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Articles on Trending Technologies
Technical articles with clear explanations and examples
Flow control in a try catch finally in Java
A method catches an exception using a combination of the try and catch keywords. A try/catch block is placed around the code that might generate an exception. Code within a try/catch block is referred to as protected code, and the syntax for using try/catch looks like the following −Syntaxtry { // Protected code } catch (ExceptionName e1) { // Catch block }The code which is prone to exceptions is placed in the try block. When an exception occurs, that exception occurred is handled by catch block associated with it. Every try block should be immediately followed either by ...
Read Morefinal local variable in Java
Local VariableLocal variables are declared in methods, constructors, or blocks.Local variables are created when the method, constructor or block is entered and the variable will be destroyed once it exits the method, constructor, or block.Access modifiers cannot be used for local variables.Local variables are visible only within the declared method, constructor, or block.Local variables are implemented at stack level internally.There is no default value for local variables, so local variables should be declared and an initial value should be assigned before the first use.final Local Variablefinal is the only allowed access modifier for local variables.final local variable is not required ...
Read MoreFinal static variables in Java
Final Static VariablesClass variables also known as static variables are declared with the static keyword in a class, but outside a method, constructor or a block.There would only be one copy of each class variable per class, regardless of how many objects are created from it.Static variables are normally declared as constants using the final keyword. Constants are variables that are declared as public/private, final, and static. Constant variables never change from their initial value.Static variables are stored in the static memory, mostly declared as final and used as either public or private constants.Static variables are created when the program ...
Read MoreFind free disk space using Java
java.io.File class provides following useful methods to figure out the free disk space available.Sr.No.Method & Description1public long getFreeSpace()Returns the number of unallocated bytes in the partition named by this abstract path name.2public long getTotalSpace()Returns the size of the partition named by this abstract pathname.3public long getUsableSpace()Returns the number of bytes available to this virtual machine on the partition named by this abstract pathname.Following example showcases the use of above methods.Example Finalimport java.io.File; import java.text.NumberFormat; public class Tester { public static void main(String[] args) { NumberFormat numberFormat = NumberFormat.getInstance(); numberFormat.setMaximumFractionDigits(2); ...
Read MoreFlexible nature of java.lang.object
The java.lang.Object class is the root of the class hierarchy. Every class has Object as a superclass. All objects, including arrays, implement the methods of this class.Class DeclarationFollowing is the declaration for java.lang.Object class −public class ObjectClass constructorsSr.No.Constructor & Description1Object()This is the Single Constructor.Class methodsSr.No.Method & Description1protected Object clone()This method creates and returns a copy of this object.2boolean equals(Object obj)This method indicates whether some other object is "equal to" this one.3protected void finalize()This method is called by the garbage collector on an object when garbage collection determines that there are no more references to the object.4Class getClass()This method returns the ...
Read MoreFloating point operators and associativity in Java
Following programs shows the float arithmetic can cause dubious result if integer values are used using float variables.Examplepublic class Tester { public static void main(String[] args) { float a = 500000000; float b = -500000000; float c = 1; float sumabc1 = a+(b+c); float sumabc2 =(a+b)+c; System.out.println("Floating Point Arithmetic"); System.out.println("a + ( b + c ) : " + sumabc1); System.out.println("(a + b) + c : " + sumabc2); ...
Read MoreWhy we should use whole string in Java regular expression
In Java regex matches() matches the input string against the whole string as it add a ^ and $ at the end of the input string.so it will not match the substring. So for matching substring, you should use find().Exampleimport java.util.regex.*; class PatternMatchingExample { public static void main(String args[]) { String content = "aabbcc"; String string = "aa"; Pattern p = Pattern.compile(string); Matcher m = p.matcher(content); System.out.println(" 'aa' Match:"+ m.matches()); System.out.println(" 'aa' Match:"+ m.find()); } }Output'aa' Match:false 'aa' Match:true
Read MoreFactory method to create Immutable Map in Java SE 9
With Java 9, new factory methods are added to Map interface to create immutable instances. These factory methods are convenience factory methods to create a collection in less verbose and in concise way.Old way to create collectionsExampleimport java.util.Collections; import java.util.HashMap; import java.util.Map; public class Tester { public static void main(String []args) { Map map = new HashMap(); map.put("A", "Apple"); map.put("B", "Boy"); map.put("C", "Cat"); Map readOnlyMap = Collections.unmodifiableMap(map); System.out.println(readOnlyMap); try { readOnlyMap.remove(0); ...
Read MoreExternalizable Interface in Java
Externalization is used whenever we need to customize serialization mechanism. If a class implements an Externalizable interface then, object serialization will be done using writeExternal() method. Whereas at receiver's end when an Externalizable object is a reconstructed instance will be created using no argument constructor and then the readExternal() method is called.If a class implements only Serializable interface object serialization will be done using ObjectoutputStream. At the receiver's end, the serializable object is reconstructed using ObjectInputStream.Below example showcases usage of Externalizable interface.Exampleimport java.io.Externalizable; import java.io.FileInputStream; import java.io.FileOutputStream; import java.io.IOException; import java.io.ObjectInput; import java.io.ObjectInputStream; import java.io.ObjectOutput; import java.io.ObjectOutputStream; public class ...
Read MoreDouble brace initialization in Java
Double braces can be used to create and initialize objects in a single Java expression. See the example below −Exampleimport java.util.ArrayList; import java.util.List; public class Tester{ public static void main(String args[]) { List list = new ArrayList(); list.add("A"); list.add("B"); list.add("C"); list.add("D"); list.add("E"); list.add("F"); System.out.println(list); List list1 = new ArrayList() { { add("A"); add("B");add("C"); add("D");add("E");add("F"); ...
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