logo
down
shadow

Collections.max function is returning hashcodes (I think)


Collections.max function is returning hashcodes (I think)

By : faisalalicpy
Date : November 22 2020, 10:38 AM
help you fix your problem System.out.println(maxTree);calls toString() on maxTree. Since you did not override it, it calls the method on Object, which just outputs the full class name and some additional information.
You need to implement toString()yourself to get an more readable output.
code :
public class Tree {
    public double suitability = Math.random();
    public int id;
    public static int count = 1;

    public Tree(double suitability, int id) {
        this.id = count;
        count++;
    }

    public double getSuit() {
        return suitability;
    }

    public void setSuit(double suitability) {
        this.suitability = suitability;
    }

    public void measureSuit() {
        System.out.println("Tree number " + id + " has a suitability of " + suitability);
    }

    @Override
    public String toString() {
        return "I am the tree with id " + id;
    }
}


Share : facebook icon twitter icon
Java Hashtable .containsKey(String key) is returning true even when the strings and hashcodes are different... How?

Java Hashtable .containsKey(String key) is returning true even when the strings and hashcodes are different... How?


By : user2946601
Date : March 29 2020, 07:55 AM
I wish this help you I've reread your question, and as I understand it you have the following problem:
You do
code :
bol.containsKey(current.key)
bol.put(somePuzzle.key, somePuzzle)
How hashcodes for enums are calculated in Java, and combining enum hashCodes for a HashMap's key

How hashcodes for enums are calculated in Java, and combining enum hashCodes for a HashMap's key


By : Big Al
Date : March 29 2020, 07:55 AM
fixed the issue. Will look into that further Yes, you are right in that the hashcode of an enum element will come from the static instance, bound to memory positions, and be unique.
On the other hand, there are better ways of generating a hashcode with less collision probability. Check out, for example, the defaults that eclipse can autogenerate for you (right click, Source> Generate hashCode and equals)
code :
public int hashCode() {
    final int prime = 31;
    int result = 1;
    result = prime * result + ((enum1 == null) ? 0 : enum1.hashCode());
    result = prime * result + ((enum2 == null) ? 0 : enum2.hashCode());
    return result;
}
VersionControlServer.QueryHistory returning System.Collections.IEnumerable / System.Collections.Generic.IEnumerable

VersionControlServer.QueryHistory returning System.Collections.IEnumerable / System.Collections.Generic.IEnumerable


By : Orlando Fernando Mar
Date : March 29 2020, 07:55 AM
I wish this helpful for you If you're sure the collection only contains ChangeSet items you can use the Linq extension method Cast():
code :
IEnumerable myCollection = ...
IEnumerable<ChangeSet> myGenericCollection = myCollection.Cast<ChangeSet>();
IEnumerable myCollection = ...
IEnumerable<ChangeSet> myGenericCollection = myCollection.OfType<ChangeSet>();
Objects.hash returning different hashCodes for equal objects

Objects.hash returning different hashCodes for equal objects


By : user3643350
Date : March 29 2020, 07:55 AM
This might help you As you noted, if objects A and B are equal (in the sense that A.equals(B) returns true, they should have the same hash code. By extension, if you implement your equals method by checking the equality of a series of fields, using Objects.hash should provide a proper hashcode.
But this isn't what you're doing here - you're using Arrays.equals to compare two arrays - as you should. Arrays with the same contents are not equal, and thus may (and probably will) have different hash codes. Instead, you can use Arrays#hashCode to get value's hash code:
code :
@Override
public int hashCode() {
    return Objects.hash(owner, Arrays.hashCode(value));
    // Here -------------------^
} 
Collections.sort Hashcodes

Collections.sort Hashcodes


By : quinn
Date : March 29 2020, 07:55 AM
I hope this helps . A List is an ordered collection. This means that a List with [1, 2] is not equal to a List [2, 1] nor should the hashCode() be the same (ideally)
When you sort the collection you change it's order and thus it's hashCode. Note this is not guarenteed for all types. e.g. all Long of the formula ((x + y) & 0xFFFFFFFF) + y << 32) have the same hashCode for the same value of x. This means you have a list of Long where each long has the same hashCode and thus the list of these numbers will have the same hashCode regardless of order.
Related Posts Related Posts :
  • Repeating for loop in menu
  • Can Java garbage collector randomly delete objects in the On-Heap tier?
  • Apache CXF Exception: SSL connection unexpectedly closed
  • Add properties to ArrayList<Object> in Java
  • Multiple Adapters or One Adapter for different lists and objects - Code Performance
  • Is it good practice in Java for a class's method to redundantly return a modified global field of the class?
  • How to change the color of the background in libgdx labels?
  • direct file path not working
  • ClassFileTransformer + Javassist: no such field
  • How do I change and instance variable for an object which the user selects from a combobox?
  • reading and updating a large xml file in java
  • ActionListener and Thread.sleep
  • What is the maximum of number of arguments for varargs in java?
  • When I compile I get an error as "ask" cannot be resolved or is not a field"
  • What is the best way to check if 4 integer variables are equal to 0?
  • Storing constant webdriver elements in an enum
  • Java: Why main class does not extend Thread class
  • Java - how to find out if a directory is being used by another process?
  • How can I get a method to print?
  • Java unknown exceptions
  • BufferedReader,StreamWriter crash
  • found raw type: JComboBox
  • Java Generics -> Function return type
  • how to refresh contents of jtable on event of action listener?
  • Why does List interface extend Collection interface?
  • Pros and Cons of Clojure http client libraries
  • use final inside a for each loop
  • Convert java data object to service object
  • Unsupported major.minor version 51.0 while executing JSP
  • How do I display a word diagonally in Java?
  • making sure one task completes before another starts in java
  • My program gives an index out of bounds error
  • Removing duplicate characters in a String (user inputted keyword)
  • Jersey 2.0 Content-Length not set
  • AWS.SimpleQueueService.NonExistentQueue Exception thrown when Accessing Existing SQS queue
  • Where can I find the source code for the com.sun.jdi package?
  • How can I get path of resource under WEB-INF/class folder (java ee web dynamic project)
  • convert a hexadecimal into a decimal via string convert in java
  • error populating a table using jstl
  • If Singletons are bad then how do you store global state for a framework
  • input system where the user inputs the array position of the object followed by a # to indiacte quantity but it gives me
  • Java: when would I ever want to use static methods when I can use a singleton instead?
  • Extracting RSA public key modulus and exponent stored in unsigned char arrays
  • What does "cannot be resolved to a type" mean, and how can I fix it? Java Android 4.0
  • How can I have a callback on stdout/stderr readiness instead of busy polling?
  • How to report AWT/Swing event queue length programmatically?
  • What is the difference between different for loops in Java?
  • Java arrays effective use/alternative
  • EasyMock chained method call producing null pointer exception
  • Installing Java on Windows 8
  • Java: Is it bad practice to write methods that start with "get" when they aren't getters?
  • Can Iterable.filter() skip processing with "constant" (including short circuited) Predicates?
  • How to save edited JTable data to database?
  • Java Packet Sniffer
  • I have a getText error
  • Reading bytestream and writing to file
  • dat file is not get created by buffered writer
  • Converting a pdf to word document using java
  • Measuring memory use of a piece of code at runtime in Java as an on-going functionality of a service
  • What is Matrix.frustumM(mProjMatrix, 0, -ratio, ratio, -1, 1, 3, 7); in OpenGL ES 20?
  • shadow
    Privacy Policy - Terms - Contact Us © ourworld-yourmove.org