Null Detected In String Array Not Saved By Class Constructor
Mar 12, 2014
I've a vertical-bar-delimited file where most elements contain text, some contain whitespace, and some are empty. Examples:
62RG|fe|Pencil Financial Group, LLC||doug@pencil.com|||85637889|Cross, Ben|bcross@godaddy.net|Bernard|Cross|Ben||315 One Tree Hill Terrace|Lafayette|LA
62RG|fe|Pencil Financial Group, LLC||tracy@pencil.com|||13658734|Dustin Cardwright|dcart@motorola.com|Dustin|Cartwright|||| |LA
which I parse and store with
String str_arry = innline.split( "|", 17);
lisst.add( new Contact( str_arry));
and my Contact class has the constructor
public Contact( String[] str_arry) {
for( int ii = 0 ; ii < str_arry.length ; ii++ ) {
if( str_arry[ii].matches("^s+$")) {
str_arry[ii] = null;
System.out.println("hit a null");
[Code]...
I expect the for-loop in the constructor to find any elements containing whitespace characters and set them to null for subsequent assignment.And when the code runs I do see some hit-statements pop up, so the detecting part is working.
But when I then process the list and access a Contact object and test fields for nulls I don't find any ie
if( aContactObj.getfFCity() == null) System.out.println("city is null");
never prints when it should.
What's the trick? Or is my approach wrong and if so what should it be?
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Mar 8, 2015
I have a class of Date with a constructor with 3 parameters in it. Those 3 parameters are int data type just to enter month, year, day.
I have another class called Author which has a constructor of Date diedDate; as a parameter passing to the Author constructor.
I was asked to call the Date parameter is null, call the default constructor but I thought for the Date parameter I could only enter something like 0,0,0 instead of typing in null, null, null because null is for String data type isn't it?
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Sep 15, 2014
So I need to write a program that reads through a String and counts how many vowels there are and prints them out as it finds them. This is what I have so far:
if (vowel == 'a' || vowel =='e' || vowel =='i' || vowel == 'o' || vowel == 'u'){
numberOfVowels++;
}
The problem is that I can't figure out how to print out the character once it detects it as a vowel.
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Jun 8, 2014
Question 1: I am working on an assignment where I have to remove an item from a String array (see code below). When I try to remove an item after entering it I get the following error "java.lang.NullPointerException." I am not sure how to correct this error.
Question 2: In addition, I am having trouble figuring out how to count the number of occurrences of each string in the array and print the counts. I've been looking at other posts but they are more advanced and I have not yet learned how to use some of the tools they are referring to.
private void removeFlower(String flowerPack[]) {
// TODO: Remove a flower that is specified by the user
Scanner input=new Scanner(System.in);
System.out.println();
System.out.println("Please enter the name of the flower you would like to remove:
[Code] ....
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Sep 7, 2014
I'm getting constructor null pointer exception but i don't know what has gone wrong...
private int capacity; // maximum capacity of the board
private double minimum; // minimum distance of the flyer
private SortedLinkedList sortedList;
private int size = 0;
public ScoreBoard() {
capacity = 10;
minimum = 0.0;
sortedList = new SortedLinkedList();
[Code] ....
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Aug 28, 2014
can we pass private final class object to another class constructor?
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Aug 1, 2014
So i declared a class in main class but it seems there's error when i compile:
constructor xx in class xx cannot applied to given types
This is my java class:
public class trainer extends person{
String classType;
public trainer(String name, String gender, String address, int id, String classType) {
super(name,gender,address,id);
this.classType=classType;
[Code] ....
And this is the way i declared in main class:
trainer tr = new trainer();
And what i want to do is:
tr.toString();
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Feb 7, 2014
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
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Apr 8, 2014
I have a school assignment that involves me sorting an array of objects based on one of the class String variables. I am using as the title says a simple selection sort method. The problem I'm having is that when I run the program in debug mode, it never seems to enter the if statement in the inner loop. I would like to say I've tried a number of things to figure it out, but honestly I'm just stumped as to why it's not working.
Here is the code:
public static void sortTransactions(Transaction[] oTransaction){// This is the sorting method, obviously it's not done so it currently just prints to screen.
System.out.println("Successful call to sortTransaction()");
String min = "";
int curInd = 0;
Transaction[] temp = new Transaction[1];
[Code] ....
