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Articles on Trending Technologies
Technical articles with clear explanations and examples
StringJoiner add() method in Java 8
The add() method of the StringJoiner class is used in Java 8 to add a copy of the given CharSequence value as the next element of the StringJoiner value. If the new element ele is null, then the value null gets added.The syntax is as follows −public StringJoiner add(CharSequence ele)Here, the parameter ele is the element to be added, whereas, CharSequence is a readable sequence of char values.To work with the StringJoiner in Java 8, import the following package −import java.util.StringJoiner;We will first create a StringJoiner and set the delimeter −StringJoiner strJoin = new StringJoiner(", ")Use the add() method to ...
Read MoreCan we extend interfaces in Java? Explain?
An interface in Java is similar to class but, it contains only abstract methods and fields which are final and static.Just like classes you can extend one interface from another using the extends keyword as shown below −interface ArithmeticCalculations{ public abstract int addition(int a, int b); public abstract int subtraction(int a, int b); } interface MathCalculations extends ArithmeticCalculations{ public abstract double squareRoot(int a); public abstract double powerOf(int a, int b); }But, when you implement the sub-class you need to provide body for the abstract methods in both interfaces.ExampleIn the following example we have created two interfaces ...
Read MoreGet Enumeration over HashSet in Java
To get enumeration over HashSet, first declare the HashSet and add elements −HashSet hs = new HashSet(); hs.add("P"); hs.add("Q"); hs.add("R");To get enumeration −Enumeration e = Collections.enumeration(hs);The following is an example to get Enumeration over HashSet −Exampleimport java.util.*; public class Demo { public static void main(String[] args) { HashSet hs = new HashSet(); hs.add("P"); hs.add("Q"); hs.add("R"); Enumeration e = Collections.enumeration(hs); while (e.hasMoreElements()) System.out.println(e.nextElement()); } }OutputP Q R
Read MoreA static initialization block in Java
Instance variables are initialized using initialization blocks. However, the static initialization blocks can only initialize the static instance variables. These blocks are only executed once when the class is loaded. There can be multiple static initialization blocks in a class that is called in the order they appear in the program.A program that demonstrates a static initialization block in Java is given as follows:Examplepublic class Demo { static int[] numArray = new int[10]; static { System.out.println("Running static initialization block."); for (int i = 0; i < numArray.length; i++) { ...
Read MoreWrite a program to convert an array to String in Java?
The Arrays class of the java.util package provides a method named toString() this method accepts an array value (of any type) and returns a String.ExampleFollowing Java program accepts various arrays from the user, converts them into String values and prints the results.import java.util.Arrays; import java.util.Scanner; public class ObjectArrayToStringArray { public static void main(String args[]){ Scanner sc = new Scanner(System.in); //Integer array to String System.out.println("Enter 5 integer values: "); int intArray[] = new int[5]; for(int i=0; i
Read MoreInitialize a Set without using add() method in Java
With Java, you can initialize a set without using add() method.For this create a string array −String arr[] = { "A", "B", "C", "D", "E"};Now, use Set and asList() method to initialize the above string array to our Set −Set s = new HashSet(Arrays.asList(arr));The following is an example to initialize a set without using add() method −Exampleimport java.util.Arrays; import java.util.HashSet; import java.util.Set; public class Demo { public static void main(String[] a) { String arr[] = { "A", "B", "C", "D", "E"}; Set s = new ...
Read MoreDemonstrate static variables, methods and blocks in Java
The static variable is a class level variable and it is common to all the class objects i.e. a single copy of the static variable is shared among all the class objects.A static method manipulates the static variables in a class. It belongs to the class instead of the class objects and can be invoked without using a class object.The static initialization blocks can only initialize the static instance variables. These blocks are only executed once when the class is loaded.A program that demonstrates this is given as follows:Examplepublic class Demo { static int x = 10; static ...
Read MoreByteBuffer asLongBuffer() method in Java
A view of the ByteBuffer can be created as a LongBuffer using the asLongBuffer() method in the class java.nio.ByteBuffer. This method requires no parameters and it returns a long buffer as required. This buffer reflects the changes made to the original buffer and vice versa.A program that demonstrates this is given as follows −Exampleimport java.nio.*; import java.util.*; public class Demo { public static void main(String[] args) { int n = 50; try { ByteBuffer bufferB = ByteBuffer.allocate(n); LongBuffer bufferL = bufferB.asLongBuffer(); ...
Read MoreIntStream filter() method in Java
The filter() method of the IntStream class in Java returns a stream consisting of the elements of this stream that match the given predicate.The syntax is as follows −IntStream filter(IntPredicate predicate)Here, the predicate parameter is a stateless predicate to apply to each element to determine if it should be included. The IntPredicate above is the predicate of one int-valued argument.Create an IntStream and add elements −IntStream intStream = IntStream.of(20, 34, 45, 67, 89, 100);Now, set a condition and filter stream elements based on it using the filter() method −intStream.filter(a -> a < 50).The following is an example to implement IntStream ...
Read MoreCan abstract method declaration include throws clause in java?
A method which does not have body is known as abstract method. It contains only method signature with a semi colon and, an abstract keyword before it.public abstract myMethod();Yes, you can throw and exception from an abstract class.ExampleIn the following Java program, we have a two classes: one abstract class with name MyClass which have an abstract method (display()) and, another class that extends the abstract class.Here, the display() method abstract class throws an IOException.Exampleimport java.io.IOException; abstract class MyClass { public abstract void display() throws IOException; } public class AbstractClassExample extends MyClass{ public void display() throws IOException { ...
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