comparable tempObj = null;
for (int i = 0; i < a.length; i++) {
if (a[i].compareTo(tempObj) > 0)
[Code] ....
I must write a method that accepts a string and returns an int. The method should sum the unicode values of each character, so the string "ABC" should return 198. Also the only string class methods I'm aloud to use are length, charAt, and substring. I just don't know how the get the Unicode value.
View Replies View RelatedI am doing an assignment and I am clueless as to what I did wrong or supposed to do in terms of placement of coding.
This is what I supposed to do:
1.) Type the following shell for the class:
public class ParadiseInfo
{
}
2.) Between curly braces of the class, indent a few spaces and create the shell for the main() method:
public static void main(String[] args)
{
}
3.) Between the braces of the main()Method, insert a call to the displayInfo() method:
displayInfo();
4.) Place the displayInfo() method outside of the main() method, just before the closing curly brace for the ParadiseInfo class:
public static void displayInfo()
{
system.out.println ("Paradise Day Spa wants to pamper you.");
system.out.println ("We will make you look good.");
}
This is what I attempted to do:
I know it is wrong I am just clueless on where to put the code and why
public class ParadiseInfo
{
displayInfo();
public static void main(String[] args)
{
public static void displayInfo();
}
system.out.println("Paradise Day Spa wants to pamper you.");
system.out.println("We will make you look good.");
}
--- Update ---
I also tried it this one and ended up with 1 error..
public class ParadiseInfo
{
displayInfo();
public static void main(String[] args)
{
}
public static void displayInfo();
{
system.out.println("Paradise Day Spa wants to pamper you.");
system.out.println("We will make you look good.");
}
}
Write a static method odd() that takes three boolean inputs and returns true if an odd number of inputs are true, and false otherwise.
View Replies View RelatedHere's what I'm trying to do:
Complete the body of the following method. Use a CharQueue to store the input line as it is being read. The parameter is an EasyReader from Appendix B of the text. Use the method in.charInput( ) to read and return the next character of the EasyReader, and use in.isEOLN( ) to determine whether the next input character is the end-of-line.
public static int counter(EasyReader in)
// Precondition: There is a line of input waiting to be read from in.
// Postcondition: A line of input has been read from in, up to but not
// including the newline character. The return value of the method
// is the number of times that the LAST character of the line appeared
// somewhere in this line.
[EXAMPLE Input: ABBXDXXZX - The value returned by counter would be 4 for this input since there are 4 X's in the input line.]
***When I look at this I understand that I'm being asked to finish the method, that I have 1 input, which is an "EasyReader" object called in and that I use a CharQueue object along with the method isEOLN( ) to grab characters from in while looking for an end of line and then sticking the values in the queue and then I can go through the queue and figure out the number of times that last character shows up in the queue. I just am at a loss on the "how".
Suppose that a certain airport has one runway, that each airplane takes LandingTime minutes to land and TakeOffTime minutes to take off, and that on the average, TakeOffTime planes take off and LandingTime planes land each hour.
Assume that the planes arrive at random instants of time. (Delays make the assumption to randomness quite reasonable.) There are 2 types of queues: a queue of airplanes waiting to land and a queue of airplanes waiting go take off. Because it is more expensive to keep a plane airborne than to have one waiting on the ground, we assume that the airplanes in the landing queue have priority over those in the take off queue.
Write a program to simulate this airport's operation. You might assume a simulated clock that advances in one-minute intervals. For each minute, generate two random numbers: If the first in less than LandingTime /60, a "landing arrival" has occurred and is added to the landing queue, and if the second is less than TakeOffTime /60, a "takeoff arrival" has occurred and is added to the takeoff queue. Next, check whether the runway is free. If it is, first check whether the landing queue is nonempty, and if so, allow the first plane to land; otherwise, consider the takeoff queue. Have the program calculate the average queue length and the average time that an airplane spends in a queue. You might also investigate the effect of varying arrival and departure rates to simulate the prime and slack times of day, or what happens if the amount of time to land or takeoff is increased or decreased.
My Queue Interface: [URL] ....
My Queue Implementation: [URL] ....
My Demo (Main Method) Program: [URL] ....
Right now, I'm struggling with the demo program. I wrote some pseudocode in which I tried to match what the instructions were asking:
for(each minute) {
rand1 = generator.nextInt();
rand2 = generator.nextInt();
if(rand1 < LANDING_RATE / 60)
Add to the landing queue
if(rand2 < TAKE_OFF_RATE/60)
[Code] .....
Firstly, exactly how many minutes am I supposed to be doing this for? The assignment gave me a variable called final int ITERATIONS = 1440 , could that have something to do with how long I loop? Secondly, what exactly do I add to the queue if the conditions are true. For example, if rand1 < LANDING_RATE/60, what would I enqueue to the landingQueue? Thirdly, how am I supposed to check if the runway is free? Does that mean check to see whether the takeOffQueue is empty or not? Fourth, would allowing the first plane to land mean removing an item from the landingQueue? Also, what does it mean by "otherwise, consider the takeoff queue". Does that mean if the landingQueue is empty, I should start removing items from the takeOff queue?
