It&#39;ll have abstract as one of its modifiers when you call getModifiers() on the class object.

This [link][1] should help.

     Modifier.isAbstract( someClass.getModifiers() );

Also:


[http://java.sun.com/javase/6/docs/api/java/lang/reflect/Modifier.html][2]

[http://java.sun.com/javase/6/docs/api/java/lang/Class.html#getModifiers()][3]


  [1]: http://java.sun.com/docs/books/tutorial/reflect/class/classModifiers.html &quot;link&quot;
  [2]: http://java.sun.com/javase/6/docs/api/java/lang/reflect/Modifier.html
  [3]: http://java.sun.com/javase/6/docs/api/java/lang/Class.html#getModifiers()

    Class myClass = myJar.load(&quot;classname&quot;);
    bool test = Modifier.isAbstract(myClass.getModifiers());


    public static boolean isInstantiable(Class&lt;?&gt; clz) {
		if(clz.isPrimitive() || Modifier.isAbstract( clz.getModifiers()) ||clz.isInterface()  || clz.isArray() || String.class.getName().equals(clz.getName()) || Integer.class.getName().equals(clz.getName())){
			return false;
		}
		return true;
	}

I&#39;m after some simple examples and best practices of how to use regular expressions in ANSI C. `man regex.h` does not provide that much help.

Regular expressions in C: examples?

`UIView` has the properties `frame`, `bounds`, `center`, and `origin`, and they all seem to be interrelated.  Most of the time, I deal with `frame` when setting the position and size of a `UIView`.  I understand that `frame` is using global coordinate system and `bounds` is using coordinate of the local view (therefore its x and y are 0, but not always), but it&#39;s still confusing to me when to use what.

Under what context (and what&#39;s the right time) the other properties (`bounds`, `center`, `origin`) should be used?


UIView&#39;s frame, bounds, center, origin, when to use what?

I am interating through classes in a Jar file and wish to find those which are not abstract. I can solve this by instantiating the classes and trapping InstantiationException but that has a performance hit as some classes have heavy startup. I can&#39;t find anything obviously like isAbstract() in the Class.java docs.


How can I determine whether a Java class is abstract by reflection

<p>I am interating through classes in a Jar file and wish to find those which are not abstract. I can solve this by instantiating the classes and trapping InstantiationException but that has a performance hit as some classes have heavy startup. I can't find anything obviously like isAbstract() in the Class.java docs.</p>


This may be something common and trivial, but I seem to be having trouble finding a concrete answer. In C# there is a concept of delegates, which relates strongly to the idea of function pointers from C++. Is there a similar functionality in Java? Given that pointers are somewhat absent, what is the best way about this? And to be clear, we&#39;re talking first class here.

Function Pointers in Java

how I can rewrite this:

    for (int i = 0; i &lt; numberOfSpaces; i++) {
        System.out.print(&quot; &quot;);
    }

using `String.format()`?


*PS*

I&#39;m pretty sure that this is possible but the [javadoc is a bit confusing][1].


  [1]: http://java.sun.com/javase/6/docs/api/java/util/Formatter.html#syntax

print spaces with String.format()

How do I convert `int[]` into `List&lt;Integer&gt;` in Java?

Of course, I&#39;m interested in any other answer than doing it in a loop, item by item. But if there&#39;s no other answer, I&#39;ll pick that one as the best to show the fact that this functionality is not part of Java.

How to convert int[] into List&lt;Integer&gt; in Java?

I have two user Objects and while I try to save the object using 

    session.save(userObj);

I am getting the following error:

    Caused by: org.hibernate.NonUniqueObjectException: a different object with the same identifier value was already associated with the session:
    [com.pojo.rtrequests.User#com.pojo.rtrequests.User@d079b40b]

I am creating the session using 

    BaseHibernateDAO dao = new BaseHibernateDAO(); 			

    rtsession = dao.getSession(userData.getRegion(),
                               BaseHibernateDAO.RTREQUESTS_DATABASE_NAME);

    rttrans = rtsession.beginTransaction();
    rttrans.begin();
    
    rtsession.save(userObj1);
    rtsession.save(userObj2);
    
    rtsession.flush();
    rttrans.commit();
    
    rtsession.close(); // in finally block

I also tried doing the `session.clear()` before saving, still no luck.

