Overloading Variable Arguments
Dec 27, 2014
I am going through Thinking in Java, 4th Ed and I came across the section that talks about overloading variable arguments. I tried out a piece of code from the book. (Method and class names not exactly the same).
public class Varargs
{
public static void m1(Character... args)
{
System.out.println("Character");
[code]....
In the above code, the compiler throws an 'Ambiguous for the type varargs' error. The error goes away if the first method is changed to:
public static void m1(char c, Character... args)
why there is ambiguity in the first piece of code and not the second.
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Jun 9, 2014
A method is declared to take three arguments. A program calls this method and passes only two arguments.Will it take the third argument as
1 null
2 void
3 zero
4 Compilation error
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Apr 6, 2014
Can you give me a simple description of what overloading a constructer is?
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Jan 22, 2015
Why the following is happening.
For the below code, when I execute it, it prints
Short method 10 //result 1
Sub class short method 10 //result 2
Which is as expected but if I comment out line 3, then it prints
Integer method 10 //result 3
Integer method 10 //result 4
I can understand result 3 is because of an upcast from short to int, since FunWithOverloading will not have a overloaded method with short now. However, what is happening with result 4? Shouldn't it call methodA of the subclass with the argument type short? If its because I have declared the reference variable, derived, of the type FunWithOverloading, then how come the first result correctly picks the overloaded method of the sub class?
class FunWithOverloading{
void methodA(int x){System.out.println("Integer method " + x);}
void methodA(short x){System.out.println("Short method " + x);} //line 3
} class OverloadedSubClass extends FunWithOverloading{
void methodA(short x){System.out.println("Sub class short method " + x);}
[Code] ....
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Feb 24, 2014
The class Overloading below asks for two names and prints three different greetings. Your task is to write the class methods missing from the class declaration. Methods print the greetings as shown in the example print. The names and parameter types of the needed methods can be checked from the main method because all methods are called there. This exercise also does not require you to copy the source code below to the return field. The method declarations will suffice.
Example output
Type in the first name: John
Type in the second name: Doe
Java Code:
import java.util.Scanner;
public class Overloading {
public static void main(String[] args) {
String firstName, secondName;
Scanner reader = new Scanner(System.in);
[code]....
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Oct 18, 2014
why operator overloading is not supported in Java.
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Apr 23, 2014
What I have done wrong
public class BankAccount
{
String name;
int accountID;
double balance;
public void setAccount( String username, int ID, Boolean isJoint)
[Code] ....
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Feb 24, 2014
The class Overloading below asks for two names and prints three different greetings. Your task is to write the class methods missing from the class declaration. Methods print the greetings as shown in the example print.
Hint:The names and parameter types of the needed methods can be checked from the main method because all methods are called there. This exercise also does not require you to copy the source code below to the return field.
The method declarations will suffice.
Example output
Type in the first name: John
Type in the second name: Doe
**********
Hi!
**********
Hi, John
**********
Hi, John and Doe
**********
import java.util.Scanner;
public class Overloading {
public static void main(String[] args) {
String firstName, secondName;
[Code] ....
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May 4, 2014
I was told to create a class named Billing that includes three overloaded computeBill methods for a photobook store.
The first method takes the price of the book ordered, adds 8% tax and returns the total due.
The second method takes the price of the book, and the quantity, adds tax and returns the total.
The final method takes the price, quantity and a coupon discount, adds tax and returns the total.
All of this I have managed fairly well, although I keep getting a strange error at the end of my program that the constructor is undefined. The problem bits of code(the one throwing the errors) are under the comment //Enter values into each of the methods
Code:
package org.CIS406.lab2;
public class Billing {
//Declarations
double bookPrice;
int quantityOrdered;
double couponValue;
[Code] ....
My first thought was to create a constructor for each of the methods that I am using...
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Feb 11, 2014
I have a case in which I want to sort two types of ArrayLists (using quicksort) and the method originally coded only accepts a String ArrayList. The problem is that now I want to sort an ArrayList of type int but couldn't . . . so I decided to overload the method. Since it looks very ugly to copy and paste the same chunk of code only to change the method signature I wondered if there is a better way to make this method more dynamic and be able to take in different types of ArrayLists.
