I have a msg object that contains an ArrayList<Integer> collection. However, in order to send the elements in the array over the udp socket, it needs to be sent as a byte[] array. So why am I using ArrayList<Integer> over byte array in first place? Well when I receive data from socket from embedded c program, I need to get an unsigned representation of the data, and thus I need to store it in integers, since bytes in Java are unsigned and unsigned chars in c that are greater than 127 will yield incorrect values in java. But when I send an ack back over the socket, I need to send the data back as bytes. So I convert the ArrayList<Integer> to a byte array:
Java Code: byte[] data = msg.toByteArray();
DatagramPacket response = new DatagramPacket(data, data.length,
packet.getAddress(), packet.getPort());
public class Gprs {
...
public byte[] toByteArray(){
[Code] ....
The problem is I get an "Cannot cast from Integer to byte" when trying to cast the integer to byte: data[i] = (byte)m_data.get(i);
programming altogether and after almost reaching half way in the 'Head first java' book I decided to try and apply some of what I've learnt so far and write my first 'Object orientated' program. As this is pretty much the first program I've ever written, I decided to write a program to ask for two integers and add them both together and then present them to the user (the goal eventually being a basic fully working command line calculator with +,-,* and /. I'm expecting many compile errors but not the following errors below.
I have three .java files contained within a folder and after trying to figure out how to compile all three files (as they use one another) all at once, I came across this ---> javac *.java
so I typed this in the command line whilst in the directory containing the three files assuming *.java is the best approach and then I receive the following errors:
inputOutput.java:10: error: cannot find symb c.addition() = intIn.nextInteger(); ^ symbol: variable c location: class inputOutput
I'm writing basically my first program for school. I've written small ones, following instructions, but this is the most vague. I'm having issues. I can't figure out what the error means. I'm not done with the code, but I think the ArrayList is throwing me off. I'm trying to gather user input and sum the total. Here's the code:
package graduationplanner; import java.util.ArrayList; import java.util.Scanner; import java.lang.Double; public class GraduationPlanner { public static void main(String[] args) {
I keep getting the error Admit.java:10 cannot find symbol
import java.util.*; public class Admit { public static void main(String[] args) { sayIntro(); Scanner console = new Scanner(System.in); System.out.println("Information for applicant #1:"); getScore(console); getGPA(console);
[Code] ....
The compiler then reads:
Admit.java:10: error: cannot find symbol score1(ACTScore, SATScore, GPAScore); ^ symbol: variable ACTScore location: class Admit Admit.java:10: error: cannot find symbol
This is likely a simple matter, but my error is confusing given the line it flags matches a working project I have. I get the following error on line 6 in the Controller:
cannot find symbol v.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); ...........................................^ (carrot at the J)
My view file:
import java.awt.*; import javax.swing.*; import java.awt.event.*; public class View extends JFrame{ private JLabel lbl; private JButton btn;
This method accepts 1 integer, amount (the amount of money). Output the minimum number of in quarters, dimes, nickels and pennies used to make up the amount. For example, an amount of 32 would require 1 quarter, 1 nickel and 2 pennies.
This is the question^
My codes are:
public static int change (int amount) { int quarters = amount / 25 ; int firstresult = amount % 25 ; return quarters ; int nickel = firstresult / 5 ;
[Code] .....
The codes were working when i used System.out.println instead of return, but our teacher required us to use return (functions).
Netbeans do not detect any syntax errors, but I when I check the build it retuned areas they were a few; It's a simple program name 5 people, gade them then do final calulatoins it's called "grade tool.
heres the code
package gradingapplication; import java.util.Scanner; public class GradingApplication { public static double score(double score){ if(score >= 90){ System.out.println("A");
[code]...
~Problems~
1. It has no gui, I don't know java fx, is java groove used? awt is useful for creating spam bots in robot class, I know it's not very useful but it's so much fun.
class SubB{ public void foo(){ System.out.println(" x"); } } public class X extends SubB { public void foo() throws RuntimeException{ super.foo(); if(true) throw new RuntimeException(); System.out.println(" B"); } public static void main(String [] args){ new X().foo(); } }
Why the foo method of class X is not throwing a compile error because according to the override rule, if the superclass method has not declared exception, the subclass method can't declare a new exception...
