Type Inference With Constructor Of Generic Class

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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How To Convert String Type To Generic Class Type

Mar 22, 2015

I have a String repersentaion of some Object.I want that object convert back into some class type how can I do this?

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Type Class Is Not Generic - It Cannot Be Parameterized With Arguments

May 16, 2008

I have set up a project in Eclipse 3.1 and am using java 5.0 compiler.

Here's my folder structure in Eclipse

Java Code:

DFSRemoteClientTestClient.java mh_sh_highlight_all('java');
DFS is the project in Eclipse

And this is how it looks my java class

Java Code:

package RemoteClient;
import java.util.*;
// other imports
public class TestClient {
public static void main(String [] args) throws ServiceInvocationException {
// business logic here ....
}
} mh_sh_highlight_all('java');

So, basically, my java class is just a simple class with a main function.

Now when I build my project, using Project->Clean...

Then I get this as an error at the very first line where i specify the package

This is the error:

Java Code: The type Class is not generic; it cannot be parameterized with arguments <T> mh_sh_highlight_all('java');

What's this error and why am I getting this.

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Addition Of Generic Type Parameter Causes Member Type Clash

Apr 22, 2014

Got a problem with generics, which I'm still pretty new at. Here's a program that compiles fine:

import java.util.ArrayList;
import javax.swing.JComponent;
public class Experiments {
public static void main(String[] args) {
ListHolder holder = new ListHolder();

[Code] ....

It's useless, but it compiles. If I change Line 14, however, to add a generic type parameter to the ListHolder class, Line 10 no longer compiles:

import java.util.ArrayList;
import javax.swing.JComponent;
public class Experiments {
public static void main(String[] args) {
ListHolder holder = new ListHolder();

[Code] ....

I get this error:

Uncompilable source code - incompatible types: java.lang.Object cannot be converted to javax.swing.JComponent
at experiments.Experiments.main(Experiments.java:10)

Apparently, the introduction of the type parameter leaves the compiler thinking that aList is of type Object. I can cast it, like this:

JComponent c = ((ArrayList<JComponent>)holder.aList).iterator().next();

That makes the compiler happy, but why is it necessary? How does adding the (unused) type parameter to the ListHolder class end up making the compiler think the aList member of an instance of ListHolder is of type Object?

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Generic Method In Generic Class

Jul 23, 2014

1 import java.util.ArrayList;
2 import java.util.List;
3
4 public class MyList<E> {
5
6 public List<E> list;
7 public int length;

[code]...

I am trying to define a class MyList, which i just a wrapper around an ArrayList, no real purpose, just for the sake of learning Generics. Idea here is that I create a parameterized class, MyList<E>, which holds a parameterized instance var of type List<E>. I have an add method which adds an element of type E to the List<E>. If I create an instance of MyList, call it 'm', for some reason when I try to call a method on that instance the compiler complains that 'm' cannot be found.

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Interfaces Using Generic Type Constructions

Jan 16, 2014

I want to make some library interfaces for a graph.Using these interfaces:

Graph<V,E>
Edge<E>
Vertex<V>

how can i constraint users of this library to use the same type <E> in the graph and edge interface and type <V> in the graph and vertex interface??

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Generic Methods Introduce Their Own Type Parameters

Apr 10, 2014

Generic methods are methods that introduce their own type parameters. This is similar to declaring a generic type, but the type parameter's scope is limited to the method where it is declared. Static and non-static generic methods are allowed, as well as generic class constructors.

1. The method is only exclusively to be used for the declared argument parameter? For example given a generic method:public static <String, Integer> boolean method(Pair<K, V> p1) {}I could only invoke the method if Pair argument parameter is <String, Integer>?

2. Or, it will return a <String, Integer> value?

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Adding Any Type Of Data To A Generic List?

Aug 28, 2014

Is this the proper way to add to a generic list? My code works just fine, but I got this feeling that there might be some kind of flaw in it or something. Is this pretty much the basic way to add any type of data to a generic list?

import java.util.LinkedList;
public class ListOfGeneric<E> {
private LinkedList<E> myList;

ListOfGeneric(){
myList = new LinkedList<E>();

[Code] ....

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Generic Method And Bound Type Parameter Errors

Jul 14, 2014

I am following this article [URL] .... till now I have made some code

This is my Interface

public interface Comparable<T> {
public int compareTo(T o);
}

And this is my class where I am using Bound Type Parameter on Generic Methods

public class GenericMethodBoundType {
public static <T extends Comparable<T>> int countGreaterThan(T[] anArray, T elem) {
int count = 0;
for (T e : anArray)

[Code] .....

