Doubt on 'default' access modifier

How JRE access the main method even if the class has 'default' access.
ie, following run without declaring the class as public.
As per my understanding only classes in the same package access the method. Is the 'default' package belong to JRE ?
class a {
public static void main(String args[]){
System.out.print("Welcome");
}

I am getting following error when I tried to run from command prompt.
Exception in thread "main" java.lang.UnsupportedClassVersionError: HelloWorldApp
(Unsupported major.minor version 50.0)
at java.lang.ClassLoader.defineClass0(Native Method)
at java.lang.ClassLoader.defineClass(Unknown Source)
at java.security.SecureClassLoader.defineClass(Unknown Source)
at java.net.URLClassLoader.defineClass(Unknown Source)
at java.net.URLClassLoader.access$100(Unknown Source)
at java.net.URLClassLoader$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClassInternal(Unknown Source)

Similar Messages

Usage of default access modifier

Some programmers don't use the default access modifier (package level). Is there a specific reason? If so, what is it? Or is it a good to use default access modifier?
Thank you,
Srikanth

Some prefer to grant or limit access to an object by the interface they expose. In this case all methods are either public or private. Access is restricted based on the fact that only the appropriate code is given references of certain interface types and if code does not have the right interface, they can not access the method.
Its a different style, but I use it myself quite a bit. This way I never am concerned over if it should be public,private, protected or default. The choice is simpler. But sometimes it can make you create interfaces for really simple things which I am not uptight enough to do...

Default access modifier

Hello,
Can someone tell me what the default access modifier is in Java:
-for methods
-for member variables
Thanks in advance,
Balteo

Friendly. Accessible to any other classes in the package.

Default access modifier in Interface

public interface Inter
     protected void print();
}Doesn't compile. Error Message is Modifier protected not allowed here.
public interface Inter
void print();
above code compiles fine. I was thinking since default access is more resctricted than protected it should not have been compiled either.
am i wrong??

Try implementing an interface with an access other than public in a different package.Your wish is my desire! Voila, p1.a is not a public interface and p2.c still implements it circumventing the impossiblity to directly use the "implements" keyword.
package p1;
interface a {
void doit();
package p1;
public class b implements a {
        public void doit() {
package p2;
public class c extends p1.b {
package p1;
public class d {
        public static void main(String a[]) {
                Object o = new p2.c();
                if (o instanceof a) {
                        System.out.println("A miracle! "
                                + o.getClass().getName()
                                + " implements "
                                + a.class.getName()
}$ javac -d . *.java
$ java p1.d
A miracle! p2.c implements p1.a

Regarding Default access modifier

Hi All,
There is a rule saying that...there must be one public class per source file and the file name must match with the class name.
What about having a class with default access level?I have a file having only one class (same as the file name) with default access level.It is working fine...
My question is...With default access, a class can be accessed inside the same package, but not from outside.Then..How come JVM is able to run that class?
What am I thinking is correct? or Am I going wrong?
Can anybody make it clear?
Thanks

What about the rule saying..
There must be one public class per source file and
the file name must match with the class name?I think you have misinterpreted. You can have at most one public class per file. If one class is public then all others cannot be public.

Default class access modifier

What is the default access modifier for a class? I can't seem to find it in the tutorials...
Thanks
Jim

The default access is the same for top level classes that do not specify access explicitly as for other identifiers. Package.
This single source file will create two class files in the same package. Only other classes in the package can see these top level package access classes.
And, yes, this is a bad idea. In the case of some build tools, errors in a compile can cause the public class to compile, but the package class to fail. After that, the compiler will not be able to determine what source file to compile for the package level class. This is an error that confuses many developers. I do not recommend this practice. Put each top level class in its own source file.
� {�

Default/package/none access modifier

Hi,
I was hoping for some discussion on the default/package/none access modifier. It's always really bugged me that we have public, private, protected, and then "none", while it seems to me that it would be less confusing, and more consistent to use the keyword "package", or maybe even "default".
Then, source code would look like
public class MyClass{
    public int getValue() {}
    private void setValue() {}
    protected void someMethod() {}
    package int justForPackage() {}
}I know this concept has come up before, but the books I've read which mention this topic haven't offered any actaul justification/explanation for why there isn't some keyword.
Anyway, are there any insights as to why java is this way, and any reasons why java should or shouldn't be changed to include the package access modifier.

A good example is within a tightly grouped package (usually should be this way) you may have some cooperative classes that access methods.
// one .java file
public class SomeHelper {
   private void method() {
     new ClassForUsers().accessHiddenLogic();
// next .java file in same package
public ClassForUsers {
    /* default-access */ void accessHiddenLogic() {
}But, you may want to allow users to subclass your ClassForUsers, without giving them access to the hidden logic method directly:
// another .java file in a different package
public class UsersSubclass extends ClassForUsers {
    public void userMethod() {
        // can't do this
        accessHiddenLogic();
}This could be for either business logic or security reasons. So, package level access can be very useful. However, I've seen that in practice it is avoided because it isn't obvious what is going on.

Non access modifier: default

Top of the morning.
Im studying for my SCJP exam and I have 2 text books.
One of the text books asks the following question:
(Im only writing the one answer im sceptical about)
which of the following declarations are illegal?
A. default String s;The answer at the back says that the above is illegal because defaultis not a keyword. But am I right in saying that unless you explicitly declare a class member
as having one of the 4 access levels, it is automatically give default access - so in essence
writing default is redundant if you don't give the member private, public or protected access.
Nevertheless you could write default String s; couldn't you?
The above declaration does compile.
Thanks

shamrock08 wrote:
The answer at the back says that the above is illegal because defaultis not a keyword. [It is|http://java.sun.com/docs/books/tutorial/java/nutsandbolts/_keywords.html], it is just not one [related access|http://java.sun.com/docs/books/tutorial/java/nutsandbolts/switch.html].
The above declaration does compile.It does not in Eclipse. Lets see your compiling code.
Nevertheless you could write default String s; couldn't you?
No.

