Getting Private Constructor of a Class
Hello all,
Is there any way to get the private constructor as we get the public constructors using Class.getConstructors() ?
getConstructors() method is not returning the private constructors, but I need the info about the private constructors also....so if it is possible, please let me know...
Thanks
tullio0106 wrote:
I know, however it's also impossible to invoke private methods but, using reflection, You can.That's a complete different thing. If the private method is not static, it is invoked on the current instance.
Is it also possible to use private constructors in the same way.
The problem I'm facing is to create a new instance of a class which extends another class and I need to use a private constructor of the superclass (I've no sources of that superclass).First, the Constructor of a class has to invoke a Constructor of a superclass as the first operation (either implicitely invoking an empty constructor or explicitely). There is no way to do any other operation before that. Second, a reflectively fetched Constructor instance always only can create instances of the class it is defined at (using newInstance()). So, yes, you could get access to a private Constructor. With that, you may be able to create a new instance of the class it is defined for. But that's about it.
Similar Messages
-
How to get private fields from super class?
Hi.
I must get protected and private fields from a class. I know that sounds werid but I have a very good reason for doing so, ask if you want.
I have tried the getDeclaredField(String) method, but it apparently doesn't return the fields declared by the super classes.
What's the smartest solution to this?
Thank you all.
edit: note that the superclass hierarchy's length is 3 and that there are several classes at the bottom level.
Edited by: bestam on Sep 24, 2009 2:05 PMbestam wrote:
I do not claim I have invented a new programming language Sir, you must be mistaken. This is not turing complete.
This is a language for describing Cards or a game's rules if you want.
AspectJ isn't Turing complete but AspectJ is still a compiler.
This is how I have been working :
- I have implemented the core library in Java (what is a Player, what is an Effect, what is a Card, what is a BuildingCard, what is a Player's Turn and so on)
- It also includes packages dedicated to service, able to retrieve and send data to the clients via sockets.
- Then I have "hardcoded" a dozen of specific cards in Java, for testing and validating the core library. I have been doing so by extending the BuildinCard's class for example.
- But my ultimate goal is not to code thoses 1.000+ cards of the game in Java. I chosed to design a little language so that I would end up writing cards faster. While I'm traversing the syntactical tree representing the card, I feed the card's fields one by one. Some of them are quite primitive, some other are more complex and have a recursive nature for instance.
Providing detail for how you implemented it doesn't change anything about what I already said.
Thus, this is not really a compiler as it doesn't transform a text in language A into a text in language B.
You really need to understand more about what "compilers" and certainly compiler theory do before you decide what they can and cannot do.
And your statement still does not change what I said.
Is this wrose than the bean design pattern from JSP ? I'm not sure.
Bean design? A "bean" has almost zero requirements.
Aside of that, it's a bit harsh to be told "read the fucking manual" while I have written my first compiler some years ago.Not sure who that was directed. I suggested some reading material on compiler theory.
If you think that your idea is ideal then knock yourself out. Since I doubt I will end up seeing it in anything that I must maintain it doesn't matter to me. But you did in fact ask what the best solution was. -
Private inner class with private constructor
I read that if constructor is public then you need a static method to create the object of that class.
But in the following scenario why I am able to get the object of PrivateStuff whereas it has private constructor.
I am messing with this concept.
public class Test {
public static void main(String[] args) {
Test t = new Test();
PrivateStuff p = t.new PrivateStuff();
private class PrivateStuff{
private PrivateStuff(){
System.out.println("You stuff is very private");
}A member (class, interface, field, or method) of a reference (class, interface, or array) type or a constructor of a class type is accessible only if the type is accessible and the member or constructor is declared to permit access:
* Otherwise, if the member or constructor is declared private, then access is permitted if and only if it occurs within the body of the top level class (§7.6) that encloses the declaration of the member or constructor. [Java Language Specification|http://java.sun.com/docs/books/jls/third_edition/html/names.html#6.6.1]
Your main method is within the body of the top level class, so the type (the inner class) and method are accessible.
