Java generate all pairs

Class KeyPairGenerator

The KeyPairGenerator class is used to generate pairs of public and private keys. Key pair generators are constructed using the getInstance factory methods (static methods that return instances of a given class).

A Key pair generator for a particular algorithm creates a public/private key pair that can be used with this algorithm. It also associates algorithm-specific parameters with each of the generated keys.

• Algorithm-Independent Initialization All key pair generators share the concepts of a keysize and a source of randomness. The keysize is interpreted differently for different algorithms (e.g., in the case of the DSA algorithm, the keysize corresponds to the length of the modulus). There is an initialize method in this KeyPairGenerator class that takes these two universally shared types of arguments. There is also one that takes just a keysize argument, and uses the SecureRandom implementation of the highest-priority installed provider as the source of randomness. (If none of the installed providers supply an implementation of SecureRandom , a system-provided source of randomness is used.) Since no other parameters are specified when you call the above algorithm-independent initialize methods, it is up to the provider what to do about the algorithm-specific parameters (if any) to be associated with each of the keys. If the algorithm is the DSA algorithm, and the keysize (modulus size) is 512, 768, 1024, or 2048, then the Sun provider uses a set of precomputed values for the p , q , and g parameters. If the modulus size is not one of the above values, the Sun provider creates a new set of parameters. Other providers might have precomputed parameter sets for more than just the modulus sizes mentioned above. Still others might not have a list of precomputed parameters at all and instead always create new parameter sets.
• Algorithm-Specific Initialization For situations where a set of algorithm-specific parameters already exists (e.g., so-called community parameters in DSA), there are two initialize methods that have an AlgorithmParameterSpec argument. One also has a SecureRandom argument, while the other uses the SecureRandom implementation of the highest-priority installed provider as the source of randomness. (If none of the installed providers supply an implementation of SecureRandom , a system-provided source of randomness is used.)

In case the client does not explicitly initialize the KeyPairGenerator (via a call to an initialize method), each provider must supply (and document) a default initialization. See the Keysize Restriction sections of the JDK Providers document for information on the KeyPairGenerator defaults used by JDK providers. However, note that defaults may vary across different providers. Additionally, the default value for a provider may change in a future version. Therefore, it is recommended to explicitly initialize the KeyPairGenerator instead of relying on provider-specific defaults.

Note that this class is abstract and extends from KeyPairGeneratorSpi for historical reasons. Application developers should only take notice of the methods defined in this KeyPairGenerator class; all the methods in the superclass are intended for cryptographic service providers who wish to supply their own implementations of key pair generators.

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Java Tutorial: Generating a List of Pairs

Solution: You use a native query, it seem that there is no list parameter at all for native queries: Set list parameter to native query How to use a dynamic parameter in a IN clause of a JPA named query? If you are using Eclipse IDE to run Pair Class in JavaTuples, then Right Click Project ->Properties ->Java Build Path ->Add External Jars and upload the downloaded JavaTuples jar file.

How in JPA create list of pairs as parameter?

When employing a native query, it appears that there is a lack of any list parameter.

Set list parameter to native query

What is the proper way to incorporate a dynamic parameter into the IN clause of a JPA named query?

The SQL concatenation needs to be done manually.

Creating a list of pairs in java, Then of course make a List using this new class, e.g.: List pairList = new ArrayList (); You can also always make a List s of List s, but it becomes difficult to enforce sizing (that you have only pairs) and you would be required, as with arrays, to have consistent typing. Share. Usage exampleList pairList = new ArrayList();Feedback

List to Map of Pairs in Java

By providing both Collector and groupingBy , you can generate the inner map using static import of Collectors.groupingBy and Collectors.toMap .

results.stream() .collect(groupingBy(MyClass::getName, toMap(MyClass::getAction,MyClass::getPrice))); 

To achieve the desired outcome, it is essential to handle them in a comprehensive and error-free manner. Here’s an organized and easily understandable approach to accomplish this.