This is for the first I am getting the session object when a user request comes, so I am getting why is saying that object is present in session.

Any suggestions?


Hibernate Error: org.hibernate.NonUniqueObjectException: a different object with the same identifier value was already associated with the session

I want to add the oracle jdbc driver to my project as dependency (runtime scope) - ojdbc14.
In MVNrepository site the dependency to put in the POM is:

&lt;!-- language: xml --&gt;

    &lt;dependency&gt;
        &lt;groupId&gt;com.oracle&lt;/groupId&gt;
        &lt;artifactId&gt;ojdbc14&lt;/artifactId&gt;
        &lt;version&gt;10.2.0.3.0&lt;/version&gt;
    &lt;/dependency&gt;

of course this does&#39;t work as it is not in the central repository used by maven.
2 questions:

1. How do I find a repository (if any) that contains this artifact?

2. How do I add it so that Maven will use it?

Find Oracle JDBC driver in Maven repository

I am writing a custom wrapper for `open_flash_chart` plugin. It&#39;s placed in `/lib` and load it as a module in `ApplicationController`.

However, I have some Class hierarchy or smth problem.

From any controller I can access `open_flash_chart` functions as `OpenFlashChart`, `Line` etc

However, in a class in a `/lib` module, it doesnt work!

Any ideas?

Rails /lib modules and

&gt; **Possible Duplicate:**  
&gt; [How many Python classes should I put in one file?](https://stackoverflow.com/questions/106896/how-many-python-classes-should-i-put-in-one-file)  


Coming from a C++ background I&#39;ve grown accustomed to organizing my classes such that, for the most part, there&#39;s a 1:1 ratio between classes and files.  By making it so that a single file contains a single class I find the code more navigable.  As I introduce myself to Python I&#39;m finding lots of examples where a single file contains multiple classes.  Is that the recommended way of doing things in Python?  If so, why?

Am I missing this convention in the [PEP8][1]?


  [1]: http://www.python.org/dev/peps/pep-0008/

Are multiple classes in a single file recommended?

The question is best explained by an example:

In Java for a JPA EntityManager, I can do the following(Account is my Entity class):

    Account result = manager.find(Account.class, primaryKey);

In Scala, my naive attempt is:

    val result = manager.find(Account.class, primaryKey)

But when I try to use `Account.class` in Scala, it seems to not like this.  How can I specify the java.lang.Class&lt;Account&gt; object for the Account class in Scala?



Scala equivalent of Java java.lang.Class&lt;T&gt; Object

We&#39;re often told we should protect encapsulation by making getter and setter methods (properties in C#) for class fields, instead of exposing the fields to the outside world.

But there are many times when a field is just there to hold a value and doesn&#39;t require any computation to get or set. For these we would all do this number:

    public class Book
    {
        private string _title;
    
        public string Title
        {
              get =&gt; _title; 
              set =&gt; _title = value;
        }
    }

Well, I have a confession, I couldn&#39;t bear writing all that (really, it wasn&#39;t having to write it, it was having to look at it), so I went rogue and used public fields.

Then along comes C# 3.0 and I see they added automatic properties:

    public class Book
    {
        public string Title { get; set; } 
    }

Which is tidier, and I&#39;m thankful for it, but really, what&#39;s so different than just making a public field?

    public class Book
    {
        public string Title;
    }

 


Public Fields versus Automatic Properties

PHP is my first programming language. I can&#39;t quite wrap my head around when to use static classes vs instantiated objects.

I realize that you can duplicate and clone objects. However in all of my time using php any object or function always ended up as a single return (array, string, int) value or void.

I understand concepts in books like a video game character class. *duplicate car object and make the new one red*, that all makes sense, but what doesn&#39;t is its application in php and web apps.

A simple example. A blog. What objects of a blog would be best implemented as static or instantiated objects? The DB class? Why not just instantiate the db object in the global scope? Why not make every object static instead? What about performance?

Is it all just style? Is there a proper way to do this stuff?

When to use static vs instantiated classes

Why can&#39;t Java classes have abstract fields like they can with abstract methods?

For example: I have two classes that extend the same abstract base class.  These two classes each have a method that is identical except for a String constant, which happens to be an error message, within them. If fields could be abstract, I could make this constant abstract and pull the method up into the base class. Instead, I have to create an abstract method, called `getErrMsg()` in this case, that returns the String, override this method in the two derived classes, and then I can pull up the method (which now calls the abstract method).

