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

   • 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())))

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     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>

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     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.

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     3/5

   • Generator functions equivalent in Java

     Top Answer

     Answered Mar 15, 2015 · 57 votes

     Had the same need so wrote a little class for it. Here are some examples:

     Generator<Integer> simpleGenerator = new Generator<Integer>() { public void run() throws InterruptedException { yield(1); // Some logic here... yield(2); }};for (Integer element : simpleGenerator) System.out.println(element);// Prints "1", then "2".

     Infinite generators are also possible:

     Generator<Integer> infiniteGenerator = new Generator<Integer>() { public void run() throws InterruptedException { while (true) yield(1); }};

     The Generator class internally works with a Thread to produce the items. By overriding finalize(), it ensures that no Threads stay around if the corresponding Generator is no longer used.

     The performance is obviously not great but not too shabby either. On my machine with a dual core i5 CPU @ 2.67 GHz, 1000 items can be produced in < 0.03s.

     The code is on GitHub. There, you'll also find instructions on how to include it as a Maven/Gradle dependency.

     Other Answers

     Answered Jul 14, 2014 · 26 votes

     Indeed Java has no yield, but you can now use Java 8 streams. IMO it's really a complicated iterator since it's backed by an array, not a function. Given it's a loop in a loop in a loop can be expressed as a Stream using filter (to skip the nulls) and flatMap to stream the inner collection. It's also about the size of the Python code. I've converted it to an iterator to use at your leisure and printed to demonstrate, but if all you were doing was printing, you could end the stream sequence with forEach(System.out::println) instead of iterator().

     public class ArrayIterate{ public static void main(String args[]) { Integer[][][] a = new Integer[][][] { { { 1, 2, null, 3 }, null, { 4 } }, null, { { 5 } } }; Iterator<Object> iterator = Arrays.stream(a) .filter(ax -> ax != null) .flatMap(ax -> Arrays.stream(ax) .filter(ay -> ay != null) .flatMap(ay -> Arrays.stream(ay) .filter(az -> az != null))) .iterator(); while (iterator.hasNext()) { System.out.println(iterator.next()); } }}

     I'm writing about implementation of generators as part of my blog on Java 8 Functional Programming and Lambda Expressions at http://thecannycoder.wordpress.com/ which might give you some more ideas for converting Python generator functions into Java equivalents.

     Other Answers

     Answered Jul 05, 2013 · 7 votes

     I wish Java had generator/yield, but since it doesn't using Iterators is probably your best bet.

     In this example I stuck with arrays, but in general I would advise using Iterable Collection instead, eg. List. In the example I show how it's pretty easy to get iterators for arrays though:

     package example.stackoverflow;-import com.sun.xml.internal.xsom.impl.scd.Iterators;-import java.util.Arrays;import java.util.Iterator;public class ArrayGenerator<T> implements Iterable<T> { private final T[][][] input; public ArrayGenerator(T[][][] input) { this.input = input; } @Override public Iterator<T> iterator() { return new Iter(); } private class Iter implements Iterator<T> { private Iterator<T[][]> x; private Iterator<T[]> y; private Iterator<T> z; { x = Arrays.asList(input).iterator(); y = Iterators.empty(); z = Iterators.empty(); } @Override public boolean hasNext() { return z.hasNext() || y.hasNext() || x.hasNext(); } @Override public T next() { while(! z.hasNext()) { while(! y.hasNext()) { y = Arrays.asList(x.next()).iterator(); } z = Arrays.asList(y.next()).iterator(); } return z.next(); } @Override public void remove() { throw new UnsupportedOperationException("remove not supported"); } } public static void main(String[] args) { for(Integer i : new ArrayGenerator<Integer>( new Integer[][][]{ { {1, 2, 3}, {4, 5} }, { {}, {6} }, { }, { {7, 8, 9, 10, 11} } } )) { System.out.print(i + ", "); } }}

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     4/5

   • 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));

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     5/5

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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 java.util.Dictionary class in Java is an abstract class that represents a collection of key-value pairs, where keys are unique and are used to access the values. It was part of the Java Collections Framework introduced in Java 1.2 but has been largely replaced by the java.util.Map interface since Java 1.2.

3. stackoverflow.com › questions › 18280373Iterate Dictionary in Java - Stack Overflow

   stackoverflow.com › questions › 18280373

   • Cached

   Aug 11, 2015 · java.util.Map is the Dictionary equvivalent and below is an example on how you can iterate through each entry. Map<String, Object> map = new HashMap<String, Object>(); //...

   Code sample

   for (Map.Entry<String, Object> entry : objects.entrySet()) {

     String key = entry.getKey();

     Object val = entry.getValue();

   }

   See more on stackoverflow

4. People also ask

   How to use dictionary class in Java?

   • To use the Dictionary class, we need to import the java.util.Dictionary package. The put () method inserts the key-value pair data into the Dictionary object. To retrieve the size, we use the size () method. The get () method retrieves the value of the corresponding key which is passed as a parameter.

   Dictionary in Java - Java Dictionary - Java Dictionary class - TutorialCup

   www.tutorialcup.com/java/dictionary-in-java.htm

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   What is a dictionary class?

   • The Dictionary class is the abstract parent of any class, such as Hashtable, which maps keys to values. Every key and every value is an object. In any one Dictionary object, every key is associated with at most one value. Given a Dictionary and a key, the associated element can be looked up.

   Dictionary (Java Platform SE 8 ) - docs.oracle.com

   docs.oracle.com/javase/8/docs//api/java/util/Dictionary.html

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   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/

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   How to store a value in a dictionary?

   • Given a key and value, you can store the value in a Dictionary object. Once the value is stored, you can retrieve it by using its key. Thus, like a map, a dictionary can be thought of as a list of key/value pairs. Following are the methods defined by Dictionary are listed below − Returns an enumeration of the values contained in the dictionary.

   Dictionary Methods in Java - Online Tutorials Library

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

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

   www.geeksforgeeks.org › dictionary-elements-method

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   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 ...

6. docs.oracle.com › javase › 8Uses of Class java.util.Dictionary (Java Platform SE 8 ) - Oracle

   docs.oracle.com › javase › 8

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   Contains the collections framework, legacy collection classes, event model, date and time facilities, internationalization, and miscellaneous utility classes (a string tokenizer, a random-number generator, and a bit array).

7. docs.oracle.com › api › javaDictionary (Java Platform SE 8 ) - Oracle

   docs.oracle.com › api › java

   • Cached

   The Dictionary class is the abstract parent of any class, such as Hashtable, which maps keys to values. Every key and every value is an object. In any one Dictionary object, every key is associated with at most one value. Given a Dictionary and a key, the associated element can be looked up.

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 · Dictionary Methods in Java. Java 8 Object Oriented Programming Programming. Dictionary is an abstract class that represents a key/value storage repository and operates much like Map. Given a key and value, you can store the value in a Dictionary object. Once the value is stored, you can retrieve it by using its key.

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

   ioflood.com › blog › java-dictionary

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   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.