I have a code in which I am reading input from System.in and Destination is some where else
Here is my code
File file=new File("D:/output.txt"); OutputStream os=new java.io.FileOutputStream(file); Scanner scanner=new Scanner(System.in); System.out.println("Enter Data to write on File"); String text=scanner.nextLine(); int c=Integer.parseInt(text); int a; while((a=c.read())!=-1) os.write(a); System.out.println("File Written is Successful");
In the line while((a=c.read())!=-1)
a compile time error is shown "cannot invoke read on primitive data type int"
I decided to code this quiz I took in class about asking the user to input a string and the code is suppose to check for upper case letters. If a upper case letter is found, it should increase a count by one. Once the check is done, it should display the number of uppercase letters. For some reason I am getting this weird compile error stating that symbols can't be found...
Java Code:
import java.util.*; import java.lang.*; public class StringCheck{ public static void main(String[] args){ Scanner input = new Scanner(System.in); System.out.println("please enter a string: " ); String s = input.nextLine();
I am using a static method to convert a string to an Integer object. Next using a instance method to convert Integer object to an int.
Compiler is giving me two "cannot find symbol" errors:
One pointing to the dot operator between "Integer.valueOf(s)"
The other pointing to the dot operator between "obj.intValue()"
I have latest JDK installed: jdk-7u51-windows-x64.exe
Looks like JCL installed correctly with rt.jar file located in "lib" directory under "Program Files"
Following is source code:
Java Code:
public class StringToInt { public static void main (String args []) { String s = "125"; Integer obj = Integer.valueOf(s); int i = obj.intValue(); i += 10; System.out.println(i); } } mh_sh_highlight_all('java');
Im trying to loop through a hashmap of objects. They are defined as People objects. People has two subclasses , Instructor and Student. As I am looping through the map of People, I am searching for class Instructor. If I find it, I want to access its method getDepartment in a println by casting to Instructor. When I do I get a runtime error:
Exception in thread "main" java.lang.ClassCastException: java.util.HashMap$Node cannot be cast to uStaff.Instructor at uStaff.PersonApp.menu(PersonApp.java:108) at uStaff.PersonApp.main(PersonApp.java:21)
//Instantiate the different Person, student and instructor objects Person thisPerson = new Person(01,fName,mName,lName,email,ssn,age); Student thisStudent = new Student(02,"Stacey","Marie","Morgan","smorgan@gmail.com","213-45-6789",20); thisStudent.setMajor("music"); Instructor thisInstructor = new Instructor(03,"Joe","Douglass","Wells","joe@drumhaven.com","555-98-3029",46); thisInstructor.setDepartment("Computer Science");
I ve got a 2d array and I want to cast it in an 2d arraylist. I ve create a function that cast an array to arraylist. My problem arises, when I tried to parse the whole 2d matrix to the arraylist. I use the following code:
Java Code: double sums[][] = computeSums(lab, projections); ArrayList<ArrayList<Double>> lists = new ArrayList<ArrayList<Double>>(); ArrayList<Double> nu = new ArrayList<Double>(); System.out.println(sums[0].length); for (int i = 0; i < sums.length; i++) {
The problem is that only the first matrix sums[0] is copied to the 2d arraylist sums.length times. How is is possible to store all the different sums matrices to the arraylist??
I'm actually trying to complete the excersise of the Servlets and JSP book in page 303 but I'm getting the following error in Eclipse Cannot cast from String to ArrayList(JSP).Here is the code
<%@ page language="java" contentType="text/html; charset=ISO-8859-1" pageEncoding="ISO-8859-1"%> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <%@ page import="java.util.*" %> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"> <title>Hobbies Sharing</title> </head>
[code]...
The error as it appears in line <% ArrayList al = (ArrayList)request.getParameter("Names"); %>
When does an internal cast actually happen? I am aware that compound assignment operator do an internal cast. Does it happen in Assignment 1?Assignment 2?Assignment 3?Assignment 4?
Java Code:
public class Parser{ public static void main( String[] args){ byte b=1; short s=1; int i=1; s=b;//Assignment 1 s<<=b;//Assignment 2 b<<=s;//Assignment 3 s +=i;//Assignment 4 } } mh_sh_highlight_all('java');
Exception in thread "AWT-EventQueue-0" java.lang.ClassCastException: java.lang.String cannot be cast to java.lang.Boolean at javax.swing.plaf.synth.SynthTableUI$SynthBooleanTa bleCellRenderer.getTableCellRendererComponent(Synt hTableUI.java:731) at javax.swing.JTable.prepareRenderer(JTable.java:573 1) at javax.swing.plaf.synth.SynthTableUI.paintCell(Synt hTableUI.java:684)
Is there an advantage in using byte instead of int beyond the space savings? In my program, I'll never need close to the max value of a byte, let alone int, so it seems like a waste to make my primitives ints.