eg:
class ImInTheSameSourceFileAsInnerAccessTest {
public static void main(String[] args) {
InnerAccessTest t = new InnerAccessTest();
InnerAccessTest.PrivateStuff p = t.new PrivateStuff();
public class InnerAccessTest {
public static void main(String[] args) {
InnerAccessTest t = new InnerAccessTest();
PrivateStuff p = t.new PrivateStuff();
private class PrivateStuff{
private PrivateStuff(){
System.out.println("You stuff is very private");
}Result:
$ javac -d bin src/InnerAccessTest.java
src/InnerAccessTest.java:4: InnerAccessTest.PrivateStuff has private access in InnerAccessTest
InnerAccessTest.PrivateStuff p = t.new PrivateStuff();
^
src/InnerAccessTest.java:4: InnerAccessTest.PrivateStuff has private access in InnerAccessTest
InnerAccessTest.PrivateStuff p = t.new PrivateStuff();
^
2 errors
Edited by: pm_kirkham on 20-Jan-2009 10:54 added example of 'in the same source file' -
Instantiate class with a private constructor
How do you call a class that happens to have a private constructor. how would one instantiate such a class? Generally constructors are supposed to be public.
But in many cases the constructor for a class can be private, so how to call such a class?khurrumnas wrote:
I dont think you would need to provide such a method (newInstance()), its there for you already in Class Class, so its suffice to just call
newInstance() to get an instance of class that happens to have a private constructor, in the simplest case.False, as jverd rightly mentioned. Example: public class Foo {
public static void main(String[] args) {
Exception expectedException = null;
try {
Bar b = (Bar) Class.forName("Bar").newInstance(); // throws Exception
} catch (Exception e) {
expectedException = e;
assert expectedException instanceof IllegalAccessException;
class Bar {
private Bar() {}
}As mentioned several times now, one can get around this restriction, but it's considered poor form to do so.
~ -
Final class and private constructor
Whats the difference in a final class and a class with private constructot?
If we can make a class non-extendable by just giving private constructor then whats the advantage of final class? (I know final is very useful for many other things but just want to get info in this contaxt)You can extend a class with a private constructor,I'm not sure about that. The compiler will complain.
KajThat depends on the signature of the private constructor.
If it's the no-arg constructor and you don't declare another constructor which you explicitly call from your derived class you will indeed get an error.
If however you never call it (and there's no way it can implicitly get called) from a derived class there should be no problem.
class Private1 {
private int q;
private Private1() {
public Private1(int i) {
q = i;
public void print() {
System.out.println(q);
public class Public1 extends Private1 {
public Public1() {
super(1);
public static void main(String[] args) {
new Public1().print();
}for example compiles and runs perfectly.
But remove the call "super(1);" from the constructor and it will fail to compile. -
Defining a Private Constructor in private section of the class?
In the exercises of ABAP OOPs book, I have the found following question.
Q. A private instance constructor (instantiation only by the class itself) can be defined in the private section.
True or False
The answer provided in the book is "True". But actually, its not possible to define a constructor in a private or protected section, regardless of the constructor visibility.
Can anyone help me in this question?from the ABAP help:
The statement METHODS constructor for the declaration of the instance constructor of a class declared with the adition CREATE PRIVATE, can not only be listed in the public, but also in the protected or private visible area. This allows the use of components, which have been declared there, in the interface of the constructor.
the problem might be your SAP system version. I have verified this on Netweaver 7.00.
best regards,
J.N.N -
Enclosing class calling private constructor of private member class
Hi all,
I have this question concerning member classes and privtae constructors.
public class MyTest {
private class Inner {
private Inner() {
System.out.println("Why Am I here!??");
public MyTest() {
Inner a = new Inner();
public static void main(String[] s) {
MyTest z = new MyTest();
}It doesn't work for my JDK SE 1.3.3, build 1.3.1-b24.
It works for many other versions.
Can somebody kindly enlighten me, should this code work?
I really didn't think that it should, but it did!I am sorry. It was actually my jikes 1.15 that was causing the problem.
After some research, I found out that my problem arose out of my understanding of OO concepts, or rather, the meaning of access modifiers in Java.
I had thought that nobody can access a private variable/method of class except the class itself. Apparently, this is not so. The access modifiers apply to the class themselves and not the object. Thus explaining why an object can access the private variables/methods of another object of the same class.
Actually, it's not really the case here. The Java language specs states that the inner class has total access to the enclosing class, but I could not find any word on enclosing class access to inner classes in the specs.
