Constructors in Junit classes?

I need to create a few test of how a class Exporter works. Since setting up Exporter takes some time I have placed it in the Constructor of the below Junit test class:
public class CreateDataTest {
     private Exporter exporter;
     public CreateDataTest() {
          exporter = new Exporter();
          exporter.setup();
     @Test
     public void dataType0() throws Exception {
                boolean res = exporter.create("type0");
          assertEquals(res, true);
     @Test
     public void dataType1() throws Exception {
                boolean res = exporter.create("type1");
          assertEquals(res, true);
}The first test runs fine, but the nexts test throws an exception (not because of the assertEquals call) :
java.lang.ExceptionInInitializerError
I don't want to put
exporter = new Exporter();
exporter.setup();
In a @Before method since it wil be create each time a new test is run.
Is there some way to generate "permanent" data for a Junit test that is created only once and not use @Before?

fedevaps wrote:
Ok and all variables in a static methods must also be static right?Of course. You can't access non-static members directly in a static method.

Similar Messages

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
tim

First 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.

Why could the "this" be used in the constructor of a class?

We often see this kind of code below:
public class myClass1 {
private List list;
public myClass1(String aStr){
this.list = new List(12, false); // The "this" is what confuses me.
The code above seems nature. But the question is that the "this" means "the instance of the current class", and we say that the instance of a class initiates after the constructor of the class is invoked.
How could it happen that the JVM knows "this" before it class is initiated ?

I have found that this convention very helpful, especially when you remember that you're using the new operator:class MyClass
int x;
int y;
public MyClass ( int newx, newy )
    x = newx;
    y = newy;
void setPos ( int newx, newy )
    x = newx;
    y = newy;
}This avoids the unnecessary use of this
Doug

NewInstance & constructor of base class

When I instantiate a sub class directly (using new), the code in the constructor method of both base and sub classes run.
When I instantiate using java.lang.reflect.Constructor.newInstance, only the sub class's constructor method is invoked. Is there a way to force running the constructor method of the base class as well?
Thanks & Regards.

when I tried to build a simple code to show the problem, I realised that the problem is somewhere else - Still not solvable by me - Please help.
Irrespective of whether new or Constructor.newInstance -
The constructor method with appropriate signature is invoked from child class.
The constructor method without any arguments is invoked from parent class. - This is the reason for my original problem.
In the attached code, the variable xyz is not getting assigned proper value (from the argument a).
public class Mainer {
   public static void main(String args[]) throws ClassNotFoundException, NoSuchMethodException, InstantiationException, IllegalAccessException, IllegalArgumentException, java.lang.reflect.InvocationTargetException
       int inArg = 5;
       System.out.println("With new");
       ChldClass chld1 = new ChldClass(inArg);
       chld1.m1();
       System.out.println("With Constructor.newInstance");
       java.lang.reflect.Constructor ArgsConstructor;
       Class[] argsClass = new Class[] {int.class};
       Class chld2Class = Class.forName("ChldClass");
       ArgsConstructor = chld2Class.getConstructor(argsClass);
       Object[] argsObject = new Object[] {5};
       ChldClass chld2 = (ChldClass)ArgsConstructor.newInstance(argsObject);
       chld2.m1();
class PrntClass
    int xyz;
        public PrntClass(int a)
            xyz = a;
            System.out.println("Int Arg Constructor within Parent Class <<<" + xyz + ">>>");
        public PrntClass()
            System.out.println("Default Constructor within Parent Class");
     public void m1()
          System.out.println("M1 of Parent Class");
class ChldClass extends PrntClass
    public ChldClass(int a)
        System.out.println("Int Arg Constructor within Child");
     public void m1()
          System.out.println("Value of xyz "+xyz);
     public void m2()
          System.out.println("M2 of ChldClass");
The result displayed:
With new
Default Constructor within Parent Class
Int Arg Constructor within Child
Value of xyz 0
With Constructor.newInstance
Default Constructor within Parent Class
Int Arg Constructor within Child
Value of xyz 0
Thanks & Regards.

Use of constructor in abs class?

What is the use of writing constructors in abstract class?

