Redefine FileNotFoundException By Creating A New Class Which Extends It
Mar 25, 2015
I am trying to redefine the FileNotFoundException by creating a new class which extends it, but I am having difficulty. For my class practice, if no file is selected or passed in, an UnknownFileException should occur.My code is the following:
Java Code:
import java.io.FileNotFoundException;
public class UnknownFileException extends FileNotFoundException {
public UnknownFileException() {
super("We couldn't tell what file this is");
}
public UnknownFileException(String message) {
super(message);
[code]....
But I get a compile error stating an unreported FileNotFoundException.
I'm building a text editor. At this point, the editor should be able to read and write text and rich text. I create an instance of a RichTextEditor class that I created that extends a superclass I created (that extends JTextPane). Both my rich text and plain text classes extends the superclass I created. I use the this.read() to input my plain text from buffered reader. I think I need to use the read(fileinput stream, rtf document) method from type RTFEditorKit, but I cannot use that because it does not extend RTFEditorKit. I don't want to create a new class that extends RTFEditorKit because I need stuff from the JTextPane.
here are the classes on git... the super: TextEditorPane.java
The plaintext: TextEditorWrap.java
and the rich: RichTextEditor.java
I have fiddled with the read() method in different ways. In all cases, nothing loads. If I use the BufferedReader method, it doesn't give me an RTF, just the code for the RTF file.
How should I proceed? Do I create some sort of RTF interface and implement it?
import javax.swing.JFrame; public class groupingTest { public static void main (String[] args) { groupWindow test = new groupWindow();
[Code]....
At the start of the groupWindow it turns yellow and it says "The serializable class groupWindow does not declare a static final serialVersionUID field of type long".
public class Color { private int red; private int green; private int blue; public Color(){ red = 0; green = 0; blue = 0; }
And i have the Light class :
public class Light { private Color color1; private boolean switchedon;
public Light(int red, int green, int blue){ //dont know what to write here . how can i use the members of the Color class here ? without using extends. } }
I am working on a project where i need to show a year value in a class that extends JSpinner.Its working just fine but when i try to set an alignment value for the editor textfield it all falls apart and i know im missing something really critical here but i can't see or find it all i know is that i can't make a proper reference to the textfield component in the editor i use in the correct way or aproach.
public class JNumberSpinner extends JSpinner { private String actionCommand; private boolean isEnabled; private int startValue; private int columns; private int alignment; private SpinnerNumberModel model; private JSpinner.NumberEditor numEditor; private JFormattedTextField jTxtEditorView;
When I try to run the programm, it always throws a FileNotFoundException, algthough the file exists in the same folder as the project. I tested it with the canRead() method and it returned false, but I can't figure out why it can't read from the file
package sumOfFloats; import java.io.File; import java.io.FileNotFoundException; import java.util.Scanner; public class SumOfFloats {
I'm a Java beginner and I've been trying to scan a file using the Java Scanner. I've tried searching online for this error and I only find people's questions who have entered an incorrect relative path. I'm entering in an absolute path and I'm using Eclipse Standard Edition on a 2013 MacBook Pro with Mavericks 10.9.2.
Anyway, the error message I'm receiving on Eclipse is: Exception in thread "main" java.lang.Error: Unresolved compilation problem: Unhandled exception type FileNotFoundException
at App.main(App.java:12) public class App { public static void main(String[] args){ String fileName = "/Users/Student/Documents/index.html";
[code]...
Why it cannot find this file. I've checked the absolute file path of index.html on my Mac and I've copied and pasted it into my code.
Design a class named Person and its two subclasses named Student and Employee. Make Faculty and Staff subclasses of Employee. There is also a MyDate class as explained below. A person has a name, address, phone number, and email address. A student has a status (freshman, sophomore, junior, or senior). Define the status as an integer which can have the value 0 (for "Freshman"),
1 (for "Sophomore"), 2 (for "Junior"), and 3 (for "Senior"),
but don't allow the status to be set to any other values. An employee has an office, salary, and dateHired. The dateHired is a MyDate field, which contains the fields: year, month, and day. The MyDate class does not explicitly inherit from any class, and it should have a no-arg constructor that sets the year, month, and day to the current year, month, and day. The MyDate class should also have a three-argument constructor that gets three int arguments for the year, month and day to set the year, month and day.
A faculty member has office hours and a rank. Define the rank as a String (for values like "Professor" or "Instructor"). A staff member has a title, which is also a String. Use data types for the fields as specified, or where one is not specified, use a data type that is appropriate for the particular field. Write a test program called TestEveryone.java that creates a Person, Student, Employee, Faculty, and Staff object, and invoke their toString() method (you don't need to call the objects' toString() method explicitly).
