An enum cannot have a public constructor; however, private constructors are acceptable (constructors for enums are package-private by default): public enum Coin { PENNY(1), NICKEL(5), DIME(10), QUARTER(25); // usual names for US coins // note that the above parentheses and the constructor arguments match private int value; Coin(int value) { this.value = value; } public … Read more
Java enums (declared using the enum keyword) are shorthand syntax for sizable quantities of constants of a single class. Declaring and using a basic enums Enum can be considered to be syntax sugar for a sealed class that is instantiated only a number of times known at compile-time to define a set of constants. A … Read more
Java EnumMap class is the specialized Map implementation for enum keys. It inherits Enum and AbstractMap classes. the Parameters for java.util.EnumMap class. K: It is the type of keys maintained by this map. V: It is the type of mapped values. Enum Map Book Example import java.util.*; class Book { int id; String name,author,publisher; int … Read more
TreeMap and TreeSet are basic Java collections added in Java 1.2. TreeMap is a mutable, ordered, Map implementation. Similarly, TreeSet is a mutable, ordered Set implementation. TreeMap is implemented as a Red-Black tree, which provides O(log n) access times. TreeSet is implemented using a TreeMap with dummy values. Both collections are not thread-safe. TreeMap of … Read more
The SortedMap in Java. The SortedMap interface extends Map. It ensures that the entries are maintained in ascending key order. Introduction to sorted Map Keypoint: SortedMap interface extends Map. entries are maintained in an ascending key order. Methods of sorted Map : Comparator comparator( ).Object firstKey( ).SortedMap headMap(Object end).Object lastKey( ).SortedMap subMap(Object start, Object end).SortedMap tailMap(Object start). Example: public … Read more
Concepts of weakHashmap in Java Concepts of WeakHashmap Key Points: Implementation of Map. stores only weak references to its keys. Weak References: The objects that are referenced only by weak references are garbage collected eagerly; the GC won’t wait until it needs memory in that case. Difference between Hashmap and WeakHashMap: If the Java memory … Read more
LinkedHashMap in Java class is the Hash table and Linked list implementation of the Map interface, with predictable iteration order. It inherits the HashMap class and implements the Map interface. The important points about Java LinkedHashMap class are: A LinkedHashMap contains values based on the key. It contains only unique elements. It may have one … Read more
Difference between List and Set in Java. The list is a type of ordered collection that maintains the elements in insertion order while Set is a type of unordered collection so elements are not maintained any order. The list allows duplicates while Set doesn’t allow duplicate elements. Related Article: The Set Interface in Java List vs Set import java.util.ArrayList; import java.util.HashSet; import java.util.List; import java.util.Set; public … Read more
The Set interface contains only methods inherited from Collection and adds the restriction that duplicate elements are prohibited. Initialization A Set is a Collection that cannot contain duplicate elements. It models the mathematical set abstraction. Set have its implementation in various classes like HashSet, TreeSet, LinkedHashSet. For example: HashSet: Set set = new HashSet(); Here … Read more
Using Java, developers have the ability to define a class within another class. Such a class is called a Nested Class. Nested Classes are called Inner Classes if they were declared as non-static, if not, they are simply called Static Nested Classes. This page is to document and provide details with examples of how to … Read more
Reference datatypes in java are those which contains reference/address of dynamically created objects. These are not predefined like primitive data types. Dereferencing In Java Dereferencing happens with the . operator: Object obj = new Object();String text = obj.toString(); // ‘obj’ is dereferenced. The Dereferencing follows the memory address stored in a reference, to the place in … Read more
An array is a container object that holds a fixed number of values of a single type. The length of an array is established when the arrays are created. After creation, its length is fixed. Parameter Details ArrayType Type of the array. This can be primitive (int, long, byte) or Objects (String, MyObject, etc). index Index refers to the position of … Read more
A Deque Interface is linear collection that supports element insertion and removal at both ends. The name deque is short for “double ended queue” and is usually pronounced “deck”. Most Deque implementations place no fixed limits on the number of elements they may contain, but this interface supports capacity-restricted deques as well as those with … Read more
The current Deques interface in java. Utility Package is a Queue interface subtype. The Deque is related to the double-ended queue that supports elements from either end of the data structure being added or removed. It can either be used as a queue(first-in-first-out/FIFO) or as a stack(last-in-first-out/LIFO). The usage of the PriorityQueue PriorityQueue is a … Read more
Bit Manipulation in Java – Bitwise and Bit Shift operations. Java enables you to manipulate integers on a bit level, which means operating on specific bits, which represent an integer number. In some cases, it can be really handy. Bit Manipulation Checking, setting, clearing, and toggling individual bits. Using long as bit mask Assuming we want to modify bit n of an integer primitive, i (byte, … Read more
You can compare BigIntegers the same as you compare String or other objects in Java. For example: BigInteger one = BigInteger.valueOf(1); BigInteger two = BigInteger.valueOf(2); if(one.equals(two)){ System.out.println(“Equal”); } else{ System.out.println(“Not Equal”); } Output: Not Equal Note: In general, do not use use the == operator to compare BigIntegers == operator: compares references; i.e. whether two … Read more
Java NumberFormat tutorial shows how to format numbers in Java. Different countries have different number formats and considering this we can have different formats using Locale of java. Using locale can help in formatting Locale locale = new Locale(“en”, “IN”);NumberFormat numberFormat = NumberFormat.getInstance(locale); using above format you can perform various tasks Format Number numberFormat.format(10000000.99); Number … Read more
The BigInteger class is used for mathematical operations involving large integers with magnitudes too large for primitive data types. For example 100-factorial is 158 digits – much larger than a long can represent. BigInteger provides analogues to all of Java’s primitive integer operators, and all relevant methods from java.lang.Math as well as few other operations. … Read more
This example shows how to perform basic mathematical operations using BigDecimal in Java. 1.Addition BigDecimal a = new BigDecimal(“5”);BigDecimal b = new BigDecimal(“7”);//Equivalent to result = a + bBigDecimal result = a.add(b);System.out.println(result); Result : 12 2.Subtraction BigDecimal a = new BigDecimal(“5”);BigDecimal b = new BigDecimal(“7”);//Equivalent to result = a – bBigDecimal result = a.subtract(b);System.out.println(result); Result … Read more
The BigDecimal in java class provides operations for arithmetic (add, subtract, multiply, divide), scale manipulation, rounding, comparison, hashing, and format conversion. The BigDecimal represents immutable, arbitrary-precision signed decimal numbers. This class shall be used in the necessity of high-precision calculation. Comparing BigDecimals The method compareTo should be used to compare BigDecimals: BigDecimal a = new … Read more