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How Constructor Chaining works in Java - Example

How to call one constructor from another constructor in Java or What is Constructor Chaining in Java is one of the tricky questions in Java interviews. Well, you can use this keyword to call one constructor from another constructor of the same class if you want to call a constructor from based class or super class then you can use super keyword. Calling one constructor from other is called Constructor chaining in Java. Constructors can call each other automatically or explicitly using this() and super() keywords. this() denotes a no-argument constructor of the same class and super() denotes a no argument or default constructor of parent class. Also having multiple constructors in the same class is known as constructor overloading in Java.

SQLServerException: The index 58 is out of range - JDBC

I was executing a stored procedure against SQL SERVER 2008 database from Java program using CallableStatement, but unfortunately, I was getting following error "SQLServerException: The index 58 is out of range". Since I am passing a lot of parameters I thought that something is wrong with a number of parameters I was passing to the stored proc. My stored procedure had 58 INPUT parameters, as soon as I removed the 58th INPUT parameter the error goes away, which confirmed my belief that SQL SERVER supports a maximum of 57 INPUT parameters in stored procedure via JDBC. This  seems the really significant limitation, especially for big tables and I was thinking that It's more likely that 58 is not the actual limit and I might have missed something.

What is public private protected and package or default access modifier in Java

public, private, protected and package or default are four access modifiers available in Java. These access modifiers provide Java programmers to control accessibility or visibility of class, method or any field of a class. Good understanding of public, private or protected modifier is required in order to implement proper encapsulation in Java and create a Java program which is easier to maintain. In this Java tutorial, we will see what is public, private, protected and default modifiers are, which modifier can be used with top-level class and nested class and what is the difference between public, private, protected and default modifier in Java.

Difference between StringTokenizer and Split method in Java?

There are multiple ways to split a String in Java, but two of the most common ways are by using StringTokenizer and split method of String class. You can use either one of them, but when to use which one? This short article will give you some details about StringTokenizer and Split method in Java to decide which one to use.

1) The StringTokenizer is legacy, Prefer split() as more chances of its performance getting improved as happens in Java 7.

2) The StringTokenizer doesn't support regular expression, while spilt() does. However, you need to be careful, because every time you call split, it creates a new Pattern object and compiles expression into a pattern. This means if you are using the same pattern with different input, then consider using Pattern.split() method, because compiling a pattern takes more time later to check whether a given string matches a pattern or not.

How to display date in multiple timezone in Java with Example - PST GMT

We can use SimpleDateFormat class to display a date in multiple Timezone in Java. While working in global Java application it's quite common to display dates in the different time zone, classical example is Server is running on either PST or GMT timezone and clients are global or at least running on global trading hubs like Hong-kong, Mumbai, Tokyo, London etc. Unfortunately, Date and Time API in Java is quite tricky and until you have a good understanding of Date and Time classes and methods e.g. Calendar, SimpleDateFormat and thread-safety issue , You can easily create bugs. One of misconception Java programmer has is converting a date in the different timezone. Actually, Date in Java is always in GMT and it represents a number of millisecond since 01-01-1970 00:00 and when we print Date, it calls the toString method and displays date time information in the local timezone.

JDBC - How to Convert java.sql.Date to java.util.Date in Java with Example

How to convert java.sql.Date into a java.util.Date and vice-versa is a popular JDBC interview question which is also asked a follow-up question of the difference between java.sql.Date and java.util.Date which we have seen in our last article. Since both SQL date and Util date store values as a long millisecond, it's easy to convert them back and forth. Both java.sql.Date and java.util.Date provides a convenient method called getTime() which returns long millisecond equivalent of a wrapped date value. Here is a quick example of converting java.util.Date to java.sql.Date and then back to util Date. This article is in the next of earlier posts on Java Date and Time API  like How to convert Date to String and How to find current Date and Timestamp in Java on any timezone. if you haven't read them already you may find them useful.

How to check leap year in Java - program example

Write a Java program to find if a year is a leap year or not is a standard Java programming exercise during various Java programming course on school, colleges and various training institutes both online and offline,  along with other popular homework's e.g. printing Fibonacci numbers, checking palindromes or finding prime numbers. Just to recap a leap year is a year with 366 days which is 1 extra day than a normal year. This extra day comes in the month of February and on leap year Feb month has 29 days than normal 28 days. If you are following then you might know that leap year comes in an interval of 4 years. This year 2012 is a leap year and Feb has 29 days, you can check.

How to remove all white space from String in Java - beginning end and between words

String API in Java provides several utility methods to remove white space from String in Java, from the beginning, end, and between words. White space means blank space including tab characters. One of the classic methods to remove white space from beginning and end of a string in Java is the trim() method, which removes white space from beginning and end. While using trim() method, key thing to remember is that trim() returns a different String object than older one because String is immutable in Java. On the other hand if you want to remove all white spaces from string i.e. white space from beginning, end and between words then you can use replaceAll() method of String and pass regular expression \s to find and replace all white spaces including tab with empty string "".

How to convert String from lowercase to uppercase and lowercase in Java

Convert String from uppercase to lowercase in Java
Sometime we need to convert String from lowercase to uppercase or from uppercase to lowercase e.g. before printing or storing into database etc. String class in Java provides some utility method to perform this case conversion. You can use toUpperCase() to convert any lower case String to uppercase and toLowerCase() to convert any uppercase String to lowercase. Key thing to remember while using toUpperCase() and toLowerCase() is that they return a different String rather than modifying same String because String is immutable in Java. So if you use old String, assuming it has been converted into uppercase or lowercase then you may create but, instead just store new String returned by these methods into same variable which is hold to store old String.

How to Read Input From Console in Java using Scanner Example

Apart from reading file, Scanner can also read user input from Console in Java. Just like in case of reading file, we have provided File as source for scanning, We need to provide System.in as source to scan for user input in Console. Once you created and initialized java.util.Scanner, you can use its various read method to read input from user. If you want to read String, you can use nextLine(), if you want to read integer numbers, you can use nextInt(). Subsequently you can use nextFloat() to read float input, nextDouble() to read double input etc. Scanner class also allows you to define your own pattern and scan for that.

What is difference between Thread vs Process in Java

Thread and Process are two closely related terms in multi-threading and the main difference between Thread and Process in Java is that Threads are part of the process. i.e. one process can spawn multiple Threads. If you run a Java program in UNIX based system e.g. Linux and if that program creates 10 Threads, it still one process and you can find that by using ps -ef | grep identifier command which is one of the most popular use of grep command in UNIX, Where identifier is UNIX the text which can be used as regular expression to find that Java process.

How to convert String to Date Example in Java Multithreading

Data type conversion is one of the most common tasks in programming and a good programmer must know how to convert one type to another type. There are many times when you will be required to convert a String to java.util.Date object mostly in different format e.g. dd-MM-yy or yyyy-MM-dd or simply yyyy MM dd. For example, client pass dates as String to Server or sometimes we read Date related data from CSV file. Java provides API for parsing String to date using DateFormat class, though Java's Date and Time API is severely criticized, it is also the most used Date and Time format solution. Though Joda Date and Time API is always there and now Java 8 also got new date and time API, many of us don't have the luxury to use it in production. Many enterprise application is still running on Java 5 and Java 6, forget about JDK 7 or 8.