My code:
private ArrayList<String> sort(ArrayList<String> ar, int lo, int hi){
if (lo < hi){
int splitPoint = partition(ar, lo, hi);
sort(ar, lo, splitPoint);
sort(ar, splitPoint +1, hi);
[Code] .....
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Feb 7, 2015
why Java does not support return type in method overloading. I coded following and it compiles and runs without any errors.
class Ideone
{
public static void main (String[] args) {
sum(3,5);
[code]....
If Java did not support overloading based on return type, this program should not work, right?
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Sep 14, 2014
i have to run my program from the command line...My code is:
public static void main( String[] args )
{
// check command-line arguments
if ( args.length == 2 )
{
// get command-line arguments
String databaseUserName = args[ 0 ];
String databasePassword = args[ 1 ];
[code]....
Now everything works in Netbeans but running it from the command line, i get an error message ".java uses unchecked and unsafe operations".I have added a bit more code to the code above
for (int i = 0; i < args.length; i++) {
System.out.println("args[" + i + "]: "
+ args[i]);
}
Just not sure how to run it from the command line,
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Nov 8, 2014
I am new to JAVA. I need to execute a program, based on the OS. If I am on Mac, the program is a .x and if It is on Windows the program is .exe. The program also requires a line of commands attached to it (i.e. relap5.(x) or (exe) -i inputFile -o outputFile -r restartFile -s stripFile
Here is my coding
String in = " -i ", tfIntdta.getText();
String rst = " -r ", tfRstplt.getText();
String out = " -o ", tfOutdta.getText();
String strp = " -s ", tfStpdta.getText();
if tfStpdta.contains(".csv")
String run = in, rst, out, strp;
else
String run = in. rst, out;
// I want to execute either a .x file or .exe file, depending on if I am
// running the app on windows or mac
run relap5.(x) or (exe) (string run goes here)
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Sep 29, 2014
I have been able to create a no arg constructor and pass empty double, int, and strings but i am not able to pass an arraylist.
class Savings {
private double balance;
private ArrayList <String> transaction = new ArrayList();
public Savings (double B)/>
{
balance = b;
}
public Savings()
{
this(0.0,new ArrayList());
}
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Apr 22, 2015
I am writing a simple program in Java, where I call a method and pass some variables (namely, min and max) as arguments. This method is recursive, so the same arguments are again passed on in each recursive call.
I need to update these variables in recursive calls so that when the calling method uses them, it uses updated values. As it might sound confusing, here is sample code :
// Function 1.
void func1() {
//Call func2.
func2 (int hd, int min, int max, Map<String, String> map);
//Other stuff.
}
// Function 2.
[code]....
As you can see, min and max are updated after each recursive call returns, based on conditions. However, these changes aren't reflected in original min and max, which were used by func1 while calling func2. As far as I know, this happens due to call by value mechanism being used by Java while passing arguments. If I declare min and max as instance variables in the class, my problem is solved. But, I want to know whether there's any other way to update these variables so that changes in original min and max are reflected. Yes, I can return them as an array of 2 elements each time while returning, but it didn't seem a good solution to me.
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Mar 8, 2014
For the object arguments in date formatters such as %td, are only calendar objects accepted?
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Jul 14, 2014
In Java code, write class called Student with the following features:
• a private instance variable int studentNumber that is initialized to zero.
• a private instance variable String firstName;
• a private instance variable String lastName;
• a constructor which takes an integer argument and two String arguments to initializes the three respective data items.
• a public method with signature equals(Student s) . . .
So far this is my code :
public class student {
private int studentnumber = 0;
public student () {
firstname= "forename":
lastname="surname":
public student (integer studentnumber, string firstname, string lastname) {
this.firstname= firstname
this.lastname= lastname:
My question is how do i add the integer in the argument do i have to use int =? and how would i go about doing the public signature equals...
