logo
down
shadow

Get aggregated list of properties from list of Objects(Java 8)


Get aggregated list of properties from list of Objects(Java 8)

By : Daniel Segovia
Date : January 11 2021, 05:14 PM
Does that help I have a class Division which is having a list of Section as property as below , You may do it using the flatMap operator. Here's how it looks.
code :
List<Section> sections = divisions.stream()
    .flatMap(d -> d.getSections().stream())
    .collect(Collectors.toList());


Share : facebook icon twitter icon
Calling setter method of object in List also changes properties of other objects in List. List is value in HashMap

Calling setter method of object in List also changes properties of other objects in List. List is value in HashMap


By : Sanco de Voogd
Date : March 29 2020, 07:55 AM
This might help you The problem is in your randomlyExpand function. You are iterating trough your list of 5 distinguished objects that you have previously created with this:
code :
for(int i = 0; i < 5; i++){
    list2.add(new TestObject());
}
 int randomInt = ran.nextInt(values.size());
 tempList.add(values.get(randomInt));
for (int i = 0; i < 10; i++){
    int randomInt = ran.nextInt(values.size());

    TestObject obj = new TestObject();
    obj.setName(values.get(randomInt).getName());

    tempList.add(obj);
}
C# How to create a List of objects with read only properties by passing in a list of similar objects via constructor

C# How to create a List of objects with read only properties by passing in a list of similar objects via constructor


By : Patrick
Date : March 29 2020, 07:55 AM
hope this fix your issue My class is defined as follows. Without going too much into detail I don't want anyone to be able to alter this instantiated object, or the object that is passed in to this classes constructor. , Simply use LINQ and the current ctor:
code :
List<ItemDeliveryInfo> itemDeliveryInfos = 
          itemDeliveryAudits.Select(i => new ItemDeliveryInfo(i, true, false)).ToList();
Java 8 streaming: How to convert list of objects to a list of its selected properties

Java 8 streaming: How to convert list of objects to a list of its selected properties


By : bipopbipooop
Date : March 29 2020, 07:55 AM
this will help I have a class , How about something like this
code :
stream.stream().flatMap(p -> Stream.of(p.firstName, p.lastName)).collect(Collectors.toList());
Java - map object properties in one list to another list of objects

Java - map object properties in one list to another list of objects


By : user764611
Date : March 29 2020, 07:55 AM
it fixes the issue As I said in the comments, I'd suggest that you rethink your model a bit. First introduce a Shop class:
code :
public class Shop {
    private final String id; // Id of this shop.
    private final ShopOwner owner; // Owner of this shop.
    public Shop(String id, ShopOwner owner) {
        this.id = id;
        this.owner = owner;
    }
    public String getId() { return id; }

    // Overwrite equals and hashcode to allow using Shop as a key in a HashMap (only necessary if you want to enforce uniqueness of a ShopOwner's shops by maintaining a ShopOwner's owned shops using a Map).
    // We simply define equality based on id equality and rely on String.hashCode() (note that this will have to be changed if you want to add additional properties and define equality based on those):
    @Override
    public boolean equals(Object o) {
        return o instanceof Shop && o.toString().equals(this.toString());
    }

    @Override
    public int hashCode() {
        return toString().hashCode();
    }
    @Override
    public String toString() {
        return id;
    }
    // Other properties etc.
}
public class ShopOwner {
   String owner;
   List<Shop> shops = new ArrayList<>(); // Shops owned by this ShopOwner.
   int age;     
   String dateOfBirth;
   public void addShop(Shop s) {
       // Note that this does NOT guarantee uniqueness of shops if your DB query returns multiple instances of the same shop.
       // If you want this, you could use a Map instead.
       this.shops.add(s);
   }
   // Your other getters etc.
}
List<ShopOwnerMap> soms = ...; // the list you produced from the DB query.
List<ShopOwner> sos = ...; // your list of ShopOwners, each of which needs to be initialized with the shops they own, i.e. their initial lists of shops are empty.
// Note that the below could be reduced from O(N^2) to O(N) if you manage your ShopOwners using a Map (using an equals+hashCode scheme as suggested for Shop).
for (ShopOwnerMap som : soms) {
    for (ShopOwner so : sos) {
        // We assume that the 'owner' property (perhaps 'name' is more suitable?) is unique among ShopOwners.
        if (som.getOwner().equals(so.getOwner()) {
            // Found the corresponding shop owner; create shop instance and add to list of owned shops.
            so.addShop(new Shop(som.getShopId(), so));
        }
    }
}
How to Compare a List of Objects and Their Properties, then Update the Original List in Java