You would use an abstract class's constructor to initialize the state of an object of that class, just the same as any other class.

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.

Calling constructor of super class

Hello everyone! I'm a student. I hope I can find guidance. Here's the issue:
Super class: Property
Sub class: House
constructor of parent class:
protected Property(String id, char status, String address,
        String tenet, String landlord, long rent, char freq,
        long amtDue, String date, boolean repair, char tradesman)
        this.id = id;
        this.status = status;
        this.address = address;
        this.tenet = tenet;
        this.landlord = landlord;
        this.rent = rent;
        this.freq = freq;
        this.amtDue = amtDue;
        this.repair = repair;
        this.tradesman = tradesman;
        SimpleDateFormat formatter = new SimpleDateFormat("dd.MM.yy");
        this.dateDue = formatter.parse(date, new ParsePosition(0));
    }the constuctor of the sub class:
public House(String id, char status, String address,
        String tenet, String landlord, long rent, char freq,
        long amtDue, String dateDue, boolean repair, char tradesman,
        int broom, int proom, int throom, boolean garden,
        boolean garage, boolean heating)
    super(id, status, address, tenet, landlord, rent, freq,
        amtDue, dateDue, repair, tradesman);
    this.broom = broom;
    this.proom = proom;
    this.throom = throom;
    this.garden = garden;
    this.garage = garage;
    this.heating = heating;
    }I'm sure you notice I'm calling the constructor of the Property in House. That;s where the error is when i try to compile either class. This is the error it shows within the House class.
Object() in java.lang.Object cannot be applied to (java.lang.String,char,java.lang.String,java.lang.String,java.lang.String,long,char,long,java.lang.String,boolean,char)
Maybe its elementary? Thanks in advance..

You haven't pasted all the code so I can only guess that the class House does not extend Property class.
public class House extends Property
// put the constructor here
}If the House class does not extend Property (or any other class) it just extends (by default) the Object class, which does not have the constructor of Property class.
Hope it helps
Nick

Constructor of derived-class has to call constructor of super-class?

In java, constructor of derived-class has to call constructor of super-class? there is no way to omit this step?

Correct. If you do not explicitly call the constructor, a call to the no-arg c'tor, super(), is automatically inserted.
It would be a mess to have it any other way. You'd be creating objects that are not completely initialized. They'd be in an invalid state.
Constructor rules:
1) Every class has at least one ctor.
1.1) If you do not define an explicit constructor for your class, the compiler provides a implicit constructor that takes no args and simply calls super().
1.2) If you do define one or more explicit constructors, regardless of whether they take args, then the compiler no longer provides the implicit no-arg ctor. In this case, you must explicitly define a public MyClass() {...} if you want one.
1.3) Constructors are not inherited.
2) The first statement in the body of any ctor is either a call to a superclass ctor super(...) or a call to another ctor of this class this(...) 2.1) If you do not explicitly put a call to super(...) or this(...) as the first statement in a ctor that you define, then the compiler implicitly inserts a call to super's no-arg ctor super() as the first call. The implicitly called ctor is always super's no-arg ctor, regardless of whether the currently running ctor takes args.
2.2) There is always exactly one call to either super(...) or this(...) in each constructor, and it is always the first call. You can't put in more than one, and if you put one in, the compiler's implicitly provided one is removed.

Can defualt inherited the Super Class constructor to sub class ?

Hi,
is it passible to inherit the super class constructor by defualt when extends the super class.
Thanks
MerlinRoshina

Constructor rules:
1) Every class has at least one ctor.
1.1) If you do not define an explicit constructor for your class, the compiler provides a implicit constructor that takes no args and simply calls super().
1.2) If you do define one or more explicit constructors, regardless of whether they take args, then the compiler no longer provides the implicit no-arg ctor. In this case, you must explicitly define a public MyClass() {...} if you want one.
1.3) Constructors are not inherited.
2) The first statement in the body of any ctor is either a call to a superclass ctor super(...) or a call to another ctor of this class this(...) 2.1) If you do not explicitly put a call to super(...) or this(...) as the first statement in a ctor that you define, then the compiler implicitly inserts a call to super's no-arg ctor super() as the first call. The implicitly called ctor is always super's no-arg ctor, regardless of whether the currently running ctor takes args.
2.2) There is always exactly one call to either super(...) or this(...) in each constructor, and it is always the first call. You can't put in more than one, and if you put one in, the compiler's implicitly provided one is removed.