The output when I check to see if the array is sorted verifies that the array never does get sorted.
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Sep 22, 2014
Trying to make me understand when to initialize a string 'null' and when not..??
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Jan 16, 2014
static public String populateVehicleDetails(Vehicle vehicle){
String returnString = new String()
String existingString = "Chevy Uplander "
String nl = "
"
returnString.concat(existingString+nl).
concat("Color: "+ vehicle.color + nl)
return returnString
}
In the case that vehicle.color is null what will happens? A null pointer error?
null will be concatenated to the string in vehicle.color place? or will not concatenate anything in the place of vehicle.color I'm asking that because I do not know if I have to check for null in each property of vehicle that I must concatenate (there are a lot of properties in the Vehicle object and some may not been set (they will return null).
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Oct 13, 2014
I've been beavering away with Java for a few months. But as with all languages the String implementation looks designed to trip up even experienced programmers.
My current development gets data from various sources outside my control. When I get a string I want to test if it is empty/null/or whatever. Simple enough one thinks.
But if you search the internet you see everone seems to have a slightly different approach. So what is the best way of determining that a string is not useful to you?
I've had success with this
if(string == null || string.length() == 0)
But I've seen people using methods - not necessarily of String (e.g equals, empty) and regular expressions.
What is the best approach to this considering coding efficiency and/or processing efficiency (accepting you'd have to be processing a lot of strings for the latter to be an issue).
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Aug 5, 2014
In Java is there a method which I can use to compare two Strings where in if both the values are null, they should be considered as equal?
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Jul 23, 2014
I have saved emails that are stored in to text files and I want to retrieve the Sender, Reciever, Subject and the Email Content.I am using From: as a delimiter and To: as a delimiter and Subject as a delimiter and I am not sure what delimiter I should set for the email content.Also, there can be emails that will have comments after the message content and I plan on using the delimiter Comments:.
Any example of what delimiters I should use it would be great. Also I would like to know how check whether or not a delimiter exists so that I can print out the comments if it exists and if the file does not have comments, it prints out nothing.
import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;
[code].....
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Jun 26, 2012
I want to create a online examination system.i want to know to how to get questions 1 by 1 on the same jsp page and on clicking the submit button the result should be saved in database.
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Jun 23, 2014
Do we have constructor in abstract class? If we have then what is the use of it?
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Feb 24, 2015
I have table data I'm trying to read . However one column is populated with the word "null". I guess java does not like dealing with the word null and throws errors.
When I try a block like : if ( rsrow.getString(insCol) = "null") {
I get and error .
If I try :
cmp = rsrow.getString(insCol);If I try:If I try:
if (cmp = "null") {
I get an error
If I try to use a replace function like:
System.out.println(cmp.replace("null", "0"));
Just to see if replace works I get and error.
What is the BEST way to replace this string value with something like "0" when I come across it with out jave throwing an error? I want it such that every time I come across the word "null" I can repalce it with "0".
Something like:
if (rsrow.getString(insCol) = "null") {rowofdata = rowofdata + "'0',"; } else {rowofdata = rowofdata + "'" + rsrow.getString(insCol) + "',";}
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Feb 28, 2015
I have to create a constructor with eight parameters containing both string and integers.the variables were supposed to be entered by user. but when I try to create an object of the class the IDE post error messages about the constructor.
public class hfiledriver {
//the class name is hfile
//after the main method I try creating an object of the class
//after prompting the user to enter the data
hfile hfile= new hfile(firstname, lastname, gender, age, weight, height);
}
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Feb 13, 2015
This code works
public class RedShapeDecorator extends ShapeDecorator {
public RedShapeDecorator(Shape decoratedShape) {
super(decoratedShape);
}
Below results in an error
public class RedShapeDecorator extends ShapeDecorator {
protected Shape decoratedShape;
public RedShapeDecorator(Shape decoratedShape) {
this. decoratedShape=decoratedShape;
}
So I am guessing that if you extend class, you should use super to pass objects?
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Oct 21, 2014
I am writing a program that should take a url and scan the page for any links. It is in the beginning stages, but I ran into an error when I tried to extend a class. There's a lot going on in this code, but the error is caused by the constructor.