 public class Builder < public static void main(String[] args) throws IOException < Listlist = Arrays.asList(new MyClass("AAA", "action1", 5) , new MyClass("BBB", "action13", 7), new MyClass("AAA", "action31", 2)); Map> listList = new HashMap>(); list.stream().map(l -> < Listpairs = listList.getOrDefault(l.name, new ArrayList<>()); pairs.add(new Pairs(l.action, l.price)); listList.put(l.name, pairs); return pairs; >).collect(Collectors.toList()); System.out.println(listList); // , Pairs], BBB=[Pairs]> > > class Pairs < String action; int price; public Pairs(String action, int price) < this.action = action; this.price = price; >@Override public String toString() < final StringBuilder sb = new StringBuilder("Pairs<"); sb.append("action='").append(action).append('\''); sb.append(", price=").append(price); sb.append('>'); return sb.toString(); > > class MyClass < String name; String action; int price = 5; public MyClass(String name, String action, int price) < this.name = name; this.action = action; this.price = price; >> 

To make it easier to handle, I propose utilizing a Map> map.

Here an idea how it can be coded.

import java.util.*; public class MyClass < String name; String action; int price; public MyClass(String name, String action, int price) < this.name = name; this.action = action; this.price = price; >@Override public String toString() < return ""; > public static void main(String[] args) < Map> map = new HashMap<>(); MyClass[] objs = < new MyClass("AAA", "action1", 5), new MyClass("BBB", "action2", 7), new MyClass("AAA", "action3", 2) >; for(MyClass myClass: objs) < if(!map.containsKey(myClass.name)) < map.put(myClass.name, new ArrayList()); > map.get(myClass.name).add(myClass); > System.out.println(map); > > 

Pair Class in Java, JavaFX 2.2 has the javafx.util.Pair class which can be used to store a pair. We need to store the values into Pair using the parameterized constructor …

Creating all pairs of list of values in hadoop

The reducer receives the complete data, which is actually stored on the disk. The data is loaded into memory as you iterate through the Iterable of values. The returned object is reused for each value, with the fields and other state being replaced before it is provided to you.

To ensure all value objects are present in memory simultaneously, it is necessary to make a deliberate copy of the value object.

Upon reviewing your code, it appears that you are not storing the item pairs in memory. However, since you are directly outputting the item pairs, this should not be an issue.

A Java collection of value pairs? (tuples?), In Java 9, you can simply write: Map.entry (key, value) to create an immutable pair. Note: this method does not allow keys or values to be null. If you …

Create Pair Tuple from List in Java

Employ the fromCollection() function to generate a Pair Tuple using a List as the collection source.

Before proceeding, it’s necessary to identify the requirements for utilizing JavaTuples. To make use of pair class in javatuples, the subsequent package should be imported.

To utilize JavaTuples, you can follow these instructions for downloading and running the program. For Eclipse IDE users running the Pair Class, simply right click on the project, select «Properties», go to «Java Build Path», and then add the JavaTuples jar file as an external JAR.

The following is an example −

Example

import org.javatuples.Pair; import java.util.*; public class Demo < public static void main(String[] args) < List < String >myList = new ArrayList < String >(); myList.add("Summers!"); myList.add("Winters!"); Pair < String, String >p = Pair.fromCollection(myList); System.out.println("Result = " + p); > >

Output

How to store an array of pairs in Java?, I am new to Java, I want to store an array of pair of doubles. My code looks like this: import java.util.ArrayList; import java.util.Map.Entry; …

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🧮 Pairwise combinations generator with constraints for Java

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pavelicii/allpairs4j

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README.md

AllPairs4J is an open source Java library for generation of minimal set of test combinations.

AllPairs4J is a Java port of allpairspy project (with some improvements and bugfixes) developed by MetaCommunications Engineering and Tsuyoshi Hombashi.