As for Jikes, I really hope they will fix it soon. I like it a lot as it is significantly faster than javac for everything I have done so far.
cheers! -
Class with private constructor can be extended or not
Hi All,
I have a doubt.
if a class has private constructor and there are some methods in this class.Can this class be extended and if yes how can we call its method in subclass?
Thanks
SumitKaranjit wrote:
If a class contains only private constructors, then it cannot be extended.Err... not the whole story!
public class Sabre20090603a
static class Fred extends Sabre20090603a
Fred()
super();
private Sabre20090603a()
} -
Why can't classes with private constructors be subclassed?
Why can't classes with private constructors be subclassed?
I know specifying a private nullary constructor means you dont want the class to be instantiated or the class is a factory or a singleton pattern. I know the workaround is to just wrap all the methods of the intended superclass, but that just seems less wizardly.
Example:
I really, really want to be able to subclass java.util.Arrays, like so:
package com.tassajara.util;
import java.util.LinkedList;
import java.util.List;
public class Arrays extends java.util.Arrays {
public static List asList(boolean[] array) {
List result = new LinkedList();
for (int i = 0; i < array.length; i++)
result.add(new Boolean(array));
return result;
public static List asList( char[] array) {
List result = new LinkedList();
for (int i = 0; i < array.length; i++)
result.add(new Character(array[i]));
return result;
public static List asList( byte[] array) {
List result = new LinkedList();
for (int i = 0; i < array.length; i++)
result.add(new Byte(array[i]));
return result;
public static List asList( short[] array) {
List result = new LinkedList();
for (int i = 0; i < array.length; i++)
result.add(new Short(array[i]));
return result;
public static List asList( int[] array) {
List result = new LinkedList();
for (int i = 0; i < array.length; i++)
result.add(new Integer(array[i]));
return result;
public static List asList( long[] array) {
List result = new LinkedList();
for (int i = 0; i < array.length; i++)
result.add(new Long(array[i]));
return result;
public static List asList( float[] array) {
List result = new LinkedList();
for (int i = 0; i < array.length; i++)
result.add(new Float(array[i]));
return result;
public static List asList( double[] array) {
List result = new LinkedList();
for (int i = 0; i < array.length; i++)
result.add(new Double(array[i]));
return result;
// Now that we extend java.util.Arrays this method is not needed.
// /**JCF already does this so just wrap their implementation
// public static List asList(Object[] array) {
// return java.util.Arrays.asList(array);
public static List asList(Object object) {
List result;
Class type = object.getClass().getComponentType();
if (type != null && type.isPrimitive()) {
if (type == Boolean.TYPE)
result = asList((boolean[])object);
else if (type == Character.TYPE)
result = asList(( char[])object);
else if (type == Byte.TYPE)
result = asList(( byte[])object);
else if (type == Short.TYPE)
result = asList(( short[])object);
else if (type == Integer.TYPE)
result = asList(( int[])object);
else if (type == Long.TYPE)
result = asList(( long[])object);
else if (type == Float.TYPE)
result = asList(( float[])object);
else if (type == Double.TYPE)
result = asList(( double[])object);
} else {
result = java.util.Arrays.asList((Object[])object);
return result;
I do not intend to instantiate com.tassajara.util.Arrays as all my methods are static just like java.util.Arrays. You can see where I started to wrap asList(Object[] o). I could continue and wrap all of java.util.Arrays methods, but thats annoying and much less elegant.Why can't classes with private constructors be
subclassed?Because the subclass can't access the superclass constructor.
I really, really want to be able to subclass
java.util.Arrays, like so:Why? It only contains static methods, so why don't you just create a separate class?
I do not intend to instantiate
com.tassajara.util.Arrays as all my methods are static
just like java.util.Arrays. You can see where I
started to wrap asList(Object[] o). I could continue
and wrap all of java.util.Arrays methods, but thats
annoying and much less elegant.There's no need to duplicate all the methods - just call them when you want to use them.
It really does sound like you're barking up the wrong tree here. I can see no good reason to want to subclass java.util.Arrays. Could you could explain why you want to do that? - perhaps you are misunderstanding static methods.
Precisely as you said, if they didn't want me to
subclass it they would have declared it final.Classes with no non-private constructors are implicitly final.
