Frequent question: Is it mandatory to have a public class in Java?

java file without a public class. Okay, so a java source file must have at least one public class and the file should be called “class-name.

Can a Java file have no public class?

2 Answers. The actual requirement is slightly different: every Java public class must be in a compilation unit with the name PublicClassName. java . But it’s perfectly fine to have a compilation unit that does not contain a public class.

Why should there be only one public class in Java?

There can be only one public class in a java file because the name of java file is same as the name of public class. And obviously we can’t have a file with two different names.

Should classes be public or private?

We should use public access modifier if we want to make the method or property visible from anywhere, other classes, and instances of the object. Use the private access modifier if you want to make the method or property visible in its own class only. Avoid public fields except for constants.

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What does no public class mean in Java?

The class with main() needs to be public. No keyword means that it’s package private: only classes that are in same package can access it.

Can we have a class without the public?

It’s not public unless you use the keyword. Default (without any keyword) visibility means that your class visible inside package where it defined. The default access level is different from public, protected and private – so a class is not by default public if you don’t add one of those three keywords.

What is mandatory in Java file?

class inside that. It’s mandatory that class files reside on the same package or directory as declared in their source file using package keyword, failure to do will result in java. lang.

Can a package have more than one public class?

Yes it can,but there can only be 1 public class inside any package as java compiler creates the . Class file which is of the same name as the Public class name therefore if their are more than 1 public class it would be difficult to select for compiler that what should be the name of Class file.

Can abstract classes be final?

No, An abstract class can’t be final because the final and abstract are opposite terms in JAVA. Reason: An abstract class must be inherited by any derived class because a derived class is responsible to provide the implementation of abstract methods of an abstract class.

Should java classes be in separate files?

It is technically legal to have multiple Java top level classes in one file. However this is considered to be bad practice (in most cases), and some Java tools may not work if you do this. The JLS says this: When packages are stored in a file system (§7.2.

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What is difference between public class and normal class in Java?

What is the difference between a public and a non-public class? A class with access specifier ‘public’ can be accessed across the packages. … If a class is specified protected access can be accessed in other packages but only by the subclasses. The class without access specifier can be accessed only within the package.

What is difference between public and private class in Java?

Public members can be accessed from the child class of the same package. Private members cannot be accessed from the child class of the same package. Public member can be accessed from non-child class of same package. Private members cannot be accessed from non-child class of same package.

What is public class Main in Java?

Java objects are part of so-called “Java classes”. … The first line defines a class called Main. public class Main { In Java, every line of code that can actually run needs to be inside a class. This line declares a class named Main , which is public , that means that any other class can access it.

Can a non public class have main method?

“for sure we can have a file with main method inside non-public class and it will compile as well as run successfully, but make sure that at the time of running the program we have to pass the class name of “main method” to the java interpreter instead of the class which is public.”

Should the main class be public?

The main method must be declared public, static and void in Java otherwise, JVM will not able to run Java program. 2. JVM throws NoSuchMethodException:main if it doesn’t find the main method of predefined signature in class which is provided to Java command. … The main method is an entry point for any Core Java program.

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What happens if main method is not public?

I mean if the class itself is not public JVM can still access main method that means there is no need of main to be public. But if we don’t declare it as public, it will throw an error.

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