Access modifier for Constructors ???

As constructors are not the so called Members of a class
(Class's Member declarations include only 4 things : variables , methods, member classes and member interfaces)
Why do we have access modifiers for constructors also ??
I know that if a class A 's constructor is declared 'private' , then that class cannot be instantiated outside the class A. .That is, class A can be instantiated only inside class A and provide this newly created reference to the outside world through public getter method.
I dont understand how the other access modifiers (protected and default ) apply to a constructor.
Any help from ur side is greatly appreciated !!!!!

Why do we have access modifiers for constructors also
??To prevent anyone from accessing them if they shouldn't.
I know that if a class A 's constructor is declared
'private' , then that class cannot be instantiated
outside the class A. Or you use another c'tor. Or a static getInstance() method provided by A. You you simply shouldn't create an instance yourself anyway.
That is, class A can be
instantiated only inside class A and provide this
newly created reference to the outside world through
public getter method.Yepp.
I dont understand how the other access modifiers
(protected and default ) apply to a constructor. Same as at other places. No difference.

Protected and public access modifier - exact difference

Hi everybody,
Please help me to give an exact difference between protected access modifier and public
Protected: Classes with in the same package as well as subclasses can access.
Public : Classes outside the current class can access while declaring public.
My doubt is that what is the practical difference between public and protected.
I searched the net , but the information was not satisfactory to solve my confusion.
Thanks & regards
Parvathy

Obviously doubt = lacks the ability to think for
oneself.When one person raises a doubt, that does n't mean that he lacks the ability to think . He/She might have thought about it and if he didnt get a proper clarification then it will be posted in the forum.
In such cases please dont discourage others who are ready to answer the subject.Without knowing the actual intention , i request you please dont reply like this

Private, protected Access Modifiers with a class

Why cant we use private and protected access modifiers with a class?
Thanks.

Matiz wrote:
>
Public access allows you to extend a parent class in some other package. If you only want users to extend your class rather than instantiate it directly, make the class abstract and design for extension.Agreed. However, would the same argument be not true for the default access at the class level? No. Default access would only allow you to extend a parent class in the same package (as opposed to some other package).
Now my confusion is why is a class allowed default access at the top level and not protected?Because protected for a top-level class makes no sense. The protected keyword provides member access to any other class in the same package and extending classes outside the package. A top-level class isn't a member of a class, by definition, so there's nothing that protected would do provide differently than public.
So, the two access modifiers for a top-level class are public and default. Public allows access to the class outside the package, whereas default restricts access to the class within the package.
~

Access modifiers

I dint understood the below question properly, please help me out.......
You want subclasses in any package to have access to members of a superclass. Which is
the most restrictive access that accomplishes this objective?
A. public
B. private
C. protected
D. transient
E. default access
I want to know whether the question is relating to class access modifiers or methods and variables of the classes...

I didnt get you, please explain the topic properly.... I think classes can have only public and default as an access modifier, is it rite??? That's right. Look at [this,|http://java.sun.com/docs/books/tutorial/java/javaOO/accesscontrol.html] it will give you a better understanding of the topic than you'd get from me answering your question.

Access Modifiers, Package declaration

I created the following two classes in the same folder as two source files:
A.java
package abc;
class A{
B.java
package abc;
class B extends A{
When I tried to compile, A compiled successfully. But when compiling B, it gives an error Cannot find symbol for class A.... I think it should be visible as both class access modifiers are (default). Why do I get this error????
By the way if package declarations are removed from both classes then they compile successfully........

i tried a lot..... does classpath affects compilation??? can u correct dis???If we're going to make the effort to help you, you could show willing and make the effort to spell out all your words and generally make your sentences as easy to understand as possible.
Yes, the classpath affects compilation as the link provided shows. YOU can correct this.
>
e:\one\>javac -classpath e:\one\cert B.java
>
The classpath points at directories (or JAR files) not Java source files. Read the link.

What is the difference between access specifiers and access modifiers?

what is the difference between access specifiers and access modifiers? are they same? if not what is the difference.

Access Specifier are used to specifiy how the member variable ,methods or class to other classes.They are public ,private and protected.
Access Modifier:
1.Access
2.Non Access
Access:
public ,private,protected and default.
Non Access:
abstract,final,native,static,synchronized,transient,volatile and strictfp

Default access class

I tried searching for this but couldn't find it. If you have a package-access class, are there any special rules on access modifiers allowable for variables and methods?
Thanks.

No.Good answer.
http://java.sun.com/docs/books/tutorial/java/java
OO/accesscontrol.html
http://java.sun.com/docs/books/tutorial/java/java
OO/classdecl.html
http://java.sun.com/docs/books/tutorial/java/java
OO/index.html
http://java.sun.com/docs/books/jls/third_edition/
html/j3TOC.html
Offset your good answer with these useless links.
So, why is there no restriction? If you have a default-access classes but public (or protected?) members, wouldn't they still not be accessible for that class? Though it could just be another "simply memorize it" rule, are there any reasons you might think of for why it's done like that?

Doubt on 'default' access modifier

Similar Messages

Maybe you are looking for