But they didn't. There has to be a way for an API
developer to indicate that a class is merely not to be
instantiated, and not both uninstantiable and
unextendable.There is - declare it abstract. Since that isn't what was done here, I would assume the writers don't want you to be able to subclass java.util.Arrays -
How to access the private constructor??
i have a one private constructor in which i define some important variables then how should i access that private constructor?(Is this related to singleton class? if possible give me some example )
Hi
you can access to your private constructor through static methods of that class.
you can create objects of that class using these static method.
example code
public class rrr
public static void main(String[] args)
a ao=a.getobj(30);
System.out.println(a.geti(ao));
class a
private int i;
private a(int x)
i=x;
static a getobj(int y)
return new a(y);
static int geti(a temp)
return temp.i;
enjoy .........
This is my first reply to forum .
If you found any problem free feel to tell
Thank you -
Private Constructors and Inheritance
Hi,
I have created a class according to the Singleton pattern, with a private constructor to prevent the public creation of class instances. Now I'd like to sub-class the Singleton, but I get errors saying the Singleton constructor is not visible. I guess this is caused by the privateness of the constructor, but I don't know if changing it to protected would ruin the Singleton pattern. Is there a good way to sub-class a Singleton?public class SingletonBase {
private static SingletonBase instance;
protected SingletonBase() throws InstantiationException {
synchronized (SingletonBase.class) {
if (instance != null)
throw new InstantiationException("single instance already exists");
else
instance = this;
public static SingletonBase getInstance() {
return instance;
} -
Why is it that AS3 does not support private constructors as AS2 does?
Why is it that AS3 does not support private constructors as
AS2 does?
Private constructors are standard in most OOP languages (for
example
C++ and Java) and were supported in Actionscript 2. However,
this is
not the case in AS3 which only allows its constructors to
have the
'public' access modifier.
I have legacy code that I hope to migrate to the AS3
platform. Some
key elements of my code rely on design patterns like the
Singleton
pattern which in turn depend on private constructors. I could
refactor
my code but, ultimately, I would lose the benefits of the
pattern
(ie. one and only one instance of the Singleton class).
I have also used private constructors to simulate enumerated
types
much like the enums you would find in Java 5 and up. But I
can't
use the same implementation in AS3 without private
constructors.
I do not want to resort to mixing legacy code with new AS3
code to
keep functionality intact. Are there any possible
work-arounds for
this issue?
If not, are there any lobbying groups I need to know about so
that
we can get this feature back?http://www.gskinner.com/blog/archives/2006/07/as3_singletons.html
-
Problem with constructor of inner class.
Hi everybody!
I have an applet which loads images from a database.
i want to draw the images in a textarea, so i wrote an inner class, which extends textarea and overrides the paint method.
but everytime i try to disply the applet in the browser this happens:
java.lang.NoClassDefFoundError: WohnungSuchenApplet$Malfl�che
at java.lang.Class.getDeclaredConstructors0(Native Method)
at java.lang.Class.privateGetDeclaredConstructors(Class.java:1590)
at java.lang.Class.getConstructor0(Class.java:1762)
at java.lang.Class.newInstance0(Class.java:276)
at java.lang.Class.newInstance(Class.java:259)
at sun.applet.AppletPanel.createApplet(AppletPanel.java:567)
at sun.plugin.AppletViewer.createApplet(AppletViewer.java:1778)
at sun.applet.AppletPanel.runLoader(AppletPanel.java:496)
at sun.applet.AppletPanel.run(AppletPanel.java:293)
at java.lang.Thread.run(Thread.java:536)
so my class has no own constructor, it just has the paint method overwritten.
my class looks like this:
public class Malfl�che extends javax.swing.JTextArea{
public void paint(Graphics g){
Color grey=new Color(220,220,220);
g.drawImage(img,10,10,null);
how should a constructor for this class look like?
sorry i am quite new to this, so i really dont have a clue!
my class does not have any attributes or requires any so it doesnt need a constructor, doesnt it?
thanks a lot
timFirst off, unlike regular classes, inner classes can be declared public, private, protected, and default.
Secondly, why are you using the JTextArea to display an image, why not use a JLabel, which takes an Image object as its constructor.