Constructor accepting another class object

I have two classes. One is Address class and other is AddressBookEntry class
I havebeen asked to code a constructor in AddressBookEntry class that accepts name and the Address object. Can anyone tell what I've coded is correct or not(last part of the code)?
public class Address{
     private String street;
     private String city;
     private String state;
     private String zipcode;
     public Address(String addressStreet, String addressCity,
          String addressState, String addressZipcode){
          street = addressStreet;
          city = addressCity;
          state = addressState;
          zipcode = addressZipcode;
     } // end constructor
     public String getStreet(){ return street;}
     public String getCity(){ return city;}
     public String getState(){ return state;}
     public String getZipcode(){ return zipcode;}
     public String toString() {
     String addressObject = street+ "," + city + "," + state + "," +zipcode;
     return addressObject;
public class AddressBookEntry{
     private String name;
     private Address address;
     public static int entriesCount = 0;
     public AddressBookEntry(String entryName,Address addressObject){
          name = bookEntryName; // constructor in the AddessBookEntry class
          address = addressObject;

Still I have pblm with my assignment. I have modified my code
Address class
public class Address{
     private String street;
     private String city;
     private String state;
     private String zipcode;
     public Address(String addressStreet, String addressCity,
          String addressState, String addressZipcode){
          street = addressStreet;
          city = addressCity;
          state = addressState;
          zipcode = addressZipcode;
     } // end constructor
     public String getStreet(){ return street;}
     public String getCity(){ return city;}
     public String getState(){ return state;}
     public String getZipcode(){ return zipcode;}
     public String toString() {
     String addressObject = street+ "," + city + "," + state + "," +zipcode;
     return addressObject;
}b]AddressBookEntry
public class AddressBookEntry{
     private String name;
     private Address address;
     public static int entriesCount = 0;
     public AddressBookEntry(String entryName,Address addressObject){
          name = entryName;
          address = addressObject;
     public AddressBookEntry(String entryName, String entryStreet,     String entryCity,
                                   String entryState, String entryZipcode){
          name = entryName;
          address.street = entryStreet;
          address.city = entryCity;
          address.state = entryState;
          address.zipcode= entryZipcode;
          entriesCount++;
     public void setName(String entryName){
          name = entryName;
     public void setStreet(String entryStreet){
          address.street = entryStreet;
     public void setCity(String entryCity){
         address.city = entryCity;
     public void setState(String entryState){
          address.state = entryState;
     public void setZipcode(String entryZipcode){
          address.zipcode = entryZipcode;
     public String getAddress(String entryName){
          return address.toString();
     public String getName(){
          return name;
     public String toString(){
          String addressString = address.getStreet() + "\n"
                                             + address.getCity() + "\n"
                                           + address.getState() + "\n"
                                           + address.getZipcode() +"\n";
          return addressString;
     public static int getEntriesCount(){ return entriesCount;}
Driver Class
import javax.swing.*;
public class AddressBookApp{
public static void main (String args[]){
     String choice = "";
     while(!(choice.equalsIgnoreCase("x"))){
          String name = JOptionPane.showInputDialog("Enter name : ");
          String streetAddress = JOptionPane.showInputDialog("Enter street address : ");
          String city = JOptionPane.showInputDialog("Enter city : ");
          String state = JOptionPane.showInputDialog("Enter state : ");
          String zipcode = JOptionPane.showInputDialog("Enter zipcode : ");
          AddressBookEntry bookEntry = AddressBookEntry(name,street,city,
                                                  state,zipcode);
          String message = "Name : " bookEntry.getName() "\n"
               + "Address : \n"+bookEntry.toString();+ "\n"
          +"Press Enter to continue or 'x' to exit.";
          choice = JOptionPane.showInputDialog(message);
System.exit(0);
}

Can somebody help me in notifying the thread from junit class.