How to Compare a List of Objects and Their Properties, then Update the Original List in Java


By : eDube
Date : March 29 2020, 07:55 AM
I wish this helpful for you I have an object that has a list as its property, e.g. , This works:
code :
package collection.delta;

import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.function.Predicate;
import java.util.stream.Collectors;

import collection.delta.model.A;
import collection.delta.model.B;

public class App {
    public static void main( String[] args ) {

        List<A> originalA = new ArrayList<A>();
        List<A> newA = new ArrayList<A>();

        List<B> bListOriginalA1 = new ArrayList<B>();
        bListOriginalA1.add(new B("originalA1_B1"));
        bListOriginalA1.add(new B("originalA1_B2"));
        bListOriginalA1.add(new B("originalA1_B3"));
        bListOriginalA1.add(new B("originalA1_B4"));

        A originalA1 = new A("originalA1", bListOriginalA1);

        List<B> bListOriginalA2 = new ArrayList<B>();
        bListOriginalA2.add(new B("originalA2_B1"));
        bListOriginalA2.add(new B("originalA2_B2"));
        bListOriginalA2.add(new B("originalA2_B3"));
        bListOriginalA2.add(new B("originalA2_B4"));

        A originalA2 = new A("originalA2", bListOriginalA2);

        List<B> bListOriginalA3 = new ArrayList<B>();
        bListOriginalA3.add(new B("originalA3_B1"));
        bListOriginalA3.add(new B("originalA3_B2"));
        bListOriginalA3.add(new B("originalA3_B3"));
        bListOriginalA3.add(new B("originalA3_B4"));

        A originalA3 = new A("originalA3", bListOriginalA3);

        originalA.add(originalA1);
        originalA.add(originalA2);
        originalA.add(originalA3);


        List<B> bListNewA1 = new ArrayList<B>();
        bListNewA1.add(new B("originalA1_B1"));
        bListNewA1.add(new B("originalA1_B2"));
        bListNewA1.add(new B("originalA1_B3"));
        bListNewA1.add(new B("originalA1_B4"));

        A newA1 = new A("originalA1", bListNewA1);

        List<B> bListNewA2 = new ArrayList<B>();
        bListNewA2.add(new B("originalA2_B1"));
        bListNewA2.add(new B("originalA2_B3"));
        bListNewA2.add(new B("originalA2_B4"));
        bListNewA2.add(new B("originalA2_B2"));

        A newA2 = new A("originalA2", bListNewA2);

        List<B> bListNewA3 = new ArrayList<B>();
        bListNewA3.add(new B("originalA3_B1"));
        bListNewA3.add(new B("originalA3_B2"));
        bListNewA3.add(new B("originalA3_B5"));
        bListNewA3.add(new B("originalA3_B4"));

        A newA3 = new A("originalA3", bListNewA3);

        List<B> bListNewA4 = new ArrayList<B>();
        bListNewA4.add(new B("A4_B1"));
        bListNewA4.add(new B("A4_B2"));
        bListNewA4.add(new B("A4_B3"));
        bListNewA4.add(new B("A4_B4"));

        A newA4 = new A("originalA4", bListNewA4);

        newA.add(newA1);
        newA.add(newA2);
        newA.add(newA3);
        newA.add(newA4);

        List<A> result = newA.stream()
                .filter(not(new HashSet<A>(originalA)::contains))
                .collect(Collectors.toList());

        A tempA = null;
        B tempB = null;
        List<B> bList = null;
        for (A a : result) {
            if (!containsName(originalA, a.getaName())) {
                originalA.add(a);
            } else {
                tempA = getAIfPresent(originalA, a.getaName());

                if (tempA != null) {

                    bList = a.getbList().stream()
                            .filter(not(new HashSet<B>(tempA.getbList())::contains))
                            .collect(Collectors.toList());

                    if (bList != null) {
                        tempA.getbList().addAll(bList);
                    }
                }
            }
        }