Thirdly, when you drew your image you did not give it a width and height
g.drawImage(img, 0,0, img.getWidth(null), img.getHeight(null), null);
otherwise it will make your image 1 X 1 pixels. not big enough to see. -
Error with instance variable and constructor of base class
I am getting the error on the following statement "protected Point apoint" of by base class. What is causing this problem? See my code:
package Shapes;
public abstract class Shapes
protected Point apoint; / ****error at this line****/
public void move(double xdelta, double ydelta)
apoint.x += xdelta;
apoint.y += ydelta;
public abstract void distance();
public abstract void show();
public String toString()
return "\nThe starting point is at coordinates ("+x+","+y+")";
package Shapes;
public class Lines extends Shapes
protected Point start;
protected Point end;
protected double x;
protected double y;
double delta;
public Lines( final Point apoint, final Point bpoint)
start.x = apoint.x;
start.y = apoint.y;
end.x = bpoint.x;
end.y = bpoint.y;
public Lines(double xstart, double ystart, double xend, double yend)
this.xstart = xstart;
this.ystart = ystart;
this.xend = xend;
this.yend = yend;
public Lines(double x, double y)
this.x = x;
this.y = y;
public void distance(final Lines start, final Lines end)
delta = abs(Math.sqrt (super.x - start.x) * (super.x - end.x) +
(super.y - start.y) * (super.y - end.y));
Lines move(Point start, double delta)
end.x += delta;
end.y += delta;
return new Point(end);
public Lines show()
g.drawLine( start.x, start.y, end.x, end.y);
public String toString()
return super.toString()+ "\n moved distance is("
+ start + ") : (" + end + ")"
+" \n to position(" + start + " ) : (" + end + ")";
package Shapes;
public class Rectangle extends Lines
double delta;
public Rectangle (Point top_lft_pt, Point bottom_rght_pt)
super(top_lft_pt, bottom_rght_pt);
public Rectangle(double x_top_lft, double y_top_lft, double x_bottom_rght, double y_bottom_rght)
super(x_top_lft, y_top_lft, x_bottom_rght, y_bottom_rght);
public Rectantgle is_it_diagonal()
if(top_lft.x > bottom_rght.x && bottom_rght.x < top_lft.x)
System.out.println("Point are Not Diagonal");
public void distance(double delta)
delta = abs(Math.sqrt (top_lft.x - bottom_rght.x) * (top_lft.x - botton_rght.x) +
(top_lft.y - bottom_rght.y) * (top_lft.y - bottom_rght.y));
public Rectangle move(final Point top_lft_pt, double delta)
bottom_rght.x += delta;
bottom_rght.y += delta;
return new Point(bottom_rght_pt);
public void get_top_rght_coords()
Point top_rght = new Point();
top_rght.x = bottom_rght.x;
top_rght.y = top_lft.y;
public void get_bottom_left_coords()
Point bottom_lft = new Point();
bottom_lft.x = top_lft.x;
bottom_lft.y = bottom_rght.y;
public Rectangle show()
g.drawLine(top_lft.x, top_lft.y, top_rght_x, top_rght_y);
g.drawLine(bottom_lft.x, bottom_lft.y, bottom_rght.x, bottom_rght.y);
g.drawLine(top_lft.x, top_lft.y, bottom_lft.x, bottom_lft.y);
g.drawLine(top_rght.x, top_rght.y, bottom_rght.x, bottom_rght.y);
package Shapes;
public class Circles extends Lines
protected double radius;
public double delta;
protected Point center;
public Circles(double x, double y, double radians)
super(x, y);
radius = radians;
public Circles(Point acenter)
center.x = acenter.x;
center.y = acenter.y;
public void distance()
delta = abs(Math.sqrt(super.x - x) * (super.x - x) + (super.y - y) * (super.y -y));
public Circles move(final Point Circles, double delta)
return new Point(Circles);
public void show()
g.drawOval(Circles.x, Circles.y, radius, radius);
package Shapes;
import java .math .*;
import java.util .Random ;
public class ShapesDriver
Shapes[] aShape = new Shapes[10];
static double range = 101.0;
static Random r1 = new Random();
public static void main(String [] args)
double[][] coords = new double[10][10];
double[] radians = new double [10];
Shapes anyShape = {
new Circles(radians),
new Lines(coords),
new Rectangle(coords)
Shapes aShape; /***error at this line***/
for(int i = 1; i <= coords.length; i++)
for(int j = 1; j <= coords.length; j++)
coords[i][j] = r1.nextDouble () * range;
radians[j] = r1.nextDouble () * range;
aShape[i] = anyShape[r1.nextInt(aShape.length)];
System.exit(1);Thanks for your help with this problem. Now I have another problem that I am having a hard time figuring out. My program is using inheritance and polymorphism. I trying to use only one version of methods in the superclass points which extends the shapes class which is the abstract superclass vs. repeating the implementation of the methods (move, show, etc.) in each of the subclasses. The error I am getting is this "declare the class abstract, or implement abstract member 'Point Shapes.move()'. As you see, move is declared abstract and of type point in the Shapes superclass and it's behavior is implemented in the subclass Points extending Shapes. The other subclasses, circle, rectangle and lines will invoke the move method from Points and return a new point object. Why I am I getting the error to declare or implement move when the implementation is in Point?