I am writing a junit test case for the following kind of scenario.
There is a private inner class B that is enclosed with in class A.
class A
int i=1;
B threadB;
void AFun()
while(i<10)
threadB=new B();
threadB.start();
if(i%2==0) {
i++;
threadB.notifyThread();
private class B extends Thread
void run()
while(true)
System.out.println(i);
i++;
waitThread();
if(i==10) {
break;
public synchronized void waitThread(){
try {
this.wait();
} catch (InterruptedException e) {
e.printStackTrace();
public synchronized void notifyThread(){
this.notify();
now i want to notify class B from the junit class ATest if the thread is in waiting state.. is there any way to notify the class B threadB from test class.
//JUNIT Class
Class ATest
Class c;
A a=new A();
c=a.getClass();
Field BThread=c.getDeclaredField("ThreadB");
BThread.setAccessible(true);
Object obj=BThread.get(a);
a.AFun();
while(true){
if(((Thread)obj).getState()==Thread.State.WAITING)
// Is there any way to notify the thread B that is waiting or to call notifyThread of private class B over obj
}

Well, sinced no one has any ideas, here's my two cents worth.
You can create a public static class variable in either Class A or Class B. as follows:
public static String temp;
Then either class can change the value by having this in a function:
ClassA.temp="abc"
and either class can read it from within a function by calling
String n1= ClassA.temp;
If you want to get fancy, you can put use a java collection instead of a string. The collection will store various information on what your doing such as which class changed the value and when.

How to create a constructor for this 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
tim

If you have no constructor you cant instanciate (I know i just murdered that spelling) the object.
Malfl�che thisHereThingie = new Malfl�che()assuming that you want to run that class by itself you will need a main method that has the preceeding code in it. If you are running it from another class you need to instanciate it... but anyway at the very least for a constructor you need.
public Malfl�che(){

12.4 beta: private copy constructor in base class required to be called from temporary reference when -g option used

Hi,
We've got an abstract base class (StringBase) which various types of strings inherit from. The copy constructor for this base class is private, since we don't want to allow copying when this class shouldn't be directly instantiated. A number of our methods take specify the base class as a reference, but take a derived class temporary as a default argument (see code appended).
This worked fine in 12.3, but in 12.4 beta, this now says:
   Error: StringBase::StringBase(const StringBase&) is not accessible from __dflt_argA().
This works fine in clang and gcc, and indeed, this GNU document says it was a bug which was fixed in gcc 4.3.0:
    Copy constructor access check while initializing a reference
which references http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_defects.html#391
It only appears to error when the "-g" option is used, however, which doesn't seem right, and compiles fine if the "-g" option is removed, which makes me think it's a bug. Presumably the optimizer is eliding the copy when not using -g, but it's left in for debug mode, causing the compile error?
Many thanks,
Jonathan.
$ clang++ -std=c++11 defaultarg.cpp
$ g++ -std=c++11 defaultarg.cpp
$ /opt/SolarisStudio12.4-beta_mar14-solaris-x86/bin/CC -c defaultarg.cpp
$ /opt/SolarisStudio12.4-beta_mar14-solaris-x86/bin/CC -g -c defaultarg.cpp
"defaultarg.cpp", line 6: Error: StringBase::StringBase(const StringBase&) is not accessible from __dflt_argA().
1 Error(s) detected.
$ cat defaultarg.cpp
#include "stringbase.h"
#include "conststring.h"
static const ConstString S_DEFAULT("default value");
void SomeMethod( const StringBase& str = S_DEFAULT )
   (void) str;
int main( void )
   SomeMethod();
$ cat stringbase.h
#ifndef STRINGBASE_H
#define STRINGBASE_H
class StringBase
protected:
   StringBase() {}
private:
   StringBase( const StringBase& );
#endif
$ cat conststring.h
#ifndef CONSTSTRING_H
#define CONSTSTRING_H
#include "stringbase.h"
class ConstString : public StringBase
public:
   ConstString() {}
   ConstString( const char* ) {}
   ConstString( const ConstString& );
#endif

Thanks for reporting the problem!
This looks like a compiler bug, I think an artifact of creating a helper function for the debugger for the default argument.
I have filed bug 18505648 for you.