        System.out.println("");
    }

    public static <T> Predicate<T> not(Predicate<T> predicate) {
        return predicate.negate();
    }

    public static boolean containsName(final List<A> list, final String name){
        return list.stream().map(A::getaName).filter(name::equals).findFirst().isPresent();
    }

    public static A getAIfPresent(final List<A> list, final String name) {
        return list.stream().filter(x -> x.getaName().equalsIgnoreCase(name)).findFirst().orElse(null);
    }

}
Related Posts Related Posts :
  • Android Broadcastreceiver for other apps install/delete not working
  • Android Studio onClick not working in BindViewHolder
  • How to use Spring Converter for some controllers only?
  • How verify that 3 numbers in sequence are equals?
  • When using .compareTo to compare dates, why doesn't it take Months into account?
  • Does the perfomance of "filter then map" and "map then filter" differ in a Stream?
  • How can I set the initial Delay after pressing the start Button to a specific time (HH:mm:ss) format
  • How to switch between Android devices during the tests
  • How to configure java.util.logging via properties to use standard output?
  • How to iterate through array in order
  • Is there better way of iteration to find the evenly divisible number?
  • How to split a string to non empty words if it might include a separator like tab on first place
  • Supplier<Sequence<String>> cannot be iterated more than once
  • Why there is only one thread can actually started in @PostConstruct method?
  • Manage CompletionStage inside of Netty handler
  • Url Problem while Developing on Localhost and deploy on Remote Virtual Server
  • How to identify the missing type id in Jackson error?
  • android data binding error: cannot find symbol
  • Spring Boot application with a jar dependency does not run after maven build
  • Spring Data JPA query , filter ? search engine ? JPQL?
  • Why LiveData returns null in ViewModel?
  • what this line of code mean....new URLClassLoader(new URL[0],getClass().getClassLoader());
  • Why do need to use new Random() instead of just Random Randomnum?
  • I want to access zk components from the java file
  • How do I cast FieldValue.serverTimestamp() to Kotlin/Java Date Class
  • Insertion Sort Double Array with User Input - JAVA
  • Creating 2 dimesional array with user input and find sum of specific columns
  • can not get Advertising ID Provider in android
  • Convert list of Objects to map of properties
  • How to represent an undirected weighted graph in java
  • Return values as array from collection
  • ByteBuddy generic method return cast to concrete type
  • ImageView hides the round corners of the parent
  • Is there a way to find setter method by its getter method or vice versa in a class?
  • Unable to find a document in Mongodb where exact date match in java
  • UsernamePasswordAuthenticationFilter skips success handler
  • Use Java filter on stream with in a stream filter
  • Default Login not successful in spring boot 2.1.7
  • Adding key value pairs from a file to a Hashmap
  • Rub regex: matching a char except when after by another char
  • Convert Base64 String to String Array
  • Escape Unicode Character 'POPCORN' to HTML Entity
  • An empty JSON field which is a boolean/nullable field in Java model, is getting converted as null
  • Mongo java driver cannot find public constructor for interface
  • How to unit test writing a file to AWS Lambda output stream?
  • How to make a GitHub GraphQL API Call from Java
  • What's the difference between @ComponentScan and @Bean in a context configuration?
  • Expected class or package adding a view using a class
  • can be delete of a element in a static array be O(1)?
  • Instance variable heap or stack ? ( with specific example)
  • Assert progress of ProgressBar in Espresso test
  • How to detect if gson.fromjson() has excess elements
  • I cant generate the proper code to select the a specific filter on a BI dashboard I am working on
  • How to Inject Dependencies into a Servlet Filter with Spring Boot Filter Registration Bean?
  • Thrift types as a Generic
  • Effective algorithm to random 4 unique integers less than a big max such as 100_000
  • Combining or and negation in Java regex?
  • Unable to instantiate default tuplizer Exception
  • Multi-tenant migration to work with quarkus
  • Ignite persisting a Set: Cannot find metadata for object with compact footer
  • shadow
    Privacy Policy - Terms - Contact Us © festivalmusicasacra.org