Error message at compile time:
"constructor Page in class Page cannot be applied to given types;
{//Constructor
^
required: String
found: no arguments
reason: actual and formal argument lists differ in length".
Here's the code(first my class, then the class I extended)
public class SearchEngine extends Page {
public static Color customGreen = new Color(69, 194, 33);
public static Color customYellow = new Color(232, 166, 12);
public static Color customBlue = new Color(25,97,255);
public static Color customYellowComp = new Color(178,125,0);
[code]...
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Jan 7, 2014
When creating a class with a constructor, why does one have to create private variables (attributes) to be used as parameters by the object? The object's parameters will be set to be exactly equal to the private variables (attributes), so what is the point of having the private variables (attributes) Why are both private variables (attributes) and parameters needed when they are set to be equal each other anyway?
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Feb 4, 2015
Below Code
abstract class A
{
A(int a, int b)
{
}
}
If we can't create objects for abstract class, what is the need of writing constructor???
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Nov 7, 2014
The game doesn't seem to be working but you can win by loading a winning saved game.
Hint: Remember that all numbers have a unique set of Prime Factors.
I have been struggling to solve this. The code is not in error. I am trying to load a winning file but unable to solve.
Here is the java code:
import java.math.BigInteger;
import java.util.ArrayList;
import java.util.HashSet;
import java.util.Random;
import java.util.Scanner;
import java.util.Set;
public class Main {
static final int GAME_SIZE = 40; //Disk sizes go from 0->39
// Produce a list of the first N prime numbers
[Code] ....
Results:
C:UsersSal_2>java Main
Welcome to Towers of Toast!!!
Type 'new' to start a new random puzzle
Type 'load' to load a saved puzzle
new
[0, 2, 3, 4, 5, 6, 8, 10, 14, 19, 20, 25, 26, 28, 35, 38, 39]
[7, 9, 11, 13, 15, 21, 22, 23, 27, 31, 32]
[1, 12, 16, 17, 18, 24, 29, 30, 33, 34, 36, 37]
|
|
XX |
|
XXX |
|
XXXX |
|
XXXXX |
|
XXXXXX |
X
XXXXXXXX XXXXXXX
XXXXXXXXXXXX
XXXXXXXXXX XXXXXXXXX
XXXXXXXXXXXXXXXX
XXXXXXXXXXXXXX XXXXXXXXXXX
XXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXXX XXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXXXX XXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
The game is broken! We saved your game, though. Here are your save game numbers:
146209709250387100944095470
52067710192022655041
21882855117530023387473
C:UsersSal_2>java Main
Welcome to Towers of Toast!!!
Type 'new' to start a new random puzzle
Type 'load' to load a saved puzzle
load
Enter save number for pole 1:
3
Enter save number for pole 2:
1
Enter save number for pole 3:
11
Exception in thread "main" java.lang.RuntimeException: Not all disks accounted f
or
at Main.main(Main.java:100)
C:UsersSal_2>
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Nov 5, 2014
How do you test a default constructor in one class and then test it in a different class? This is the code for the Person class which has the default constructor. I'm not sure in the PersonTester class how to access this default constructor and how to test it - what I have so far for the second class is also below.
class Person {
// Data Members
private String name; // The name of this person
private int age; // The age of this person
private char gender; // The gender of this person
[code]...
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Jul 15, 2014
I am following this article : [URL] ....
It is important to note that the inference algorithm uses only invocation arguments, target types, and possibly an obvious expected return type to infer types. The inference algorithm does not use results from later in the program.
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Feb 28, 2014
The one problem in my book was to create a constructor for different shirt features, which I did and ran successfully. Out of curiosity, I also added other methods to see if it would run if the parameters were different from the constructor. It keeps giving me a constructor error. So, my question is, am I able to create a class that uses a constructor with parameters and other methods without errors? I'm guessing there's no reason to since it would be wasted space since the constructor could do it but was just curious if it's possible.
Is everything from the constructor down (in the class) and Shirt.oneShirt (in the main) just a waste of time?
Here's my example:
public class Shirt//class name.
{
int collarSize;//data field.
int sleeveLength;//data field.
int pocketNumber;//data field
public final static String MATERIAL = "cotton";//final data field for material.
public Shirt(int collarSize, int sleeveLength, int pocketNumber)//start of constructor.
{
[Code]...
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