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Apr 6, 2014
I am looking to write a constructor (in a herited class) to initialize the name of a single piece and its orientation using values passed as parameters. If no value is given for guidance , it returns "none" , I do it in this way but i am not sure it is the right way:
public SimplePiece(String piece,String d){
super(piece);
if(d == null){
guidance = "none";
}else{
guidance = d;
}
}
What do you sugger me to do to get the right code .
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May 1, 2014
At the beginning of one of my classes, I instantiate some List objects. For example ...
Java Code: private List<> byName = null; mh_sh_highlight_all('java');
... then later, I reference this again in a method like this:
Java Code: byName = new ArrayList<>(rs.getString("firstName"), rs.getString("Last Name")); mh_sh_highlight_all('java');
This is where I get the error. I've tried making the list of <String>, but that didn't make a difference.
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Nov 14, 2014
I have a test that covers Objects & Classes, Importing Classes and Polymorphism. One of the essay questions will be: Explain two ways to pass arguments to methods and give examples. I was reading the book and found Pass by Value and Pass by Reference. Is this the two ways to pass arguments?
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Oct 18, 2014
I am trying to create an array where each object includes a service description, price, and time in minutes. I have a Service class and a SalonReport class:
import java.util.*;
public class Service
{
public String serviceDescription;
public double servicePrice;
public int timeMinutes;
[Code] ....
When I compile this, I get an error message that says:
SalonReport.java:8: error: constructor Service in class Service cannot be applied to given types;
salonServices[0] = new Service("Cut", 8.00, 15);
^
required: no arguments
found: String,double,int
reason: actual and formal argument lists differ in length
What this error message means and how I can correct it? I am confused because my SalonService() method has (String service, double price, int minutes), and each object is listed in that exact order.
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Mar 1, 2015
What I'm supposed to do is use the time class and take the command line arguments and print them as the start and end times and then calculate the elapsed time between the two. My issue (hopefully my only as I have been working on this all day now) is that I cannot call the command line arguments using LocalTime. Below is what I have so far.
import java.time.Duration;
import java.time.LocalTime;
public class Clock {
private LocalTime startTime;
private LocalTime stopTime;
//default constructor-initialize startTime to current time
public Clock(){
this.startTime=LocalTime.now();
[Code] ......
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May 21, 2014
Given the case I have an object which is assigned only once. What is the difference in doing:
public class MyClass {
private MyObj obj = new MyObj("Hello world");
private MyClass(){}
//...
}
and
public class MyClass {
private MyObj obj;
private MyClass(){
obj = new MyObj("Hello world");
}
//...
}
Is there a difference in performance or usability? (Given also the case there are no static calls expected) ....
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Oct 27, 2014
The term "Local variable" is related to scope. That is a local variable is one which is defined in a certain block of code, and its scope is confined inside that block of code.And a "Member variable" is simple an instance variable.
I read in a discussion forum that when local variables are declared (example code below), their name reservation takes place in memory but they are not automatically initialized to anything. On the other hand, when member variables are declared, they are automatically initialized to null by default.
Java Code: public void myFunction () {
int [] myInt; // A local, member variable (because "static" keyword is not there) declared
} mh_sh_highlight_all('java');
So it seems that they are comparing local variables and member variables. While I think a member variable can also be be local in a block of code, isn't it?
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Feb 5, 2015
I want to take command line arguments and pass them to a paint method. This is a test program that will just draw some equations. How can I get the input array clinputs[] to be used in public void paint( Graphics g) ?
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class LinePlot extends JFrame {
public LinePlot() {
super( "Line Plot" );
setSize(800,600);
[Code] .....
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Jun 5, 2014
I am totally new to Java. What is the purpose of this method?
Flow of the int x=3; like where does the 3 go step by step?
Passing Primitive Data Type Arguments (from oracle java tutorials)
Primitive arguments, such as an int or a double, are passed into methods by value. This means that any changes to the values of the parameters exist only within the scope of the method. When the method returns, the parameters are gone and any changes to them are lost. Here is an example:
public class PassPrimitiveByValue {
public static void main(String[] args) {
int x = 3;
// invoke passMethod() with
// x as argument
passMethod(x);
[Code] ....
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