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Articles on Trending Technologies
Technical articles with clear explanations and examples
How 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); ...
Read MoreJava Program to calculate the area of a triangle using Heron's Formula
Heron’s formula gives the area of a triangle when the length of all three sides are already known.Let’s say we have the following three sides of a triangle −s1 = 15191235.0; s2 = 15191235.0; s3 = 1.01235479;Now, use the Heron’s formulae to find the area −area = (s1+s2+s3)/2.0d; resArea = Math.sqrt(area* (area - s1) * (area - s2) * (area - s3));Examplepublic class Demo { public static void main(String[] args) { // sides of a triangle double s1, s2, s3; double area, resArea; // three sides of ...
Read MoreRemove all elements from Java LinkedHashSet
To remove all the elements from LinkedHashSet in Java, use the clear() method.The following is an example to declare LinkedHashSet and add elements to it −LinkedHashSet hashSet = new LinkedHashSet(); hashSet.add(10); hashSet.add(20); hashSet.add(30); hashSet.add(40); hashSet.add(50); hashSet.add(60);Use the clear() method to remove all elements −hashSet.clear();The following is an example −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 MoreIterate through a LinkedList using an Iterator in Java
An Iterator can be used to loop through an LinkedList. The method hasNext( ) returns true if there are more elements in LinkedList and false otherwise. The method next( ) returns the next element in the LinkedList and throws the exception NoSuchElementException if there is no next element.A program that demonstrates this is given as follows.Exampleimport java.util.LinkedList; import java.util.Iterator; public class Demo { public static void main(String[] args) { LinkedList l = new LinkedList(); l.add("John"); l.add("Sara"); l.add("Susan"); l.add("Betty"); l.add("Nathan"); ...
Read MoreDeriving a Class in Java
A class can be derived from the base class in Java by using the extends keyword. This keyword is basically used to indicate that a new class is derived from the base class using inheritance. It can also be said that it is used to extend the functionality of the class.A program that demonstrates this is given as follows:Exampleclass A { void funcA() { System.out.println("This is class A"); } } class B extends A { void funcB() { System.out.println("This is class B"); } } public class Demo { public ...
Read MoreWhat is overloading? What happens if we overload a main method in java?
Overloading is one of the mechanisms to achieve polymorphism. If a class contains two methods with the same name and different parameters, whenever you call this method the method body will be bound with the method call based on the parameters.ExampleIn the following Java program, the Calculator class has two methods with name addition. The only difference between them is that one contains 3 parameters and the other contains 2 parameters.Here, we can call the addition method by passing two integers or three integers. Based on the number of integer values we pass, the respective method will be executed.public class ...
Read MoreLongStream mapToInt() method in Java
The mapToInt() method returns an IntStream consisting of the results of applying the given function to the elements of this stream.The syntax is as followsmapToInt(LongToIntFunction mapper)Here, the parameter mapper is the stateless function applied to each element.Declare LongStream and add some elementsLongStream longStream = LongStream.of(1000L, 13000L, 18000L);Now, use the IntStream and mapToInt()IntStream intStream = longStream.mapToInt(val -> (int) val);The following is an example to implement LongStream mapToInt() in JavaExampleimport java.util.*; import java.util.stream.IntStream; import java.util.stream.LongStream; public class Demo { public static void main(String[] args) { LongStream longStream = LongStream.of(1000L, 13000L, 18000L); IntStream intStream = longStream.mapToInt(val ...
Read MoreCreating a Multilevel Inheritance Hierarchy in Java
Inheritance involves an object acquiring the properties and behaviour of another object. So basically, using inheritance can extend the functionality of the class by creating a new class that builds on the previous class by inheriting it.Multilevel inheritance is when a class inherits a class which inherits another class. An example of this is class C inherits class B and class B in turn inherits class A.A program that demonstrates a multilevel inheritance hierarchy in Java is given as follows:Exampleclass A { void funcA() { System.out.println("This is class A"); } } class B extends A ...
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