In computer science, all-pairs testing or pairwise testing is a combinatorial method of software testing that, for each pair of input parameters to a system, tests all possible discrete combinations of those parameters. For example, if you want to create a test suite for browser testing, the domain can be described by the following parameters:

Browser: Chrome, Firefox, Safari, Edge OS: Windows, Linux, macOS RAM: 1024, 2048, 4096, 8192, 16384 Drive: HDD, SSD 

There are hundreds of possible combinations of these values. Instead of spending unreasonable amount of time testing them all, pairwise suggests testing all possible pairs of values. For example, is one pair, is another; together they represent a test case that covers many pairs: . In the end, you have good coverage while the number of test cases remains manageable.

With AllPairs4J, you are also able to add limitations on the domain to restrict generation of certain pairs. For example, specify that Safari can only be paired with macOS , and Edge can only be paired with Windows .

For more info on pairwise testing see https://www.pairwise.org/.

• Specify constraints to add limitations on the test combinations generation.
• Generate pairwise, triplewise, n-wise test combinations.
• Integrate with any Java project. There are pairwise tools that can sometimes be faster or generate smaller set covering all the test combinations (pict is probably your best choice). However, they are missing features mentioned above and/or do not integrate with Java.

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Java Program to Generate All Pairs of Subsets Whose Union Make the Set

This is a java program to generate and print all the pair of subsets whose union makes the original set.

Here is the source code of the Java Program to Generate All Pairs of Subsets Whose Union Make the Set. The Java program is successfully compiled and run on a Windows system. The program output is also shown below.

//This is a java program to generate all pair of subsets whose union results the original set import java.util.Random; import java.util.Scanner; public class Pair_Subset_Union_Set < public static int[] binary(int N) < int[] binary = new int[(int) Math.pow(2, N)]; for (int i = 0; i < Math.pow(2, N); i++) < int b = 1; binary[i] = 0; int num = i; while (num >0) < binary[i] += (num % 2) * b; num /= 2; b = b * 10; >> return binary; > public static void main(String args[]) < Random random = new Random(); Scanner sc = new Scanner(System.in); System.out.println("Enter the number of elements in the set: "); int N = sc.nextInt(); int[] sequence = new int[N]; for (int i = 0; i < N; i++) sequence[i] = Math.abs(random.nextInt(100)); System.out.println("The elements in the set : "); for (int i = 0; i < N; i++) System.out.print(sequence[i] + " "); int[] mask = new int[(int) Math.pow(2, N)]; mask = binary(N); System.out .println("\nThe pair of permutations whose union is original set are: "); for (int i = 0; i < (Math.pow(2, N) / 2); i++) < System.out.print("< "); for (int j = 0; j < N; j++) < if (mask[i] % 10 == 1) System.out.print(sequence[j] + " "); mask[i] /= 10; >System.out.print("> and "); System.out.print(" < "); for (int j = 0; j < N; j++) < if (mask[(int) Math.pow(2, N) - 1 - i] % 10 == 1) System.out.print(sequence[j] + " "); mask[(int) Math.pow(2, N) - 1 - i] /= 10; >System.out.println(">"); > sc.close(); > >

$ javac Pair_Subset_Union_Set.java $ java Pair_Subset_Union_Set Enter the number of elements in the set: 5 The elements in the set : 3 47 97 79 8 The pair of permutations whose union is original set are: < >and < 3 47 97 79 8 > < 3 >and < 47 97 79 8 > < 47 >and < 3 97 79 8 > < 3 47 >and < 97 79 8 > < 97 >and < 3 47 79 8 > < 3 97 >and < 47 79 8 > < 47 97 >and < 3 79 8 > < 3 47 97 >and < 79 8 > < 79 >and < 3 47 97 8 > < 3 79 >and < 47 97 8 > < 47 79 >and < 3 97 8 > < 3 47 79 >and < 97 8 > < 97 79 >and < 3 47 8 > < 3 97 79 >and < 47 8 > < 47 97 79 >and < 3 8 > < 3 47 97 79 >and < 8 >Enter the number of elements in the set: 3 The elements in the set : 37 76 87 The pair of permutations whose union is original set are: < >and < 37 76 87 > < 37 >and < 76 87 > < 76 >and < 37 87 > < 37 76 >and

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