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Codity Test and results

1) A non-empty array A consisting of N integers is given. The array contains an odd number of elements, and each element of the array can be paired with another element that has the same value, except for one element that is left unpaired. For example, in array A such that:   A[0] = 9  A[1] = 3  A[2] = 9   A[3] = 3  A[4] = 9  A[5] = 7   A[6] = 9 the elements at indexes 0 and 2 have value 9, the elements at indexes 1 and 3 have value 3, the elements at indexes 4 and 6 have value 9, the element at index 5 has value 7 and is unpaired. Write a function: class Solution { public int solution(int[] A); } that, given an array A consisting of N integers fulfilling the above conditions, returns the value of the unpaired element. For example, given array A such that:   A[0] = 9  A[1] = 3  A[2] = 9 A[3] = 3  A[4] = 9  A[5] = 7   A[6] = 9     the function should return 7, as explained in the example above. Write an efficient algorithm for the following assumptions: N
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StringJoiner

package java8examples; import java.util.Arrays; import java.util.List; import java.util.StringJoiner; import java.util.stream.Collectors; public class StringJoinerExp { public static void main (String args[]){ StringJoiner sj = new StringJoiner("/", "prefix-", "-suffix");         sj.add("2016");         sj.add("02");         sj.add("26");         String result = sj.toString(); //prefix-2016/02/26-suffix         System.out.println(" result : "+result);                        // StringJoiner is used internally by static String.join().         String result1 = String.join("-", "2015", "10", "31" );         System.out.println("StringJoiner  result1 : "+result1);                 // Collectors.joining         // Join List<String> example.         List<String> list = Arrays.asList("java", "python", "nodejs&quo
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What is Stream?

What is Stream? Stream represents a sequence of objects from a source, which supports aggregate operations. Following are the characteristics of a Stream − Sequence of elements  − A stream provides a set of elements of specific type in a sequential manner. A stream gets/computes elements on demand. It never stores the elements. Source  − Stream takes Collections, Arrays, or I/O resources as input source. Aggregate operations  − Stream supports aggregate operations like filter, map, limit, reduce, find, match, and so on. Pipelining  − Most of the stream operations return stream itself so that their result can be pipelined. These operations are called intermediate operations and their function is to take input, process them, and return output to the target. collect() method is a terminal operation which is normally present at the end of the pipelining operation to mark the end of the stream. Automatic iterations  − Stream operations do the iterations internally over th
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journaldev.com/3531/spring-mvc-hibernate-mysql-integration-crud-example-tutorial

journaldev.com/3531/spring-mvc-hibernate-mysql-integration-crud-example-tutorial
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Wildcard in Java Generics

he ? (question mark) symbol represents the wildcard element. It means any type. If we write <? extends Number>, it means any child class of Number, e.g., Integer, Float, and double. Now we can call the method of Number class through any child class object. We can use a wildcard as a  type of a parameter, field, return type, or local variable. However, it is not allowed to use a wildcard as a type argument for a generic method invocation, a generic class instance creation, or a supertype . Let's understand it by the example given below: import  java.util.*;   abstract   class  Shape{   abstract   void  draw();   }   class  Rectangle  extends  Shape{   void  draw(){System.out.println( "drawing rectangle" );}   }   class  Circle  extends  Shape{   void  draw(){System.out.println( "drawing circle" );}   }   class  GenericTest{   //creating a method that accepts only child class of Shape    public   static   void  drawShapes(List<?  e
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Generics In Java:

Generics In Java: Java Generics programming is introduced in J2SE 5 to deal with type-safe objects. It makes the code stable by detecting the bugs at compile time. Before generics, we can store any type of objects in the collection, i.e., non-generic. Now generics force the java programmer to store a specific type of objects. Advantage of Java Generics: There are mainly 3 advantages of generics. They are as follows: 1) Type-safety:   We can hold only a single type of objects in generics. It doesn?t allow to store other objects. Without Generics, we can store any type of objects. List list = new ArrayList();    list.add(10);  list.add("10");  With Generics, it is required to specify the type of object we need to store.  List<Integer> list = new ArrayList<Integer>();    list.add(10);  list.add("10");// compile-time error  2) Type casting is not required: There is no need to typecast the object. Before Generics, w
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Sorting Using Comparator

package java8examples; import java.math.BigDecimal; //import java.math.BigDecimal; import java.util.ArrayList; import java.util.Collections; import java.util.Comparator; import java.util.List; public class TestSorting { public static void main(String[] args) { List<Developer> listDevs = getDevelopers(); System.out.println("Before Sort"); for (Developer developer : listDevs) { System.out.println("ID : "+developer.getId()+" DEV Name : "+developer.getName()); } //sort by age Collections.sort(listDevs, new Comparator<Developer>() { @Override public int compare(Developer o1, Developer o2) { return o1.getId() - o2.getId(); } }); System.out.println("After Sort"); for (Developer developer : listDevs) { System.out.println("ID : "+developer.getId()+" DEV Name : "+developer.getName()); } } private static List<Developer> getDevelopers() {
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