Note: Your MyDate.java class is the object class that your dateHired field is created from in the Employee.java class.
Do not use the Person, Employee or Faculty classes defined on pages 383 and 384 of the book. Create new ones.Here is the code I have so far concerning the employee and MyDate.
public class Employee extends Person { private String office; private double salary; //private MyDate dateHired; //7 argument constructor for employee public Employee(String name, String phoneNumber, String email, String address, String office, double salary /*MyDate dateHired*/) { super(name, phoneNumber, email, address);
I've a parent class with a argument constructor like below(a sample code)
public class Parent { Parent(String name) { System.out.println(name); } public static void main(String[] args) { } }
Also I've child.class which extends Parent.class as shown below,
public class child extends Parent { child(String name) { super(name); } }
Now, I want create/modify the constructor which is in child, by taking "int i" as an input instead of "String name". How can I do that? Run time I want to execute child constructor not a parent constructor.
Condition is: Without making any changes to the Parent class
In the process of creating a new class, I need to move my main method from the class SaveDate to the class DynamicTest. Below I have listed the code of both classes.The objective is to be able to run my program from the DynamicTest Class. I need understanding the process of moving my main method to a different class and creating an Object of a class and calling its method.
public class SaveData { private static final Map<String, Object> myCachedTreeMap = new TreeMap<String, Object>(); public static final List<String> getLines(final String resourceParam, final Charset charset) throws IOException{ System.out.println("Please get: "+resourceParam); if (myCachedTreeMap.containsKey(resourceParam) ) { // Use the cached file, to prevent an additional read.
I have an Abstract Class called GameColorEffect which contains a number of non-static Inner Classes that extend their Parent Class, GameColorEffect. I want to be able to create instances of the Inner Classes, however my IDE, eclipse, prompts me with the error:
No enclosing instance of type GameColorEffect is accessible. Must qualify the allocation with an enclosing instance of type GameColorEffect
And eclipse shows me a possible solution which is to turn the Inner Classes to static, this would allow me to create instances, but not really. This is because using methods from the static Inner Classes that change values in the Inner Classes will do this for every instance of the same Inner Class which is literally like a single instance. However, I want these Inner Classes to be individual with their values and still be able to use them outside as instances. I've found out a possible solution, which I'm not sure works like I want it to:
Java Code : GameColorEffect = new GameColorEffect.ExampleEffect(); mh_sh_highlight_all('java');
However, this is in-compact because sometimes all I need is to use just a method like:
Java Code : new GameColorEffect.ExampleEffect(intensity).applyEffect() mh_sh_highlight_all('java');
And another solution that I already knew prior was that I could make the Inner Classes proper classes not inside of the GameColorEffect class, but this is also in-compact because I will have to have so many classes for the so many effects that I have.
Why java uses the keyword extends when setting the bound of a type parameter(Generic) to an interface. I think using the keyword implements is more intuitive.
public static <T extends Comparable<T>>
why use extends? and not implements.
int countGreaterThan(T[] anArray, T elem) { int count = 0; for (T e : anArray) if (e.compareTo(elem) > 0) ++count; return count; }
I know if I want to set multiple bounds I will use extends keyword, and I will concatenate the bounds using & operator.
Is this a design decision to always use extends keyword to set bounds?
I'm not sure why, but whenever I try to get a value out of a double, it only extends to one decimal place. For instance, (825 / 805) would become 1.0000 (after being run through a DecimalFormat object) instead of 1.0248 like I need it to be (and should be if what I know about primitive variable types is right). Why is the double variable type not giving me the precision I want and, more importantly, how do I fix this?
So I'm still trying to get to grips with Java, and like to understand exactly why I'm doing something, so that I am not just regurgitating the code, If I want to create an object from class "Apples", I would use the following, right?
Apples MyAppleObject = new Apples();
From what I understand, MyAppleObject is the new object name, new -> creates a new instance of it in memory, and Apples() is the onCreate method that is called
So question 1: (just a quick aside question) Can I create an object without calling Apples()? i.e.
Apples MyAppleObject = new;
Question 2: - PARTLY SOLVED - I discovered that (Button) is a way of typecasting, so I understand that line a little better. What I don't understand is why we don't need to initialize the object with "new"
I've now looked at a bit of android development and xml and those declarations are all together different, and I'm not sure why. I haven't found a single explanation for the difference in format.