What else I need to do both in main method and at what parameterized types I need to pass at the class?

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Cannot Assign Generic Object Reference To Similar Type

Jul 26, 2014

I have the following code:

public class CollisionManager<T> {
private boolean collision = false;
private T mainEntity;
public <T extends Entities> void handleCollision(T mainEntity, T secondEntity){
this.mainEntity = mainEntity; // This is illegal.
}
}

Why "this.mainEntity = mainEntity" is incorrect and also show me the correct way to achieve this?

The error I am getting is "Type mismatch: cannot convert T to T"

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Cannot Assign Cloned String Array To Generic Type Array

Jun 21, 2014

I have the following code in which I am looping through the rows of one array (composed of Strings) and copying it to another array. I am using .clone() to achieve this and it seems work as it changes the memory location of the rows themselves. I did notice that the String objects are still pointing to the same location in memory in both arrays but I won't worry about that for now, at the moment I just want to understand why the array I am cloning is not successfully assigning to the other array.

This is the incorrect line: ar[r] = maze[r].clone();

My code:

private String[][] maze = {{"*","*","*"," ","*","*","*","*","*","*"},
{"*"," ", "*"," "," "," ","*"," ","*","*"},
{"*"," ","*","*","*"," ","*"," ","*","*"},
{"*"," "," "," "," "," "," "," "," ","*"},
{"*","*","*","*","*"," ","*","*","*","*"},
{"*","*","*","*","*"," ","*","*","*","*"}};
//private String[][] mazeCopy = copyMaze(new String[6][10]);
private <T> T[][] copyMaze(T[][] ar){
for (int r = 0; r < ar.length; r++){
ar[r] = maze[r].clone();
}
return ar;
}

My compiler says: Required: T[]. Found: java.lang.String[]

Since ar[r] is an array and .clone() also returns an array why is this line incorrect.

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Cannot Fit Generic Class To Use With Foreach

Oct 7, 2014

I've implemented Stack on the base of the LinkedList. It works as i expect it to work, but then i tried to made it compatible with foreach loop. I've implemented Iterable and Iterator. Code compiles and works fine, but does not return any output. It looks like while working with foreach, next() is not called at all. If i`m getting iterator from instance and try to do iterator.next(), i get output as expected.

public class genericStack<T> implements Iterator<T>, Iterable<T> {
private LinkedList<T> LL ;
protected genericStack() {
this.LL = new LinkedList<T>();
}
public static void main(String[] args) {

[Code] ....

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How To Convert Input Array Of Type Strings To Class Type

Aug 14, 2014

class Passenger{
String name;
int age;
char gender;
int weight;
public Passenger(){

[Code] ....

This is showing error.....error it gives isthat it cannot change from string type to passenger type......... How to do it??????

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Sort 2 Different Objects In Self Made Generic Class Using Comparator

May 31, 2014

Ok here are my 2 Classes

Both have Identical Fields

package com.Lists;
public class EmployeeOffice implements EmpInterface {
private double salary;
private String name;
private String postion;
private double hoursWorked;

[Code] .....

So if i wanna sort this Generic class using comaparator what do i do... I cant find an answer to this... I wanna sort them on the basis of salary what to do ...

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Pass Private Final Class Object To Another Class Constructor

Aug 28, 2014

can we pass private final class object to another class constructor?

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Declaring Class In Main Class - Constructor Cannot Applied To Given Types

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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Creating New Constructor In Child Class Which Is Not In Parent Class

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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Constructor In Abstract Class?

Jun 23, 2014

Do we have constructor in abstract class? If we have then what is the use of it?

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Constructor In A Class Cannot Be Applied To Given Types

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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Constructor Error When Extending A Class?

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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Private Variables In Class / Constructor

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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Writing Constructor In Abstract Class

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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How To Test Default Constructor In Different Class In Java

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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Create Constructor With Parameters And Methods In Same Class?

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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LightController And Circle Class - Creating A Constructor

Jan 6, 2015

I have two classes LightController & Circle. I need to use the LightController class to do the following:

Creates an instance of Circle with a diameter of 50 and a colour of OUColour.GREEN and assigns this new circle to the instance variable light.

Sets the xPos of light to 122.
Sets the yPos of light to 162.

I am struggling to write the correct line of code to set the colour to green and set diameter to 50.

Code for the two classes below.

001
import ou.*;
002
import java.util.*;
003
/**
004
* Class LightController
005
* This class uses the Circle class, and the Shapes window

[Code] ......

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How To Create Object To Be Null If Class Constructor Parameter Is Int

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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