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Articles on Trending Technologies
Technical articles with clear explanations and examples
What are annotations in Java?
Annotations are a tag (metadata) which provides info about a program. Annotations in Java Start with the symbol ‘@’. They are used by the compiler to detect errors. Software tools to generate code. They are used to show attributes of an element: e.g. @Deprecated, @Override. Annotation are used to describe the purpose of an element of the framework, e.g. @Entity, @TestCase, @WebService Annotations describe the behaviour of an element: @Statefull, @Transaction. Example class Sample{ public void display(){ System.out.println(" "); } } public class Test extends ...
Read MorePrime number program in Java.
Following is the required program.Examplepublic class Tester { public static void main(String args[]) { int i, m = 0, flag = 0; int n = 41;// it is the number to be checked m = n / 2; if (n == 0 || n == 1) { System.out.println(n + " not a prime number"); } else { for (i = 2; i
Read MoreWrite a java program reverse tOGGLE each word in the string?
To perform a reverse toggle split the words of a string, reverse each word using the split() method, change the first letter of each word to lower case and remaining letters to upper case.Exampleimport java.lang.StringBuffer; public class ToggleReverse { public static void main(String args[]){ String sample = "Hello How are you"; String[] words = sample.split(" "); String result = ""; for(String word:words){ StringBuffer s = new StringBuffer(word); word = s.reverse().toString(); String firstSub = word.substring(0, 1); String secondSub = word.substring(1); result = result+firstSub.toLowerCase()+secondSub.toUpperCase()+" "; } System.out.println(result); } }OutputoLLEH wOH eRA uOY
Read MoreFactorial program in Java without using recursion.
Following is the required program.Examplepublic class Tester { static int factorial(int n) { if (n == 0) return 1; else return (n * factorial(n - 1)); } public static void main(String args[]) { int i, fact = 1; int number = 5; fact = factorial(number); System.out.println(number + "! = " + fact); } }Output5! = 120
Read MoreWhat are unchecked exceptions in Java?
An unchecked exception is the one which occurs at the time of execution. These are also called as Runtime Exceptions. These include programming bugs, such as logic errors or improper use of an API. Runtime exceptions are ignored at the time of compilation. If you have declared an array of size 5 in your program, and trying to call the 6th element of the array then an ArrayIndexOutOfBoundsExceptionexception occurs.Examplepublic class Unchecked_Demo { public static void main(String args[]) { int num[] = {1, 2, 3, 4}; System.out.println(num[5]); } }OutputException in thread "main" java.lang.ArrayIndexOutOfBoundsException: 5 at Exceptions.Unchecked_Demo.main(Unchecked_Demo.java:8)
Read MoreHow to compare two ArrayList for equality in Java?
You can compare two array lists using the equals() method of the ArrayList class, this method accepts a list object as a parameter, compares it with the current object, in case of the match it returns true and if not it returns false.Exampleimport java.util.ArrayList; public class ComparingList { public static void main(String[] args) { ArrayList list1 = new ArrayList(); list1.add("JavaFx"); list1.add("Java"); list1.add("WebGL"); list1.add("OpenCV"); ArrayList list2 = new ArrayList(); list2.add("JavaFx"); list2.add("Java"); list2.add("WebGL"); list2.add("OpenCV"); System.out.println(list2); System.out.println(list1.equals(list2)); } }
Read MoreHow to convert a list collection into a dictionary in Java?
Following is an example to convert a list collection into a dictionary in Java.Exampleimport java.util.ArrayList; import java.util.Dictionary; import java.util.Hashtable; public class CollectionDictionary { public static void main(String[] args) { ArrayList list = new ArrayList(); list.add("JavaFx"); list.add("Java"); list.add("WebGL"); list.add("OpenCV"); System.out.println(list); Dictionary dictionary = new Hashtable(); Hashtable hashTable = new Hashtable(); hashTable.put(1, list.get(0)); hashTable.put(2, list.get(1)); hashTable.put(3, list.get(2)); hashTable.put(4, list.get(3)); System.out.println(hashTable); } }Output[JavaFx, Java, WebGL, OpenCV] {4=OpenCV, 3=WebGL, 2=Java, 1=JavaFx}
Read MoreHow to swap two String variables without third variable.
To swap the contents of two strings (say s1 and s2) without the third, first of all concatenate them and store in s1. Now using the substring() method of the String class store the value of s1 in s2 and vice versa.Examplepublic class Sample { public static void main(String args[]){ String s1 = "tutorials"; String s2 = "point"; System.out.println("Value of s1 before swapping :"+s1); System.out.println("Value of s2 before swapping :"+s2); int i = s1.length(); s1 = s1+s2; s2 = s1.substring(0, ...
Read MoreWhat is static import in Java?
As import statement allows to use a class without its package qualification, static import allows to access the static members of a class without class qualifications. For Example, to access the static methods you need to call the using class name − Math.sqrt(169); But, using static import you can access the static methods directly. Example import static java.lang.Math.*; public class Sample{ public static void main(String args[]){ System.out.println(sqrt(169)); } } Output 13.0
Read MoreWhat are method local inner classes in Java?
In Java, we can write a class within a method and this will be a local type. Like local variables, the scope of the inner class is restricted to the method.A method-local inner class can be instantiated only within the method where the inner class is defined. The following program shows how to use a method-local inner class.Examplepublic class OuterClass { public void display(){ int num = 23; class Inner{ public void print() { System.out.println("This is method inner class "+num); ...
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