Passing Object Argument To A Method - Unable To Call Methods On Argument
Feb 7, 2015
I am trying to pass an object of type Product p to my editProduct method, however trying to call p.getName(); doesn't work and throws a NullPointerException. The same kind of thing works for my displayRecord method (in a different class) and I can call .getName() on Product p, also passed as an argument to that method. Below is my editProduct class. The NullPointerExcepion is being thrown at line 61 (i.e., nameField.setText(p.getName());).
I don't know if I explained right, so here's a line thing of how the classes relate:
And as a side note: adding the line p = new Product(); fixes it and successfully runs the class (including the Save and Quit parts) but obviously I want it to specifically refer to the Product I pass to the method.
I'm asking a question because I don't understand how Product p could possibly be null, because the argument is passed through my DisplayRecord class, which also takes a Product p argument and works. In that class, I have declared Product prod = p; and prod is what I am passing to editProduct.
Can we pass array as a cmd line argument as follows ?
>java TestRun file[], number if yes, in the main(), how do we capture this array ? public static void main(String [] args){ String [] files = args1 ; // or will it be String [] files = args1[]; }
So I have an application where the user logs in (using j_security_check). User is taken to a welcome page where user's name is displayed as a link. When clicking that link I would like to take the user to a page where the user is able to update the credentials (password, address, etc). In this way the user only has access to the link related to that specific user's credentials. I am trying the following structure:
public String selectedUser() { userName = FacesContext.getCurrentInstance().getExternalContext().getRequestParameterMap().get(userName); selUser=uServ.findByName(userName); return "UpdateUser";
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The last line of the stack suggests that a null PK value is being picked up by the FacesContext method in the backing bean. I'm confused because the userName string IS the primary key of the user table which is structured like this:
I am trying to create a class to read data from the JOptionPane. I am trying to create a general procedure and then be able to overload it using the rest. Basically I just want to call the procedure readString with options and without options while verifying that the user entered the correct information.
Java Code: public class BankIO { public static final Object[] mainMenu = {"1. Create Account", "2. Delete Account", "3. Update Account", "4. Display Information", "5. Quit"}; public static final String APPLICATION_NAME = "Banking Pro";
I have a mySql table of PROJECTS, which I am displaying as a list in the index.xhtml. The projectid column contains hyperlinks. When they're clicked I would like the specific projectid row selected to be passed as the query argument into another jsf file (ListProjects.xhtml) which displays all the project values referring to the projectid selected in the index.xhtml. The named query is:
@NamedQuery(name = "Projects.findByProjectid", query = "SELECT p FROM Projects p WHERE p.projectid = :projectid") index.xhtml <?xml version='1.0' encoding='UTF-8' ?> <!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"
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I get the following stack trace. How to correctly pass the hyperlink parameters.
org.jboss.weld.exceptions.WeldException: WELD-000049 Unable to invoke public void com.manaar.beans.SelProjectMgtBean.init() on com.manaar.beans.SelProjectMgtBean@681859ae at org.jboss.weld.injection.producer.DefaultLifecycleCallbackInvoker.invokeMethods(DefaultLifecycleCallbackInvoker.java:91)
I'm writing a Java program to get the gpa of a student as a command line argument. Then display the class of the degree according to some criteria. Here is my code. But it says "ArrayIndexOutOfBoundsException :0". How can I fix this?
public class Stgpa { public static void main(String[] args) { double gpa= Double.parseDouble(args[0]); if(gpa>=3.6) System.out.println("Class of the degree is: First Class Hons"); else if(3.6>gpa && gpa>=3.4)
I don't know how to define "abs." Here are the instructions:
The purpose of this exercise is to add to the IntClass class below a method, abs, that takes as its only argument an IntClass object and returns a new IntClass object representing the absolute value of the argument.
Define the desired method as a class method.
Define the desired method as an instance method.
In each case, use the main method to test your code.
There's two boxes of editable code. I'm having trouble with the first one, the one with "abs."
Here is more code:
My code goes here
}
Here's another box of code that they want me to fill out:
public class MainClass { public static void main( String[] args ) {
One interviewer has asked me one question that why main() method has argument "String[] arg".What is reason behind this ??I am unable to explain it because i never think about it ..
But for the method get() of Paths, I get this error in eclipse.The method get(String, String[]) in the type Paths is not applicable for the argument..Yet on the Oracle documentation site, it uses a similar example:
For reference I am programming Java in BlueJ. I am fairly new to the language and I am having trouble with sorting.
I am trying to call / test all of the 5 sorting methods (at the same time) in the main class. To be specific, the sorted list has to technically outputted 5 times.
