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Articles by Narasimha Murthi
13 articles
How to find the age when date of birth is known? Using Java?
Java provides a class named Period in the java.time package. This is used to calculate the time period between two given dates as days, months and, years etc.The between() method of this class accepts two LocalDate objects and finds out the period between the two given dates (number of years, months, and days) and returns as a period object.From this, you can extract the number of days, months and, years of the period in between using the getDays(), getMonths() and, getYears() respectively.Finding the ageIf you already have the date of birth of a person, to find the age −Get the ...
Read MoreWhat is 'this' reference in Java?
The this is a keyword in Java which is used as a reference to the object of the current class, with in an instance method or a constructor. Using this you can refer the members of a class such as constructors, variables and methods.Using “this” you can −Differentiate the instance variables from local variables if they have same names, within a constructor or a method.class Student { int age; Student(int age) { this.age = age; } }Call one type of constructor (parametrized constructor or default) from other in a class. It is known as ...
Read MoreCan I overload private methods in Java?
Overloading is a one of the mechanisms to achieve polymorphism where, a class contains two methods with same name and different parameters.Whenever you call this method the method body will be bound with the method call based on the parameters.Overloading private methodsYes, we can overload private methods in Java but, you can access these from the same class.Examplepublic class Calculator { private int addition(int a , int b){ int result = a+b; return result; } private int addition(int a , int b, int c){ int result = a+b+c; ...
Read MoreHow to convert a Date object to LocalDate object in java?
To convert a Date object to LocalDate object in Java −Convert the obtained date object to an Instant object using the toInstant() method.Instant instant = date.toInstant();Create the ZonedDateTime object using the atZone() method of the Instant class.ZonedDateTime zone = instant.atZone(ZoneId.systemDefault());Finally, convert the ZonedDateTime object to the LocalDate object using the toLocalDate() method.LocalDate givenDate = zone.toLocalDate();ExampleFollowing example accepts a name and Date of birth from the user in String formats and converts it to LocalDate object and prints it.import java.text.ParseException; import java.text.SimpleDateFormat; import java.time.Instant; import java.time.LocalDate; import java.time.ZoneId; import java.time.ZonedDateTime; import java.util.Date; import java.util.Scanner; public class DateToLocalDate { public static void main(String ...
Read MoreHow many times finalize method will be invoked? who invokes finalize() method in Java?
The finalize() method belongs to the Object class. Right before closing an object, the garbage collector makes sure that there are no more references to it and, calls the finalize() method on it.Therefore, once you override the finalize() method in it, you can do all the cleanup activity like closing the resources like database connection, network connection, etc.protected void finalize throws Throwable{}It is invoked only once during the execution of a program.Following are some notable points about the finalize method.Since this method belongs the Object class, which is the super class of all the classes in java, you can override ...
Read MoreCan we pass objects as an argument in Java?
Yes, you can pass objects as arguments in Java. Consider the following example: Here we have a class with name EmployeeExampleIn the following Java example, we a have a class with two instance variables name and age and a parameterized constructor initializing these variables.We have a method coypObject() which accepts an object of the current class and initializes the instance variables with the variables of this object and returns it.In the main method we are instantiating the Student class and making a copy by passing it as an argument to the coypObject() method.import java.util.Scanner; public class Student { private ...
Read MoreWhen will be an object eligible for garbage collection?
Java Garbage collector tracks the live object and objects which are no more need are marked for garbage collection. It relieves developers to think of memory allocation/deallocation issues.When an object created in Java program is no longer reachable or used it is eligible for garbage collection.Following are some scenarios where a Java object could be unreachable/unused.Object inside a method − In Java a method is stored in the stack memory. When you call a method, JVM fetches it into the stack and executes it. After the execution it is popped out of the stack then, all its variables will be ...
Read MoreWhat are the main shift operators provided by Java? Explain with an example?
Java provides three shift operators namely −Binary Left Shift Operator. The left operands value is moved left by the number of bits specified by the right operand.Binary Right Shift Operator. The left operands value is moved right by the number of bits specified by the right operand.Shift right zero fill operator. The left operands value is moved right by the number of bits specified by the right operand and shifted values are filled up with zeros.Examplepublic class Test { public static void main(String args[]) { int a = 60;/* 60 = 0011 1100 */ ...
Read MoreWhat is the difference between String, StringBuffer and StringBuilder classes in Java explain briefly?
The String class of the java.lang package represents character strings. All string literals in Java programs, such as "abc", are implemented as instances of this class. Strings are constant, their values cannot be changed after they are created.The StringBuffer and StringBuilder classes are used when there is a necessity to make a lot of modifications to Strings of characters.Unlike Strings, objects of type StringBuffer and String builder can be modified over and over again without leaving behind a lot of new unused objects.The StringBuilder class was introduced as of Java 5 and the main difference between the StringBuffer and StringBuilder ...
Read MoreHow can I swap two strings without using a third variable in Java?
To swap the contents of two strings (say s1 and s2) without the third.First of all concatenate the given two strings using the concatenation operator “+” and store in s1 (first string).s1 = s1+s2;The substring method of the String class is used to this method has two variants and returns a new string that is a substring of this string. The substring begins with the character at the specified index and extends to the end of this string or up to endIndex – 1, if the second argument is given.Now using the substring() method of the String class store the ...
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