The biggest problem is the fact that I have to calculate the average queue length and average time that an airplane spends in a queue.
So I have 3 classes in this project, and When it compiles, I get a null pointer.
import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.util.Scanner;
public class Project2 {
[Code] .....
*Write a program to simulate this airport's operation. You might assume a simulated clock that advances in one-minute intervals. For each minute, generate two random numbers: If the first in less than LandingTime /60, a "landing arrival" has occurred and is added to the landing queue, and if the second is less than TakeOffTime /60, a "takeoff arrival" has occurred and is added to the takeoff queue*.
*Next, check whether the runway is free. If it is, first check whether the landing queue is nonempty, and if so, allow the first plane to land; otherwise, consider the takeoff queue. Have the program calculate the average queue length and the average time that an airplane spends in a queue.*
I have most of the code done as you can see below:
* Queue Interface: Queue.java
* Queue Implementation: ArrayQueue.java
* Demo Program: Airport.java
Right now, I am stuck on the first calculation which is trying to figure out the average size of the landing queue. For some reason, as you can see at the bottom of my demo program, the average always comes out to be 0.0 and I'm not sure what's wrong.
Secondly, how to calculate the average time a plane stays inside a queue for. Write a program to simulate this airport's operation. You might assume a simulated clock that advances in one-minute intervals. For each minute, generate two random numbers: If the first in less than LandingTime /60, a "landing arrival" has occurred and is added to the landing queue, and if the second is less than TakeOffTime /60, a "takeoff arrival" has occurred and is added to the takeoff queue.
Next, check whether the runway is free. If it is, first check whether the landing queue is nonempty, and if so, allow the first plane to land; otherwise, consider the takeoff queue. Have the program calculate the average queue length and the average time that an airplane spends in a queue.
I have most of the code done as you can see below:
* Queue Interface: Queue.java
* Queue Implementation: ArrayQueue.java
* Demo Program: Airport.java
Right now, I am stuck on the first calculation which is trying to figure out the average size of the landing queue. For some reason, as you can see at the bottom of my demo program, the average always comes out to be 0.0 and I'm not sure what's wrong.
Secondly, how to calculate the average time a plane stays inside a queue for.
Write a method that returns a new array by eliminating the duplicate values in the array using the following method header: public static int[] eliminateDuplicates(int[] list). The thing is that I found the working solution that is written below, but how it works. How to eliminateDuplicates method done with flag and flag2.
Here is the code:
Java Code:
import java.util.Scanner;
public class Exercise06_15 {
public static void main(String[] args) {
java.util.Scanner input = new java.util.Scanner(System.in);
int[] numbers = new int[10];
System.out.println("Enter ten numbers: ");
[code]....
i am trying to write a class method which will take in a string and returns a string which is the reversed version of that string. it compiles fine but when i try to run it it states Main method not found in class StringReverse,please define the main method as public static void main(String[]args). I am new to java and cannot figure out
import javax.swing.JOptionPane;
public class StringReverse {
public String reverseString(String str){
JOptionPane.showInputDialog(null,"Please enter word");
char c = str.charAt(str.length()-1);
if(str.length() == 1) return Character.toString(c);
return c + reverseString(str.substring(0,str.length()-1));}}
I am trying to figure out stacks and queues and was trying to get this Palindrome program working so I could then play with it and use the Java visualizer site but for some reason the program isn't working correctly. It always states that the input is a palindrome no matter what the user input is.
The book that I got the code from is a little old so I changed a couple small things that I thought needed updating like adding scanner. I wanna use one with a custom array based stack and queue class rather than the java.util.Stack and Queue interface, just for understanding stacks and queues better hopefully.
import java.util.Scanner;
import javax.imageio.IIOException;
public class PalTest {
public static void main(String[]args) throws IIOException
{
Scanner scan = new Scanner(System.in);
PalindromeTesting x = new PalindromeTesting();
[Code] .....
My goal is to ask them for their name and if they got it right then it says yes while if they wrote it wrong, it would say no.
Java Code: public static void main(String[] args) {
Scanner name = new Scanner(System.in);
System.out.println("What is your name?");
String sname = name.nextLine();
name.close();
System.out.println("Are you sure it's " + sname + "?");
Scanner tfname = new Scanner(System.in);
String stfname = tfname.next();
[code]....
The problem is it is returning -2, and also returning false when it should be true. There is no error it just is not working correctly.
import java.util.Arrays;
import java.util.Scanner;
/**
* This Script will allow you to add e-Mails and than beable to search for them.
*/
public class eMailSeacher
{
public static void main(String[] args)
[Code] ....
1. Enter an Email
2. Find an existing email
3. Exit
1
Enter the users E-Mail:
josh
-1
Insertion successful.
ans so on .....
I have the code and it works very well, but my professor wants us to use Junit testing to test our code. I've never used JUnit before, how it works. Is it possible to have a boolean value (true or false) randomly set?
Here is the code I need to test:
package musicalinstruments;
class MusicalInstrument {
public String name;
public boolean isPlaying;
public boolean isTuned;
public MusicalInstrument(){
isPlaying = false;
isTuned = false;
[Code]...