#Need help with classes in Java very basic

143 messages · Page 1 of 1 (latest)

fresh bone
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I need help with a java program im writing I have a class called Record which im trying to use in another class, I dont know if I'm doing something wrong but it seems that Vscode is using a standrd Record class (Java.lang.record). I dont know how to change it sothat it uses the custom class I made, I cannot change the name of the class and both files are in the same folder.

sour monolithBOT
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brittle parrot
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You need delete import Java.lang.record and reimport you Record class.

fresh bone
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i have not imported anything in this particular file

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how do i delete an import that was never there

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and i thought if the files are in the same folder you dont need to import them?

brittle parrot
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You can use your own Record class by put package path in font of Record like : com.you.package.path.Record record = new com.you.package.path.Record();

weak ether
fresh bone
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idk what that is?

fresh bone
gray tree
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import your.package.Record;

fresh bone
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how do i import a specific file

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both files are already in the same folder

gray tree
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can you share the files

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do they have package declarations at the top?

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and how are you running them

fresh bone
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record.java, stores a key from class key

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in binarysearchtree to get a node with a given key i need to pull the record from the node and the get the key

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but it says getKey() not defined for Record

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and when i scroll over Record witgh my cursor it says Java.util.record

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all files are in the same folder so it should use Record.java no?

brittle parrot
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Maybe you import java.lang.record in BSTDictionary.java ? So when you get record from dictionary that is java.lang.record not your defined Record class.

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I can check if you upload your BSTDictionary.java

fresh bone
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i have the ADT for that but have not implemented it yet

brittle parrot
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emm You should implement BSTDictionaryADT first, and be sure that get method return Record is you defined.

indigo haven
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"I cannot change the name" is just not gonna cut it.

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There would be a solution if you were using packages. But as you don't, you don't have any way to counter the fact that java.lang classes are auto-imported

brittle parrot
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Yes you should avoid to use the word that was defined in jdk as system key words.

indigo haven
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Record with a capital R is just the supertype of all records. There would be much more compilation failures trying to use a keyword like a class name

fresh bone
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unfortunately I dont get to choose its an assignment for a class and we have to follow the instructions

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I could lose marks for messing with the name as they probably have test cases which they use to run everybodys code with the the same name files

fresh bone
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wouldnt it still return the wrong object Record

brittle parrot
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ok upload your package,i will check what's wrong

fresh bone
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as inthe whole folder?

brittle parrot
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yes

indigo haven
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I mean, it works fine on some IDEs. But that kind of layout is rather confusing on how to build compilation lines

brittle parrot
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You're right,these engineering regulations are things that teachers never tell us, but they are very important in work project.

fresh bone
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how do i submit a whole folder

brittle parrot
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Maybe use compression tool to compress folder

fresh bone
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this is a zip with all provided code the files i sent earlier were added by me

brittle parrot
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Ok, first you need modify java.lang.Record to Record all the class and interface

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You should organize the directory structure of you project, you should not pull all the files in one directory.

fresh bone
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how do i do this?

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are you on vscode?

brittle parrot
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No. I use IDEA and I recommend you use it.

sour monolithBOT
#

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fresh bone
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ok so how do i solve the issue im sorry i dont understand the instruction

sour monolithBOT
gray tree
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oh hmm

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try writing import Record;

fresh bone
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well its supposed to come from my class in file Record.java

gray tree
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if that doesn't work this might be a strange corner case or the language

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i need to read the language spec

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defintiely one fix is to put things in a package

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so

package program;

public class Record{

private Key theKey;
private String data;

public Record (Key K, String theData){

    this.theKey = K;
    this.data = theData;
}

public Key getKey(){
    return theKey;
}

public String getDataItem(){
    return data;
}


}
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and then

# 
import program.Record;

public class BSTNode {
    
    private Record record;
    private BSTNode leftChild;
    private BSTNode rightChild;
    private BSTNode parent;

    public BSTNode(Record r) {
        this.record = r;
        this.leftChild = null;
        this.rightChild = null;
        this.parent = null;
    }
    public Record getRecord() {
        return record;
    }
    
