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.

View Replies


ADVERTISEMENT

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?

View Replies View Related

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.

View Replies View Related

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?

View Replies View Related

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.

View Replies View Related

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??

View Replies View Related

Cannot Infer Type Arguments For ArrayList

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.

View Replies View Related

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?

View Replies View Related

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] ....

View Replies View Related

Passing Primitive Data Type Arguments

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] ....

View Replies View Related

Passing Reference Data Type Arguments

Oct 21, 2012

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.

Reference data type parameters, such as objects, are also passed into methods by value. This means that when the method returns, the passed-in reference still references the same object as before. However, the values of the object's fields can be changed in the method, if they have the proper access level.For example, consider a method in an arbitrary class that moves Circle objects:

public void moveCircle(Circle circle, int deltaX, int deltaY) {
// code to move origin of
// circle to x+deltaX, y+deltaY
circle.setX(circle.getX() + deltaX);
circle.setY(circle.getY() + deltaY);

// code to assign a new
// reference to circle
circle = new Circle(0, 0);
}

Let the method be invoked with these arguments: moveCircle(myCircle, 23, 56)

Inside the method, circle initially refers to myCircle. The method changes the x and y coordinates of the object that circle references (i.e., myCircle) by 23 and 56, respectively. These changes will persist when the method returns. Then circle is assigned a reference to a new Circle object with x = y = 0. This reassignment has no permanence, however, because the reference was passed in by value and cannot change. Within the method, the object pointed to by circle has changed, but, when the method returns, myCircle still references the same Circle object as before the method was called.

View Replies View Related

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?

View Replies View Related

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"

View Replies View Related

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.

View Replies View Related

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] ....

View Replies View Related

Method Is Declared To Take Three Arguments - Only Two Arguments Pass On Program Call

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

View Replies View Related

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??????

View Replies View Related

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 ...

View Replies View Related

Casting To Parameterized Types And Unchecked Warnings

Jul 15, 2014

There is a sentence in JLS 7 which I can't figure it out. It says :

A cast from a type S to a parameterized type T is unchecked unless at least one of the following conditions holds:
-S <: T
-All of the type arguments (ยง4.5.1) of T are unbounded wildcards
-T <: S and S has no subtype X other than T where the type arguments of X are not contained in the type arguments of T.

Condition one and two I got it. But the number three is really bugging me. I write some code in order to try to understand it.

class G<X>{}
class D<T,U> extends G<T>{}
G<String> g = new G<>();
D<String, Integer> dd = (D<String, Integer>) g;

In Eclipse I got no warning but it shouldn't give one ?

Because g has others subtypes than D<String, Integer> (e.g. D<String, List> , D<String, G>)

Am I missing something about the contained type arguments ?

View Replies View Related

Using Parameterized Constructor In Servlet - What Happens In Deployment Time

May 2, 2014

If i used parameterized constructor in servlet what happens in deployment time?

View Replies View Related

JSF :: Enum Type In Parametrized Class

Dec 4, 2014

I'm developing a JSF application.I have some enums, for example

public enum Gender {
MALE("Male"),
FEMALE("Female");
private final String label

[code]....

I want to put the enum value in <h:selectOneMenu>. I use a bean:

@Named(value = "genderBean")
@RequestScoped
public class GenderBean {
/**
* Creates a new instance of GenderBean
*/
public GenderBean() {

[code]...

How can i call the method .values() of enum for a generic enum T, like in the striked code?

View Replies View Related

JSP :: Add Own Class - ResultSet Cannot Be Resolved To A Type

Mar 27, 2014

I am trying to use a custom class in a .jsp page, as part of a course I am taking on Web Technologies.The original version of the jsp page was working fine, until I moved part of the Java code to a separate class.Here is the original .jsp code that is working:

<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml" lang="en-GB" xml:lang="en-GB">
<%@page pageEncoding="utf-8" %>
<head>
<meta charset="UTF-8" />
<title>Forum</title>
<link rel="stylesheet" type="text/css" href="stocktails.css" />
</head>
<body>

[code]....

View Replies View Related

How Can One Create Array Of Objects Of Class Type

Feb 10, 2015

I'm really new to object/class concepts and already having difficulties with applying them. How to create and return an array of Exam objects? I need to get a data from a textfile which is passed to the method.

Java Code:

public Exam(String firstName, String lastName, int ID, String examType, int score) {
this.firstName = firstName;
this.lastName = lastName;
this.ID = ID;
this.examType = examType;
this.score = score;

[Code] ....

View Replies View Related

How To Create Array Of Objects Of Class Type

Feb 10, 2015

I'm really new to object/class concepts and already having difficulties with applying them. how to create and return an array of Exam objects? I need to get a data from a textfile which is passed to the method.

public Exam(String firstName, String lastName, int ID, String examType, int score)

{
this.firstName = firstName;
this.lastName = lastName;
this.ID = ID;
this.examType = examType;
this.score = score;

[code]....

View Replies View Related

Private Variable With Type Of Abstract Class

Oct 10, 2014

I've got an abstract class

public abstract class AbstractClass
{
//stuff
}

And a few classes that inherit from it

public class Class1 extends AbstractClass
{
//stuff
}
public class Class2 extends AbstractClass
{
//stuff
}

within another class I have a private variable with the type of the Abstract class, and within one of the methods I assign an object to the the variable like this:

public class Test
{
private AbstractClass temp;
public testMethod(){
Class1 anObject = new Class1();
temp = anObject;
}
}

Is this legal? Will temp become a Class1 object?

View Replies View Related

How To Get Access To The Method With A Parameter Of Class Type Variable

Feb 19, 2014

how to get an access to the method with a parameter of class type variable, lets say: public void insert(Record newRecord, int pos)?

View Replies View Related







Copyrights 2005-15 www.BigResource.com, All rights reserved