Generic Types In Java

Apr 1, 2014

I am trying to understand the concept of Generics in java. In the introduction to Generic Types, this example is given:

Java Code: public class Box {
private Object object;
public void set(Object object) { this.object = object; }
public Object get() { return object; }
} mh_sh_highlight_all('java'); "Since

Since its methods accept or return an Object, you are free to pass in whatever you want, provided that it is not one of the primitive types." - I understand this.But then it has been changed to a generic class:

Java Code: /**
* Generic version of the Box class.
* @param <T> the type of the value being boxed
*/
public class Box<T> {
// T stands for "Type"
private T t;

public void set(T t) { this.t = t; }
public T get() { return t; }
} mh_sh_highlight_all('java'); "

As you can see, all occurrences of Object are replaced by T. A type variable can be any non-primitive type you specify: any class type, any interface type, any array type, or even another type variable."We can use any type in place of an Object, because Object is a superclass of all classes. But T (or any other class) is not a superclass of all classes. So how do we justify any class being used in place of a random T or any other class?

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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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Jul 11, 2014

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Here is the code:

The Class

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public String characterName;
int playerStr;
int playerCha;

[Code] ....

And the error messages:

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at TFApplet.paint(TFApplet.java:15)
at javax.swing.RepaintManager$3.run(Unknown Source)
at javax.swing.RepaintManager$3.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)

[Code] .....

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Jun 26, 2014

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..

Date firstElement = (Date)list.get(0); // Is the cast correct? Maybe. mh_sh_highlight_all('java'); so I am typing the same thing in my compiler in a small Driver class and for some reason I have an error and Im dumbfounded...

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Jun 30, 2014

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Jan 20, 2015

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[code]...

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Sep 7, 2014

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Aug 25, 2014

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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.

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private LinkedList<T> LL ;
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Feb 28, 2014

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/*
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[code]...

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Sep 9, 2014

I recently posted that JComboBox should be used in a generic manner. I presumed that once declared, with some type Foo, that one could then do:

Java Code:

JComboxBox<Foo> cb = new JComboBox<>();
// sometime later
Foo foo = cb.getSelectedItem(); mh_sh_highlight_all('java');

However, getSelectedItem() is documented to return a type of Object so a cast is still needed. I can't understand (even for backward compatibility) why it doesn't return a type of the specified type. Many other old classes have been converted to generics so why should this be any different? I just found that one could use getPrototypeDisplayValue() but that seems counter intuitive.

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Aug 5, 2014

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I wrote the following but I'm not sure how to implement or even if the concept of generics and templating can be applied to managed beans in the same way it can be applied to Dao classes:

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@EJB
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private Class<T> entityClass;

[Code] .....

The above assumes there's only one method needed in the bean. I thought of extending like this:

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Oct 3, 2014

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[code]....

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Removing 1
Size of data structure is 8
Removing 2
Size of data structure is 7

[code]....

As you can see, when I am calling the second for loop, none of the elements are being removed by my methods but the first for loop is working just fine.

Here is my code for the OrderedVector

package data_structures;
import java.util.Iterator;
import java.util.NoSuchElementException;
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[code]....

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Here is my code

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[Code].....

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[Code] .....

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Jul 21, 2014

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[Code] .....

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horoscopeEnums.java:234: error: cannot find symbol
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^
symbol: class type
location: class EnumHelper<T>
where T is a type-variable:

[Code] ....

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[Code] ....

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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;
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}
} mh_sh_highlight_all('java');

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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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[Code] .....

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