    public void setRecord (Record d){
        this.record =d;
    }

    public BSTNode getLeftChild(){
        return leftChild;
    }

    public BSTNode getRightChild() {
        return rightChild;
    }

    public BSTNode getParent() {
        return parent;
    }

    public void setLeftChild(BSTNode u) {
        this.leftChild = u;
    }

    public void setRightChild(BSTNode u) {
        this.rightChild = u;
    }

    public void setParent(BSTNode u) {
        this.parent = u;
    }

    public boolean isLeaf(){
        boolean retBool = false;
        if (this.leftChild == null && this.rightChild ==null && this.getRecord() == null){
            retBool = true;
        }
        return retBool;
    }


}
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but give me a minute to read the language spec

fresh bone
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ok

gray tree
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if you want to read along

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@fresh bone so uhh

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this is impossible to fix unless you move code into packages

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🤷‍♂️ 😬

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good time to learn how to do that I guess

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how are you compiling/running your code right now?

fresh bone
gray tree
#

🙃

fresh bone
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didn’t get that far

gray tree
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who wrote this code?

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is this like "starter" code for an assignment?

fresh bone
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which part i wrote, Record, BSTNode and Key

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the rest was provided files for an assignment yes

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so yes starter code for an assignment 😭

gray tree
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you need to tell your professor about this so they can let you either

  • Move things into packages
  • Rename Record to something else
fresh bone
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im on call with a teaching assistant right now and he cant figure anything out either

gray tree
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I am 95% sure there is no way to fix this other than those two ways

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...or compiling with a lower release

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so like javac --release 11 -d out *.java

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that would actually work

fresh bone
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aasted a whole day on this

gray tree
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can you use the --release flag?

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when you compile

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that should do it

# 
javac --release 11 -d out *.java
TestDict.java:7: error: cannot find symbol
        BSTDictionary dictionary = new BSTDictionary();
        ^
  symbol:   class BSTDictionary
  location: class TestDict
TestDict.java:7: error: cannot find symbol
        BSTDictionary dictionary = new BSTDictionary();
                                       ^
  symbol:   class BSTDictionary
  location: class TestDict
TestDict.java:151: error: cannot find symbol
        dictionary = new BSTDictionary();
                         ^
  symbol:   class BSTDictionary
  location: class TestDict
3 errors
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did you make a BSTDictionary yet?

# 
class BSTDictionary implements BSTDictionaryADT {

    public Record get (Key k) { return null; }

    public void put (Record d) throws DictionaryException {}

    public void remove (Key k) throws DictionaryException { }

    public Record successor (Key k) { return null; }

    public Record predecessor (Key k) { return null; }

    public Record smallest () { return null; }

    public Record largest () { return null; }
}
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I made this dummy BSTDictionary

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then compiled with

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javac --release 11 -d out *.java

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and it works fine

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actually..

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it works fine regardless?

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are you sure you are doing this right?

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its all working for me locally

fresh bone
fresh bone
gray tree
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how are you running your code?

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what editor are you using

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what is "not working" exactly

fresh bone
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ok so i was on vscode

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and for some reason you cant see the file structure properly in the explorer on vscode

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but my TA opened it up on eclipse and saw that Record.java was in the folder with everything else but was not in "default package"

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idk how or why as I created it and saved it the same way

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do you know why this couldve happened?

fresh bone
fresh bone
gray tree
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If im real about it - VSCode is not great for Java ATM

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it is getting better but slowly

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download the community edition (link is in the black area)

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and make a blank new project

fresh bone
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one more question

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whats the difference between the BinarySearchTree and the BSTDictionary classes

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arent they applying the same methods

gray tree
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im doing thanksgiving prep

pearl palm
#

If youre interested, you should download Eclipse. I find it much better to work with Java in than visual studio code. If you have any questions feel free to DM me.

fresh bone
gray tree
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okay looking

fresh bone
gray tree
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I don't see a BinarySearchTree class

fresh bone
gray tree
#

ah

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so BinarySearchTree is the generic structure

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BSTDictionary seems to make a dictionary on top of it

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so inside BSTDictionary you likely will have to use BinarySearchTree

fresh bone
gray tree
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doesn't look like it