Yahoo Web Search

Search results

1. Top results related to 8 functions of dictionary in java code list

   • List of objects to map in java 8

     Top Answer

     Answered Feb 12, 2018 · 21 votes

     yourTypes.stream() .collect(Collectors.groupingBy( ObjectA::getType, Collectors.mapping( ObjectA::getId, Collectors.toList())))

     Check all answers on Stack Overflow

     1/5

   • Java 8 Stream filtering value of list in a list

     Top Answer

     Answered Jan 07, 2015 · 20 votes

     You can do:

     myObjects.stream() .filter(t -> t.getType().equals(someotherType) && t.getSubTypes().stream().anyMatch(<predicate>)) .collect(Collectors.toList());-

     This will fetch all the MyObject objects which

     • meet a criteria regarding the type member.
     • contain objects in the nested List<String> that meet some other criteria, represented with <predicate>

     Check all answers on Stack Overflow

     2/5

   • Dictionary of ArrayLists in Java

     Top Answer

     Answered Jun 05, 2012 · 2 votes

     Instead of ArrayList grades; you'd have to use ArrayList grades = new ArrayList();

     Yet better: ArrayList<Float> grades = new ArrayList<Float>(); //or use Double or Number

     Note that unlike C or C++ creating a variable doesn't create the object as well. In C++ you could imagine your code as ArrayList* grades; i.e. you'd just create the reference/pointer here.

     Additional thoughts:

     • Dictionary studentGrades; this will be initialized to null.
     • public void main(String[] args) that's not a valid main function since it would have to be static
     • if you have a public static void main(String[] args) you can't use this since you don't have an object instance in the static context
     • You can't instantiate Dictionary since it is abstract. Use one of its subclasses, e.g. new Hashtable<String, List<Float>>(), or a map, e.g. Map<String, List<Float> dictionary = new HashMap<String, List<Float>>();
     • Note that local primitive variables are also not initialized, so this could give you an error too: boolean res; In Java only class members are initialized, local variables are not.

     Check all answers on Stack Overflow

     3/5

   • List all index of all characters in a string in Java 8

     Top Answer

     Answered Dec 17, 2021 · 2 votes

     A neat trick you can use is to stream the indices of the string, and then collect them by the character at that index:

     Map<Character, List<Integer>> indices = IntStream.range(0, input.length()) .boxed() .collect(Collectors.groupingBy(input::charAt));

     Check all answers on Stack Overflow

     4/5

   • Java 8 - How to sum all List element in a Map of Lists

     Top Answer

     Answered Feb 03, 2015 · 9 votes

     You have to be aware that you can combine Collectors. See Collectors.groupingBy(Function,Collector)

     Map<Integer, Integer> byId=risks.stream.collect( Collectors.groupingBy(Risk::getId, Collectors.summingInt(Risk::getRiskValue)));-

     You can also combine it with the first operation:

     Map<Integer, Integer> byId=results.stream().map(Risk::new).collect( Collectors.groupingBy(Risk::getId, Collectors.summingInt(Risk::getRiskValue)));

     Note that I assume that you have a method getRiskValue() in your class Risk, otherwise you have to replace Risk::getRiskValue with a lambda expression r -> r.riskValue to access the field, however, having getter methods is always recommended.

     The result maps from id to total.

     After reading your question again, I noticed that you actually want to sum up riskValue and store it within totRisk of each (?) Risk instance. This is a bit more complicated as it doesn’t fit the common usage pattern:

     Map<Integer, List<Risk>> byId=results.stream().map(Risk::new).collect( Collectors.groupingBy(Risk::getId, Collectors.collectingAndThen( Collectors.toList(), l-> { int total=l.stream().collect(Collectors.summingInt(r -> r.riskValue)); l.forEach(r->r.totRisk=total); return l; })));

     at this point we really should switch to using import static java.util.stream.Collectors.*;:

     Map<Integer, List<Risk>> byId=results.stream().map(Risk::new).collect( groupingBy(Risk::getId, collectingAndThen(toList(), l-> { int total=l.stream().collect(summingInt(r -> r.riskValue)); l.forEach(r->r.totRisk=total); return l; })));

     Check all answers on Stack Overflow

     5/5

   Show moreShow less

2. www.geeksforgeeks.org › java-util-dictionary-classJava.util.Dictionary Class in Java - GeeksforGeeks

   www.geeksforgeeks.org › java-util-dictionary-class

   • Cached

   Apr 9, 2023 · The Dictionary class defines the following methods: get (Object key): Returns the value associated with the specified key in the dictionary, or null if the key is not found. put (Object key, Object value): Inserts a key-value pair into the dictionary. If the key already exists, its corresponding value is.

