What's the name of the structure like its: "foo.bar.class"

[swift meteor]

tiny question

[upper acorn]

<@&987246964494204979> please have a look, thanks.

[upper acorn]

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The structure you are referring to is called a package structure in Java.

[torn dagger]

fully qualified name class type

[crisp ingot]

it kinda depends on the context

java.util.Scanner here u have a package and then the name of the class

but nothing holds u back from naming ur classes with lower case

and then it could also be inner classes

such as in java.util.ArrayList.Iterator

Iterator being an inner class of ArrayList

and java.util being the package its in

but yeah, in the end its called the "fully qualified name" of a class

like its "full address"

[swift meteor]

wait, is the "java.util.Scanner" just a representation of the the equivlent file directory .\java\util\Scanner?

[crisp ingot]

yes

packages are supposed to be represented in file hierachy

(theres a flag to tell javac to ignore that, but still)

[swift meteor]

so if i have my class like this .\build\MainClass it would be like build.MainClass

[crisp ingot]

no

packages are first and foremost a concept in ur java code

when u create a class, the first line denotes the package its in

package foo.bar;

public class Test {
  ...
}

the Test class is in the package foo.bar

its full name is foo.bar.Test

and javac wants u to represent this package hierarchy also in folder structure

so ur supposed to put it in a foo/bar/Test.java

[swift meteor]

so it's exclusively used for packages or is this thing use for other things?

[crisp ingot]

but that doesnt mean that all folders are automatically packages

the part that makes a package is this first line in the class

[swift meteor]

hm

[crisp ingot]

packages are part of accessibility control

[swift meteor]

could i ask you a question about manifests?

[crisp ingot]

u know, theres public, protected, private and if u dont write anything, u get "package-visible"

so packages are for package-visibility

and ultimately are used to organize ur code in a meaningful way

similar to folders

hence why ur also supposed to represent them with folders

[crisp ingot]

just do it

[swift meteor]

ay

right now i've had troble getting my .jar file to world, as every time i run it using java -jar helloWorld.jar it responds with "could not find main class"

What i use to compile from .class \Test build> jar cfm build-1.jar .\build\Manifest.txt .\build\helloWorld.class

i think it's a issue about the manifest pointing the wrong way, as rn i have it as main-class: helloWorld

[crisp ingot]

dont write the manifest urself

let ur IDE do it

can u share ur current manifest?

[swift meteor]

ay

[crisp ingot]

can u share the full helloworld file

the java, not class

[upper acorn]

I uploaded your attachments as Gist.

Here is an example of a Java JAR manifest file with a main class entry:

Manifest-Version: 1.0
Main-Class: com.example.MainClass

In this example, the main class entry is specified as com.example.MainClass. Replace com.example.MainClass with the fully qualified name of your main class.

[crisp ingot]

ur class needs to be public

and perhaps u also need to put it in a package

im not sure if jars work with the "default package"

btw import java.lang.Math; is obsolete. anything from the java.lang package is auto-imported implicitly

and this myObj.close(); is technically a bug

u must not close scanners tied to System.in

only if they are tied to files or similar

[swift meteor]

god i know so little about java

[crisp ingot]

dont worry

[swift meteor]

How can i do this? just add the public keyword at line 4?

[crisp ingot]

yes. public class Foo {

[swift meteor]

it giving the error: say the public type needs to be it's own file

[crisp ingot]

then u did a mistake

gonna share the code

or ur misinterpreting the error

would be good if u share the actual error message

[crisp ingot]

whats the name of ur file

i suppose its not helloWorld.java?

[swift meteor]

same as class...

[crisp ingot]

i doubt

look at the case as well

u likely called it HelloWorld.java or helloworld.java or sth

but not helloWorld.java

[swift meteor]

Well i use the class name for the .class file

so helloWorld.class

exact same

[crisp ingot]

can u please just share a full screenshot of ur IDE window

with the class name, the code and the error message in it

full screenshot

[swift meteor]

Sc

[crisp ingot]

a full screenshot please

of ur entire IDE window

but i can already see that u called it 0.java

instead of helloWorld.java

[crisp ingot]

a general note: visual studio code is a really bad IDE for writing java code. every second user asking here for help with some IDE related problem is using VSC

[crisp ingot]

https://i.imgur.com/XN1kOtc.png

see, ur file is called 0.java

it must be called helloWorld.java

[swift meteor]

dose the name effect the compiling to a class file?

ah

[crisp ingot]

yes

[tight wagon]

id also recommend yout to follow standard java naming conventions

so the class should be called HelloWorld