Why couldn&#39;t I just make the field abstract to begin with? Could Java have been designed to allow this?

Why not abstract fields?

I am coming from c# where this was easy, and possible.

I have this code:

    public abstract class clsAbstractTable {
    	
    	public abstract String TAG;
        public abstract void init();
    
    }

but Eclipse tells me I use illegal modifier. 

I have this class:

    public class clsContactGroups extends clsAbstractTable {
    
    	
    }

I want the variable and method defined in such way, that Eclipse to **prompt me**, I have unimplemented abstract **variables** and methods.

How do I need to define my abstract class so I should be prompted to implement the abstracts?

**EDIT 1**

I will create different classes for different db tables. Each class should have it&#39;s own TABLENAME variable, no exception. I have to make sure this variable is static each time when I create a new class that extends the abstract class.

Then in the abstract class I will have a method eg: init();

If in this init() method I call TABLENAME, it should take the value from the sub-class.

something like this should also work out

    String tablename=(clsAbstract)objItem.TABLENAME;
    // where objItem can be any class that extended clsAbstract;

**EDIT 2**

I want a constant(static) defined in each class having it&#39;s name defined in abstract. 

 - I define variable TABLENAME in abstract, but no value given.
 - I create a clsContactGroups, I should be prompted to implement TABLENAME, this is where gets some data. eg: TABLENAME=&quot;contactgroups&quot;;
 - I create a second class clsContacts, I should be prompted to implement TABLENAME, this is where gets some data. eg: TABLENAME=&quot;contacts&quot;;  
etc...

Abstract variables in Java?

I&#39;ve set up an abstract parent class, and a concrete class which extends it. Why can the parent class not call the abstract function?

    //foo.php
    &lt;?php
        abstract class AbstractFoo{
            abstract public static function foo();
            public static function getFoo(){
                return self::foo();//line 5
            }
        }
        
        class ConcreteFoo extends AbstractFoo{
            public static function foo(){
                return &quot;bar&quot;;
            }
        }
        
        echo ConcreteFoo::getFoo();
    ?&gt;

Error: 

&gt; Fatal error: Cannot call abstract method AbstractFoo::foo() in **foo.php**  on line 5

Why can&#39;t you call abstract functions from abstract classes in PHP?

What is the difference between `sealed abstract` and `abstract` Scala class?

Scala&#39;s sealed abstract vs abstract class

I have an abstract class A that define abstract methods. This means that, for a class to be instanciable, all the abstract method have to be implemented.

I&#39;d like all my subclasses to implement a constructor with 2 ints as parameters. 

Declaring a constructor defeats my purpose, as I want the constructor defined in subclasses and I don&#39;t know anything about the implementation. Moreover I cannot declare a constructor as being abstract;

Is there a way to do this ?

__Example of what I want:__

Lets say that I am defining the API of a Matrix class. In my problem, Matrix cannot change their dimensions.

For a Matrix to be created, I need to provide its size.

Hence, I want all my implementors to provide the constructor with the size as a parameter. This constructor is motivated by the problem, not by an implementation concern. The implementation can do whatever it wants with these, provided that all the semantic of the methods are kept.

Let&#39;s say I want to provide a basic implementation of the `invert()` method in my abstract class. This method will create a new matrix with `this` inverted dimensions. More specifically, as it is defined in the abstract class, it will create a new instance of the same class as `this`, using a constructor that takes two ints. As it does not know the instance it will use reflection (getDefinedConstructor) and I want a way to waranty that I&#39;ll get it and that it will be meaningfull for the implementation.


Content Type	Original Author	Original Content on Stackoverflow
Question	peter.murray.rust	View Question on Stackoverflow
Solution 1 - Java	seth	View Answer on Stackoverflow
Solution 2 - Java	Stobor	View Answer on Stackoverflow
Solution 3 - Java	Abdushkur Ablimit	View Answer on Stackoverflow

How can I determine whether a Java class is abstract by reflection

Java Problem Overview

Java Solutions

Solution 1 - Java

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Solution 3 - Java

UIView's frame, bounds, center, origin, when to use what?

Regular expressions in C: examples?

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