Java Code:
Button Add; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); Add = (Button) findViewById(R.id.button1); mh_sh_highlight_all('java'); So the Button object is declared above the onCreate method, but initialized afterwards I guess....
But instead of using Button Add = new Button() they use Add = (Button) findViewById(R.id.button1);
Question 3:
then In XML they use the following:
Java Code:
public*static*void*main(String[] args){ ********* ********// Creates a DOM object in memory. Now you can access ********// data in the xml file ********* ********Document xmlDoc = getDocument("./src/tvshows5.xml"); mh_sh_highlight_all('java');
Once again, why didn't they have to use : Document xmlDoc = new Document()
package Threads; // THIS PROGRAM WILL HAVE TWO THREADS i.e. "main" AND ANOTHER THREAD (SYSTEM WILL NAME IT "Thread-0" //THE STORY IS THAT WE WILL START Thread-0 FROM main AND LET IT EXECUTE. //main WILL WAIT AND LET IT EXECUTE FOR 5 MINUTES. //IF IT FINISHES ITS EXECUTION BEFORE 5 MINUTES, WELL AND GOOD; //BUT IF IT DOESN'T, WE WILL INTERRUPT IT. //AFTER INTERRUPTION, WE WILL DECIDE TO WAIT INDEFINITELY.
public class SimpleThreadsCopy { public static void threadMessage(String s){ String sThreadName= Thread.currentThread().getName(); System.out.format("%s: %s%n", sThreadName, s);
[Code] ....
The statement against which I have written many *'s gives the following error.
No enclosing instance of type SimpleThreadsCopy is accessible. Must qualify the allocation with an enclosing instance of type SimpleThreadsCopy (e.g. x.new A() where x is an instance of SimpleThreadsCopy).
Now that a similar "error-free" code is given here, what's wrong with this piece of code and what should I do about it?
Trying to understand the error statement, I replaced the erroneous statement with
Java Code : Thread t= new Thread(new SimpleThreadsCopy().new MessageLoop()); mh_sh_highlight_all('java');
And the error got fixed. From that I understand that the inner class is just kinda a nonstatic member of the outer class and it will be accessed by the objects of the outer class only.
But then why doesn't the code in the tutorial give an error?
package home; import java.awt.Color; import java.awt.Graphics; import javax.swing.JFrame; import javax.swing.JPanel; public class Box{ int x=70; int y=70;
[Code] ....
L a = new L(); causing the error. It will be great to know why it is showing error.
public class Person { protected static int MAX_AGE = 150; protected static int MIN_AGE = 0; private static final String VALID_WORD_REGEXP = "[a-zA-Z]{3,30}"; private String firstName; private String lastName;
[Code] ....
I'm trying to learn right way how to throw exceptions. I
Besides that I have couple questions:
I can't quite understand throws statement. I'm thinking throws statement is for passing exceptions one level higher(with are not cought in this caller function). So that would mean I need to put throws in this function only:
Java Code: Person(String firstName, String lastName, int age) mh_sh_highlight_all('java');
Am I right or wrong and is there any other use for it? If so that would mean when
Java Code: Person person = new Person(.....) mh_sh_highlight_all('java');
Is it good practice to create a inner class for layered panels with lots of components? In my opinion this makes the code easier to read and a lot less clustered.
I am trying to get the average of 3 different fraction arrays. I made a fraction class and I made methods such as read() and average() in this new class.
package fractions; import java.util.Scanner; import java.util.Arrays; public class FractionArrays { public static void main(String[] args) { Fraction completeFraction = new Fraction(5,6);
[Code] ....
I was wondering if there was any way to use the arrays I created in the read method in the average method. If I find that out I should be able to do it on my own. Is there a way to make the arrays public to use in different methods?
I have to create an application that deals with maps.
I first have to create the instance variables for the class.
So very simply if my hashmap is going to consist of football clubs and players. Football clubs being a string value for the key and players being a set of strings for the values. How would I go about creating the instance variable in a class for this?
I can't seem to find anything that specifically deals with instance variables and constructors for maps.
public String firstName() Returns the customer's first name public String lastName() Returns the customer's last name public double balance() Returns the customer's account balance
Finally I need to create a driver to test my class. And create several accounts and verify that the first name, last name, and balance methods work properly. This is my code below.. I don't know if I did it right.
public class BankAccount { String firstName, lastName; double balance; public BankAccount(String firstName, String lastName, double balance) {
What is the difference between extending JFrame in one class and simply constructing a new JFrame object in that same class? What benefits do I have with each solution, providing I want to use that class to create the GUI. Is it the same or are there differences rather than not having to reference to a new JFrame to be able to use its functions?