3. www.geeksforgeeks.org › dictionary-elements-methodDictionary elements() Method in Java with Examples

   www.geeksforgeeks.org › dictionary-elements-method

   • Cached

   Dec 27, 2018 · The keys () method of Dictionary class in Java is used to get the enumeration of the values present in the dictionary. Syntax: Enumeration enu = DICTIONARY.elements() Parameters: The method does not take any parameters. Return value: The method returns an enumeration of the values of the Dictionary. Below programs are used to illustrate the ...

4. People also ask

   What is a dictionary in Java?

   • Dictionary () Sole constructor. The java.util.Dictionary class is a class in Java that provides a key-value data structure, similar to the Map interface. It was part of the original Java Collections framework and was introduced in Java 1.0. However, the Dictionary class has since been considered obsolete and its use is generally discouraged.

   Java.util.Dictionary Class in Java - GeeksforGeeks

   www.geeksforgeeks.org/java-util-dictionary-class-java/

   See all results for this question

   How to organize a dictionary in Java?

   • Addressing an element of the dictionary, deleting, searching in the dictionary is performed by the key. It seems convenient to organize using such data structure, for example, a telephone book, where the name (key) corresponds to the phone number (value). To begin with, java.util.Dictionary util.Dictionary is an abstract class.

   How to create a dictionary in Java - CodeGym

   codegym.cc/groups/posts/how-to-create-a-dictionary-in-java

   See all results for this question

   How to get enumeration of a dictionary in Java?

   • The keys () method of Dictionary class in Java is used to get the enumeration of the values present in the dictionary. Syntax: Parameters: The method does not take any parameters. Return value: The method returns an enumeration of the values of the Dictionary. Program 2: A Computer Science portal for geeks.

   Dictionary elements() Method in Java with Examples

   www.geeksforgeeks.org/dictionary-elements-method-in-java-with-examples/

   See all results for this question

   How do dictionaries work in Java?

   • To truly grasp the working of Java dictionaries, it’s essential to understand the concept of hashing. Hashing is a process that takes an input (or ‘message’) and returns a fixed-size string of bytes, typically in the form of a ‘hash code’.

   Java Dictionary | Hashmaps and Hashtables Guide

   ioflood.com/blog/java-dictionary/

   See all results for this question

5. stackoverflow.com › questions › 1145175What's the most practical way to have "functions in a ...

   stackoverflow.com › questions › 1145175

   • Cached

   Jul 19, 2013 · When programming with C/C++ or Python I sometimes used to have a dictionary with references to functions according to the specified keys. However, I don't really know how to have the same -- or at the very least similar -- behavior in Java allowing me dynamic key-function (or method, in Java slang) association.

   Code sample

   private static Map<String, Action<Foo>> getActions() {

     Action<Foo> firstAction = new Action<Foo>() {

     @Override public void execute(Foo item) {

     }

     };...

   See more on stackoverflow

6. ioflood.com › blog › java-dictionaryJava Dictionary | Hashmaps and Hashtables Guide

   ioflood.com › blog › java-dictionary

   • Cached

   Nov 9, 2023 · Think of Java’s HashMaps and Hashtables as a real-world dictionary, allowing us to store and retrieve data based on unique keys. These tools are incredibly versatile and handy for various tasks. This guide will walk you through the creation, usage, and manipulation of dictionaries in Java.

7. codegym.cc › how-to-create-a-dictionary-in-javaHow to create a dictionary in Java - CodeGym

   codegym.cc › how-to-create-a-dictionary-in-java

   • Cached

   Jan 12, 2022 · To begin with, java.util.Dictionary <K, V> util.Dictionary is an abstract class. It represents a key-value relation and works similar to a map. Given a key you can store values and when needed can retrieve the value back using its key. Thus, it is a list of key-value pair. Since this class is abstract, we won’t work with it directly.

   • Occupation: Java Engineer at Playtika

8. www.tutorialspoint.com › dictionary-methods-in-javaDictionary Methods in Java - Online Tutorials Library

   www.tutorialspoint.com › dictionary-methods-in-java

   • Cached

   Sep 24, 2019 · Following is an example implementing put() and get() method of the Dictionary class −. Example import java.util.*; public class Demo { public static void main(String[] args) { Dictionary dictionary = new Hashtable(); dictionary.put("20", "John"); dictionary.put("40", "Tom"); dictionary.put("60", "Steve"); dictionary.put("80", "Kevin ...

9. thelinuxcode.com › create-a-dictionary-in-javaThe Complete Guide to Effectively Using Dictionaries in Java

   thelinuxcode.com › create-a-dictionary-in-java

   • Cached

   Dec 27, 2023 · Dictionaries are a fundamental data structure in programming used to map keys to values for efficient lookup and organization. Mastering dictionaries is key to writing optimized Java code. In this comprehensive guide, you‘ll learn all about dictionaries and how to leverage them in your Java programs like a pro! We‘ll cover: What dictionaries are and … The Complete Guide to Effectively ...