Below is code, please help?
import java .awt .Point ;
public class ShapesDriver
public static void main(String args[])
int count = 0;
int choice;
Point start = null;
Point end = null;
System.out .println(" 1 i am here");
start = new Point((int)(Math.random()* 10.0), (int)(Math.random()* 10.0));
end = new Point((int)(Math.random()* 10.0), (int)(Math.random()* 10.0));
System.out .println(" 2 i am here");
System.out.println (start);
System.out.println(end);
for(int i = 0; i <= count; i++)
System.out .println(" 3 i am here");
choice = (int)(4.0 * Math.random());
System.out .println(" 4 i am here");
System.out.println (choice);
switch(choice)
case 0: //Lines
System.out .println(" 5 i am here");
Lines apoint = new Lines((int)(Math.random()* 10.0), (int)(Math.random()* 10.0),
(int)(Math.random()* 10.0), (int)(Math.random()* 10.0));
Point coords = new Point((int)(Math.random()* 10.0),
(int)(Math.random()* 10.0));
new Point((int)(Math.random()* 10.0),
(int)(Math.random()* 10.0));
break;
case 1: //Circles
System.out .println(" 6 i am here");
Circles center = new Circles((double)(Math.random()* 10.0),
(double)(Math.random()* 10.0), (double)(Math.random()* 10.0),
(double)(Math.random()* 10.0),(double)(Math.random()* 10.0));
Circles centerpt = new Circles((int)(Math.random()* 10.0),
(int)(Math.random()* 10.0), (int)(Math.random()* 10.0),
(int)(Math.random()* 10.0), (double)(Math.random()* 10.0));
break;
case 2: //Rectangles
System.out .println(" 7 i am here");
Rectangle top_lft_pt = new Rectangle ((double)(Math.random()* 10.0),
(double)(Math.random()* 10.0), (double)(Math.random()* 10.0),
(double)(Math.random()* 10.0), (double)(Math.random()* 10.0),
(double)(Math.random()* 10.0));
Rectangle bottom_rgt_pt = new Rectangle ((double)(Math.random()* 10.0),
(double)(Math.random()* 10.0), (int)(Math.random()* 10.0),
(int)(Math.random()* 10.0), (int)(Math.random()* 10.0),
(int)(Math.random()* 10.0));
break;
default:
System.out .println(" 9 i am here");
System.out.println("\nInvalid shape choice =" + choice);
System.exit(0);
break;
try
System.in.read();
catch(java.io.IOException ioe)
import java .awt .Point ;
public abstract class Shapes
private String shape;
public Shapes(String ashape)
shape = new String(ashape);
public abstract Point move();
public double distance()
return 0.0;
public abstract void show();
public String toString()
return "\nThis shape is a" + shape;
import java .awt .Point ;
public class Rectangle extends Points
protected Point top_lft;
protected Point top_rgt;
protected Point bottom_lft;
protected double top_lft_x;
protected double top_lft_y;
protected double bottom_rgt_x;
protected double bottom_rgt_y;
protected Point bottom_rgt;
protected double delta = 0;
protected String shape = "Rectangle";
public Rectangle(double x, double y, double top_lft_x,
double top_lft_y, double bottom_rgt_x,
double bottom_rgt_y)
super(x, y);
top_lft_x = top_lft_x;
top_lft_y = top_lft_y;
bottom_rgt_x = bottom_rgt_x;
bottom_rgt_y = bottom_rgt_y;
public Rectangle( double x, double y, Point bottom_rgt, Point top_lft)
super(x, y);
bottom_rgt_x = bottom_rgt.x;
bottom_rgt_y = bottom_rgt.y;
top_lft_x = top_lft.x;
top_lft_y = top_lft.y;
public String toString()
return super.toString() + " coordinates top left= " + top_lft_x + "," + top_lft_y + "and bottom right" +
bottom_rgt_x + "," + bottom_rgt_y + ")";
public void is_it_diagonal()
if(top_lft_x < bottom_rgt_x && bottom_rgt_x > top_lft_x)
System.out.println("Points are Not Diagonal");
public double distance()
distance ();
