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Object Oriented Programming Articles
Page 261 of 589
Passing and Returning Objects in Java
As we know it is core concept that in Java there is always pass by value and not by pass by reference.So in this post we will focus on that how this concept get validated in case of passing primitive and passing reference to a method.In case when a primitive type is passed to a method as argument then the value assigned to this primitive is get passed to the method and that value becomes local to that method, which means that any change to that value by the method would not change the value of primitive that you have ...
Read MoreRandom vs Secure Random numbers in Java
Java provides two classes for having random numbers generation - SecureRandom.java and Random.java.The random numbers can be used generally for encryption key or session key or simply password on web server.SecureRandom is under java.security package while Random.java comes under java.util package.The basic and important difference between both is SecureRandom generate more non predictable random numbers as it implements Cryptographically Secure Pseudo-Random Number Generator (CSPRNG) as compare to Random class which uses Linear Congruential Generator (LCG).A important point to mention here is SecureRandom is subclass of Random class and inherits its all method such as nextBoolean(), nextDouble(), nextFloat(), nextGaussian(), nextInt() and ...
Read MoreJava program to convert float decimal to Octal number
We can convert any decimal number to its equivalent octal by following program.In this we reserve the reminder we get after divide the given number by 8 as it is the base of Octal and then reverse the order of reminders we have stored by multiplying each reminder by 10.Let understand by following example.Examplepublic class DecimalToOctal { public static void main(String[] args) { int decimal = 84; int octalNumber = 0, i = 1; while (decimal != 0) { octalNumber += (decimal % 8) * i; decimal /= 8; i *= 10; } System.out.println("Octal of given decimal is " + octalNumber); } }OutputOctal of given decimal is 124
Read MoreJava program to print duplicates from a list of integers
In order to find duplicates we can utilize the property of Set in Java that in Java duplicates are not allowed when going to be added in a Set.Add method of set returns true for the adding value which is not added previously to it while it would return false in case the adding value is already present in the Set.For our agenda we would iterate out list or collection of integer and try to add each integer in a set of type integer.Now if integer gets added than this means that it is occurring for first time and not ...
Read MoreReferencing Subclass objects with Subclass vs Superclass reference
In java inheritance some of the basic rules includes −Object relation of Superclass (parent) to Subclass (child) exists while child to parent object relation never exists.This means that reference of parent class could hold the child object while child reference could not hold the parent object.In case of overriding of non static method the runtime object would evaluate that which method would be executed of subclass or of superclass.While execution of static method depends on the type of reference that object holds.Other basic rule of inheritance is related to static and non static method overriding that static method in java ...
Read MoreCompare two Strings lexicographically in Java programming
We can compare two strings lexicographically using following ways in Java.Using String.compareTo(String) method. It compares in case sensitive manner.Using String.compareToIgnoreCase(String) method. It compares in case insensitive manner.Using String.compareTo(Object) method. It compares in case sensitive manner.These methods returns the ascii difference of first odd characters of compared strings.Examplepublic class Tester { public static void main(String args[]) { String str = "Hello World"; String anotherString = "hello world"; Object objStr = str; System.out.println( str.compareTo(anotherString) ); System.out.println( str.compareToIgnoreCase(anotherString) ); System.out.println( str.compareTo(objStr.toString())); } }Output-32 0 0
Read MoreCount the Number of matching characters in a pair of Java string
In order to find the count of matching characters in two Java strings the approach is to first create character arrays of both the strings which make comparison simple.After this put each unique character into a Hash map.Compare each character of other string with created hash map whether it is present or not in case if present than put that character into other hash map this is to prevent duplicates.In last get the size of this new created target hash map which is equal to the count of number of matching characters in two given strings.Exampleimport java.util.HashMap; public class MatchingCharacters ...
Read MoreDifference between TreeMap, HashMap and LinkedHashMap in Java programming
HashMap, TreeMap and LinkedHashMap all implements java.util.Map interface and following are their characteristics.HashMapHashMap has complexity of O(1) for insertion and lookup.HashMap allows one null key and multiple null values.HashMap does not maintain any order.TreeMapTreeMap has complexity of O(logN) for insertion and lookup.TreeMap does not allow null key but allow multiple null values.TreeMap maintains order. It stores keys in sorted and ascending order.LinkedHashMapLinkedHashMap has complexity of O(1) for insertion and lookup.LinkedHashMap allows one null key and multiple null values.LinkedHashMap maintains order in which key-value pairs are inserted.Exampleimport java.util.HashMap; import java.util.Hashtable; import java.util.LinkedHashMap; import java.util.Map; import java.util.TreeMap; public class Tester { ...
Read MoreDifference between x++ and x= x+1 in Java programming
x++ automatically handles the type casting where as x= x + 1 needs typecasting in case of x is not an int variable. See the example below.Examplepublic class Tester { public static void main(String args[]) { byte b = 2; //Type casting is required //as 1 is int and b is byte variable b = (byte) (b + 1); System.out.println(b); byte b1 = 2; //Implcit type casting by the compiler b1++; System.out.println(b1); } }Output3 3
Read MoreFibonacci of large number in java
Fibonacci numbers of Fibonacci series grows exponentially and can be very large for large numbers like 500 or 1000. To handle such number, long data type is not sufficient. BigInteger can handle large number easily. BigInteger is useful in scenarios where calculations results in data which is out of limit for available primitive data types. See the example below of getting Fibonacci number of 100 and 1000.Exampleimport java.math.BigInteger; public class Tester { public static void main(String args[]) { System.out.println("Fibonacci of 100: "); System.out.println(fibonacci(100)); System.out.println("Fibonacci of 1000: "); ...
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