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Java Articles
Page 82 of 450
How to prevent Cloning to break a Singleton Class Pattern in Java?
A Singleton pattern states that a class can have a single instance and multiple instances are not permitted to be created. For this purpose, we make the constructor of the class a private and return a instance via a static method. But using cloning, we can still create multiple instance of a class. See the example below − Example - Breaking Singleton public class Tester{ public static void main(String[] args) throws CloneNotSupportedException { A a = A.getInstance(); ...
Read MorePrivate Constructors and Singleton Classes in Java Programming
As we know the primary role of the constructor is to instantiate a class object now if we made the constructor as private then we restrict its calling to be only in defining a class and not in some other class. Now the singleton class in Java is defined as the class which restricts the instantiation of a class and ensure that only one instance of the class exists in the JVM. After first time if instantiate the singleton class the new variable also points to the first instance created. In order to create a singleton class we could use ...
Read MorePrivate and final methods in Java Programming
In Java private methods are the methods having private access modifier and are restricted to be access in the defining class only and are not visible in their child class due to which are not eligible for overridden. However, we can define a method with the same name in the child class and could access in parent class.Like private methods final methods in Java are the methods having final non-access modifier instead of private and are again restricted to be accessed in the defining class only and are not visible in their child class due to which are not eligible ...
Read MoreSorting collection of String and StringBuffer in Java
In order to sort in Java as we know we can use either Comparable or Comparator interfaces in which we could also define our custom logic to sort.One of the approach to sort is to add the entity in TreeSet or TreeMap which would sort the entries as internally they also uses the comparable interface. Now String class in Java internally implements comparable interface so whenever we add string to a tree set or map it uses comparable logic of string class and sort the input entry strings.But String buffer do not have the implementation of comparable interface so ...
Read MoreSwap two variables in one line in Java
In order to swap two variable using single expression or in single line we could use bitwise XOR operator of Java. As we now that in Java XOR functions as XOR of two numbers a and b returns a number which has all the bits as 1 wherever bits of a and b differs. So for swapping of two variable we would use this operator as Example public class SwapUsingBitwise { public static void main(String[] args) { int a = 8 ; int b = 10; ...
Read MoreSwapping Characters of a String in Java
For swapping characters of a string in Java we can use string builder which is mutable so we need not to take care of new object creation during swapping. In this we would create a method which swap characters of string based on location of swapping characters.This method will take location of swapping characters as its parameters.First store both characters need to be swapped and using set character method of string builder swap the targeted characters. Example public class SwapCharacters { public static void main(String[] args) { String str = ...
Read MoreJava Program to concatenate a String and Integers
To concatenate a String and some integer values, you need to use the + operator. Let’s say the following is the string. String str = "Demo Text"; Now, we will concatenate integer values. String res = str + 1 + 2 + 3 + 4 + 5; The following is the final example. Example public class Demo { public static void main(String[] args) { String str = "Demo Text"; System.out.println("String = "+str); String res = str + 1 + 2 + 3 + 4 + 5; System.out.println(res); } } Output String = Demo Text Demo Text12345
Read MoreJava program to check if binary representation is palindrome
A palindrome is a sequence that is same both forwards and backwards. The binary representation of a number is checked for being a palindrome but no leading 0’s are considered. An example of this is given as follows − Number = 5 Binary representation = 101 The binary representation of 5 is a palindrome as it is the same both forwards and backwards. A program that demonstrates this is given as follows. Example public class Example { public static void main(String argc[]) { long num = 5, n1; ...
Read MoreDifferent ways to format long with Java System.out.format
The System.out.format is used in Java to format output. Here, let’s say the following is our long. long val = 787890; To format, we have considered the following that justifies the output. System.out.format("%d%n", val); System.out.format("%9d%n", val); System.out.format("%+9d%n", val); System.out.format("%08d%n", val); System.out.format("%, 9d%n", val); The following is the complete example that displays the difference in output as well. Example import java.util.Locale; public class Demo { public static void main(String []args) { long val = 787890; System.out.format("%d%n", val); ...
Read MoreHexadecimal integer literal in Java
For Hexadecimal, the 0x or 0X is to be placed in the beginning of a number. Note − Digits 10 to 15 are represented by a to f (A to F) in Hexadecimal Here are some of the examples of hexadecimal integer literal declared and initialized as int. int one = 0X123; int two = 0xABC; Example public class Demo { public static void main(String []args) { int one = 0X123; int two = 0xABC; System.out.println("Hexadecimal: "+one); System.out.println("Hexadecimal: "+two); } } Output Hexadecimal: 291 Hexadecimal: 2748
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