return delta;
public Point move(Point top_lft)
move();
bottom_rgt_x += delta;
bottom_rgt_y += delta;
return top_lft;
public void get_other_coords()
top_rgt.x = bottom_rgt.x;
top_rgt.y = top_lft.y;
bottom_lft.x = top_lft.x;
bottom_lft.y = bottom_rgt.y;
public void show()
super.show();
System.out.println("new coords are :");
System.out .println ("(" + top_lft_x + "," + top_lft_y + ")");
System.out .println ("top right(" + top_rgt + ")");
System.out .println ("(" + bottom_rgt_x + "," + bottom_rgt_y + ")");
System.out .println ("bottom right(" + bottom_rgt + ")");
import java .awt .Point ;
public class Points extends Shapes
protected double delta = 0.0;
protected double x;
protected double y;
protected String ashape = "Points";
public Points( double x, double y)
super("Points");
x = x;
y = y;
public Points( Point start)
super("Points");
x = start.x;
y = start.y;
public String toString()
return super.toString() + "References coordinates(" + x + y + ")";
public double distance(double x1, double y1 )
return delta =(Math.sqrt(x - x1) * (x - x1) + (y - y1) *
(y - y1));
public Point move(Point pts)
pts.x += delta;
pts.y += delta;
return pts;
public void show()
System.out.println("This shape is a" + ashape + "(" +
"(" + x+ "," + y + ")");
import java .awt .Point ;
public class Lines extends Points
double delta = 0;
protected double x;
protected double y;
protected String ashape = "Lines";
public Lines( double x1, double y1, double x, double y)
super(x1,y1);
x = x;
y = y;
public Lines(Point start, Point end)
super(start);
x = end.x;
y = end.y;
public String toString(Point end)
return super.toString() + "line points = (" + x + "," + y +
"(" + end + ")";
public double distance()
distance ();
return delta;
public Point move(Point lines)
move ();
return lines;
public void show()
System.out.println("This shape is a" + ashape + "(" +
"(" + x + "," + y + ")");
import java .awt .Point ;
public class Circles extends Points
protected double radius;
protected double xcenter;
protected double ycenter;
protected String ashape = "Circle";
public Circles( double x, double y, double cx, double cy, double radians)
super(x, y);
xcenter = cx;
ycenter = cy;
radius = radians;
public Circles( Point acenter, Point ref, double radians)
super(ref);
xcenter = acenter.x;
ycenter = acenter.y;
radius = radians;
public String toString(Point ref)
return super.toString() + " reference points (" +
ref + ")" +
"center coordinates (" + xcenter + "," + ycenter + ")";
public double distance(Point ref)
return (Math.sqrt(ref.x - xcenter) * (ref.x - xcenter)
+ (ref.y - ycenter) *
(ref.y - ycenter));
public Point move(Point center)
move();
return center;
public void show()
System.out.println("This shape is a" + ashape + "(" +
"(" + xcenter + "," + ycenter + ")"); -
How to get the name of a class invoking
Can a method get the name of the class invoking it?
As:
public void myMethod(){
System.out.println("the name of the class invoking this method is: " + XXXXX);
}Edited by: Maria1990 on Aug 17, 2010 8:46 AMMaria1990 wrote:
.getStackTrace() gives me an array with the all details.Or, if you only care about the class, ask a SecurityManager.
public final class ClassUtils {
public static final Class[] getClassContext() {
return new SecurityManager() {
protected Class[] getClassContext(){return super.getClassContext();}
}.getClassContext();
private ClassUtils() {};
public static final Class getCallingClass() { return getClassContext()[2];}
}
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