Invoke super class constructor of super class' parent class

I would like to invoke a constructor of a super class that is the parent of the direct super class. For instance:
class C extends class B, and class B extends class A.
From class C, is it possible to invoke class A's constructor without first invoking class B constructor?
Something like super.A() ??
Thanks.
Joe

try this,
abstract class GrandParent
      private Object pObj = null;
      protected Via via = new Via();
      protected class Via
         public Object doMethod1( Object obj )
            pObj = obj;
            return "GrandParent m1: " + pObj;
         public Object doMethod2( Object obj )
            pObj = obj;
            return "GrandParent m2: " + pObj;
         public Object get()
            return "gp get: " + pObj;
      public abstract Object doMethod1( Object obj );
      public abstract Object doMethod2( Object obj );
      public abstract Object get();
class Parent extends GrandParent
      private Object pObj = null;
      public Object doMethod1( Object obj )
      pObj = obj;
      return "Parent m1: " + pObj;
      public Object doMethod2( Object obj )
      pObj = obj;
      return "Parent m2: " + pObj;
      public Object get()
      return "p get: " + pObj;
public class GPMethod extends Parent
      public static void main( String[] args )
      GrandParent gp = new Parent();
      System.out.println( gp.doMethod1( "calling parent" ) );
      System.out.println( gp.doMethod2( "calling parent m2" ) );
      System.out.println( gp.get() );
      System.out.println( "" );
      System.out.println( gp.via.doMethod1( "calling via to GP" ) );
      System.out.println( gp.via.doMethod2( "calling via to GP m2" ) );
      System.out.println( gp.via.get() );
}

Easy One: Constructor of Child Classes

Hello. I am new to the java language and i have a question.
I want to make a Class Vehicle which should have the following variables
static int id;
static long color;
static String brand;
static Boolean rented;
static String location;
Now i want to make a Child class called 'Car' which should have the .location set to "land" by default.
I want to also make a Child class of 'Car' called 'Bus' .
Now the problem is with the constructors. I want that when i create a class Bus that the .location is set to "land" automatically and not with user input. This means it will call the constructor of 'Car' and not 'Vehicle' which sets .location to "land"
I tried to do so but it tells me 'Constructor Car() was not found' .
I want the constructor of Car define the .location="land" but the constructor of Bus will not have the .location argument because
it is set to "land" by default?
Please help !
thanks
code follows:
package map_exercise;
* Title:
* Description:
* Copyright: Copyright (c) 2003
* Company:
* @author
* @version 1.0
public class Vehicle {
static int id;
static long color;
static String brand;
static Boolean rented;
static String location;
public Vehicle(int myid,long mycolor,String mybrand,Boolean isrented,String mylocation) {
this.id=myid;
this.color=mycolor;
this.brand=mybrand;
this.rented=isrented;
this.location=mylocation;
package map_exercise;
* Title:
* Description:
* Copyright: Copyright (c) 2003
* Company:
* @author
* @version 1.0
public class Car extends Vehicle {
public Car(int myid,long mycolor,String mybrand,Boolean isrented) {
super(myid,mycolor,mybrand,isrented,"land");
package map_exercise;
* Title:
* Description:
* Copyright: Copyright (c) 2003
* Company:
* @author
* @version 1.0
public class Bus extends Car {
public Bus(int myid,long mycolor,String mybrand,Boolean isrented) {
}

I agree with NadjaS about the general remarks on the use of static vs. instance variables.
Anyway, if you really need to keep the variables at the class definition level, you can initialize them through the static initializer constructor within the "Car" class itself, i.e. something like this:
public class Car extends Vehicle {
static {
location = "land";
}without necessarily calling the super constructor.
The message "Constructor Car() was not found" is due to the fact the the only Car class constructor has four parameters - hence a completely different signature - and there is no constructor without parameters at all.
Hope this will help.
Bye

Constructors in Junit classes?

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