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Articles on Trending Technologies
Technical articles with clear explanations and examples
What happens if the subclass does not override abstract methods 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();To use an abstract method, you need to inherit it by extending its class and provide implementation to it.A class which contains 0 or more abstract methods is known as abstract class. If it contains at least one abstract method, it must be declared abstract.Extending an abstract classOnce you extend an abstract class in Java you need to override all the abstractmethods in it or, declare it abstract. If you don’t, a ...
Read MoreHow to use the asList() method of the Arrays class to create a Vector object
A Vector can be created from an Array using the java.util.Arrays.asList() method.A program that demonstrates this is given as follows:Exampleimport java.util.Arrays; import java.util.Vector; public class Demo { public static void main(String args[]) { Integer[] arr = { 3, 1, 9, 6, 4, 8, 7 }; Vector vec = new Vector(Arrays.asList(arr)); System.out.println("The Vector elements are: " + vec); } }OutputThe Vector elements are: [3, 1, 9, 6, 4, 8, 7]Now let us understand the above program.The Integer Array arr[] is defined. Then a Vector is created using the Arrays.asList() ...
Read MoreJava Program to get prime numbers using the Sieve of Eratosthenes algorithm
To find all prime numbers up to any given limit, use the Sieve of Eratosthenes algorithm. At first we have set the value to be checked −int val = 30;Now, we have taken a boolean array with a length one more than the val −boolean[] isprime = new boolean[val + 1];Loop through val and set numbers as TRUE. Also, set 0 and 1 as false since both these number are not prime −isprime[0] = false; isprime[1] = false;Following is an example showing rest of the steps to get prime numbers using the Sieve of Eratosthenes algorithm −Examplepublic class Demo { ...
Read MoreCan we declare main() method as private or protected or with no access modifier in java?
Java provides various access specifiers namely private, public and protected etc...The Private modifier restricts the access of members from outside the class. A class and interface cannot be public.The Public access modifier can be associated with class, method, constructor, interface, etc. public can be accessed from any other class.The protected access modifier can be associated with variables, methods, and constructors, which are declared protected in a superclass can be accessed only by the subclasses in other package or any class within the package of the protected members' class.The default access modifier does not have keyword a variable or method declared ...
Read MoreRemove specified element from Java LinkedHashSet
To remove a specified element from LinkedHashSet, use the remove() and include the element you want to remove as a parameter.First, set LinkedHashSet and add elements −LinkedHashSet hashSet = new LinkedHashSet(); hashSet.add(10); hashSet.add(20); hashSet.add(30); hashSet.add(40); hashSet.add(50); hashSet.add(60);Let us now remove an element −hashSet.remove(10);The following is an example to remove specified element from LinkedHashSet −Exampleimport java.util.LinkedHashSet; public class Demo { public static void main(String[] args) { LinkedHashSet hashSet = new LinkedHashSet(); hashSet.add(10); hashSet.add(20); hashSet.add(30); ...
Read MoreLongStream of() method in Java
The LongStream class in Java the following two forms of the of() method.The following of() method returns a sequential LongStream containing a single element. Here is the syntaxstatic LongStream of(long t)Here, parameter t is the single element.The following of() method returns a sequential ordered stream whose elements are the specified values.static LongStream of(long… values)Here, the parameter values are the elements of the new stream.To use the LongStream class in Java, import the following package.import java.util.stream.LongStream;The following is an example to implement LongStream of() method in Java.Exampleimport java.util.stream.LongStream; public class Demo { public static void main(String[] args) { ...
Read MoreThe toString() method of Java AbstractCollection class
The toString() method of the AbstractCollection class is used to return the string representation of the elements of this collection.The syntax is as followspublic String toString()To work with AbstractCollection class in Java, import the following packageimport java.util.AbstractCollection;The following is an example to implement AbstractCollection toString() method in JavaExampleimport java.util.ArrayList; import java.util.AbstractCollection; public class Demo { public static void main(String[] args) { AbstractCollection absCollection = new ArrayList(); absCollection.add("HDD"); absCollection.add("Earphone"); absCollection.add("Headphone"); absCollection.add("Card Reader"); absCollection.add("SSD"); absCollection.add("Pen Drive"); System.out.println("Count ...
Read MoreHow to convert Integer array list to integer array in Java?
To convert integer array list to integer array is not a tedious task. First, create an integer array list and add some elements to it −ArrayList < Integer > arrList = new ArrayList < Integer > (); arrList.add(100); arrList.add(200); arrList.add(300); arrList.add(400); arrList.add(500);Now, assign each value of the integer array list to integer array. We used size() to get the size of the integer array list and placed the same size to the newly created integer array −final int[] arr = new int[arrList.size()]; int index = 0; for (final Integer value: arrList) { arr[index++] = value; }Exampleimport java.util.ArrayList; public class ...
Read MoreCan We declare main() method as Non-Static in java?
The public static void main(String ar[]) method is the entry point of the execution in Java. When we run a .class file JVM searches for the main method and executes the contents of it line by line.You can write the main method in your program without the static modifier, the program gets compiled without compilation errors. But, at the time of execution JVM does not consider this new method (without static) as the entry point of the program. It searches for the main method which is public, static, with return type void, and a String array as an argument.public static int main(String[] ...
Read MoreCreate NavigableMap from TreeMap in Java
To create NavigableMap from TreeMap. The following is the declaration −NavigableMap n = new TreeMap();Now, add some elements to the NavigableMap created above −n.put("A", 888); n.put("B", 999); n.put("C", 444); n.put("D", 555); n.put("E", 666); n.put("F", 888); n.put("G", 999); n.put("H", 444); n.put("I", 555); n.put("J", 666);The following is an example to create NavigableMap from TreeMap and display it −Exampleimport java.util.*; public class Demo { public static void main(String[] args) { NavigableMap n = new TreeMap(); n.put("A", 888); n.put("B", 999); ...
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