I figured out how to call / test Quicksort:
Sorting.quickSort(friends, 0, friends.length-1);
But the others are not working correctly. Specifically these:
For reference, this is the output when it is not sorted:
Smith, John 610-555-7384 Barnes, Sarah215-555-3827 Riley, Mark 733-555-2969 Getz, Laura 663-555-3984 Smith, Larry464-555-3489 Phelps, Frank322-555-2284 Grant, Marsha243-555-2837
This is the output when it is sorted:
Barnes, Sarah215-555-3827 Getz, Laura 663-555-3984 Grant, Marsha243-555-2837 Phelps, Frank322-555-2284 Riley, Mark 733-555-2969 Smith, John 610-555-7384 Smith, Larry464-555-3489
This is the class Sorting, which I should note is all correct:
public class Sorting{ /** * Swaps to elements in an array. Used by various sorting algorithms. * * @param data the array in which the elements are swapped * @param index1 the index of the first element to be swapped * @param index2 the index of the second element to be swapped */ private static <T extends Comparable<? super T>> void swap(T[] data, int index1, int index2){ T temp = data[index1]; data[index1] = data[index2];
[Code]...
This is the Main class in which I am supposed to call the sorting methods, SortPhoneList:
public class SortPhoneList{ /** * Creates an array of Contact objects, sorts them, then prints * them. */ public static void main (String[] args){ Contact[] friends = new Contact[7]; friends[0] = new Contact ("John", "Smith", "610-555-7384"); friends[1] = new Contact ("Sarah", "Barnes", "215-555-3827");
SimpleCharacterReader.java:: import java.io.EOFException; import java.util.Random; public class SimpleCharacterReader implements ICharacterReader { private int m_Pos = 0;
[Code] ....
My task is as follows:
1.) Write a class that takes an ICharacterReader interface as an argument and returns a list of word frequencies ordered by word count and then alphabetically.
And also write a main method of a console application that exercises this class using a SimpleCharacterReader, and prints the output to the console.
For example, if the stream returns "It was the best of times, it was the worst of times" then the output will be:
it - 2; of - 2; the - 2; times -2; was - 2; best - 1; worst - 1;
2.) Test the answers in part 1, by writing unit test cases.
How to pass interface as an argument and what is meant by "writing unit test case"?
class Test3 { } class MySub extends Test3 { } class Test4{ public static void main(String args[]) { MySub m = new MySub(); } }
I learned that if a class and its parent class both have no constructors, the compiler is supposed to complain. When I compiled Test4, i got no errors. why did it give no errors?
So I'm trying to make a simple program which takes in an argument (target) and then looks through an ArrayList of strings. If it finds a string that begins with (target) then it will return the index of that string. If it doesn't find a string which begins with (target) then it will return -1 instead.
For some reason, the program is always returning -1, rather than the index of the string within the ArrayList when there is one which matches the search criteria.
Here is the code:
public int getIndex(ArrayList<String> text, String target) { int i = 0; int index = -1; boolean found = false;
I'm having trouble with how to read a text file into my program so the words can be sorted alphabetically. Should I use something like a FileReader?
An example of what I'm trying to do is a .txt file that holds the statement "java is a simple object oriented and distributed and interpreted and robust and secure and dynamic."
The output should organize the words like so: and and and and distributed dynamic interpreted is java object oriented robust secure simple
Here's what I have:
public static void main(String[] args) { if (args.length != 1) { System.out.println("Usage: java AscendingAlphabet"
[Code].....
I can never get it to read the file correctly, it just prints the "usage: java..." statement.
I have learn that every function in java is treated as a normal function including main() except that execution of a program starts here. I tried to overload it.
But I am getting error while doing so via String type array as an argument of main.
class Hello { public static void main() { System.out.println("Hello"); } public static void main(String... s) { System.out.println("main from Hello");
The output from the debug show that permissions values inside of the ResourceImpl contains the values I'd expect (foo,bar), but inside the interceptor, they're missing. Is there a way to get the arguments in ResourceImpl to pass through to the interceptor?
Log output looks like:
15:59:55,223 INFO [stdout] (default task-9) @edu.psu.swe.fortress.poc.interceptor.FortressProtected(permissions=[]) 15:59:55,229 INFO [stdout] (default task-9) @edu.psu.swe.fortress.poc.interceptor.FortressProtected(permissions=[foo, bar])
There is my code so far, on the line JOptionPane.showInputDialog(null, "Give us a word starting with "+text[i]+":", "tut", 2, image, ?, null);, eclipse gave me 2 extra arguments following the icon and I'm not sure what exactly goes into the 2nd to last, the "selectionValues" argument.
After checking the Java docs, it was apparent that the option buttons goes into the selectionValues argument, but is there a way to work past that if I would only like the default (OK, Cancel) buttons on my window? The school haven't taught us the method to create custom buttons and I doubt I would've been set something that was not taught.
I have a enum class which contains some string which i am comparing to a string i get from a user
Java Code:
public enum Compare { a, b, c, d, e, f } class SomeClass { String method(String letter){ Compare word= Compare.valueOf(letter); } } mh_sh_highlight_all('java');
Everything works fine but when I added a new word to it like "g" it throws the IllegalArgumentException ?
I'm trying to make a simple Caesar cipher that takes in a String as the first argument and a integer shift as the second argument. Namely, there appears to be a problem with the loop and how I have declared the array - I want the converted characters to be put into a new array called newCharacterArray, converted back to a String and displayed in the command prompt window.
public class Caesar { public static void main(String inString, int k) { System.out.println("String: " + inString); char inStringArray[] = inString.toCharArray();
