Obtaining the Java Development Kit

Now that the theoretical underpinning of Java has been explained, it is time to start writing Java programs.

Click here To Know More On JAVA

Before you can compile and run those programs, however, you must have a Java development system installed on your computer. The one used by this book is the standard JDK (Java Development Kit), which is available from Sun Microsystems. Several other Java development packages are available from other companies, but we will be using the JDK because it is available to all readers. It also constitutes the final authority on what is and isn’t proper Java. At the time of this writing, the current release of the JDK is the Java 2 Platform Standard Edition version 5 (J2SE 5). Because J2SE 5 contains many new features that are not supported by earlier versions of Java, it is necessary to use J2SE 5 (or later) to compile and run the programs in this book.

The JDK can be downloaded free of charge from www.java.sun.com. Just go to the download page and follow the instructions for the type of computer that you have. After you have installed the JDK, you will be ready to compile and run programs.

The JDK supplies two primary programs.

1. The first is javac.exe, which is the Java compiler.
2. The second is java.exe,which is the standard Java interpreter, and is also referred to as the application launcher.

One other point: the JDK runs in the command prompt environment. It is not a windowed application. In order to Understand how to install JDK for eclipse check below link

How to Install JDK For Eclipse

How to Convert String to Date in Java

This is the second part of the article which I have started around date and String in Java. In the first part we have seen about converting a java.util.

Check Here For How To Convert date To String In JAVA

Date object into String format and in this part we will see the other way around. Means you have String in any date format e.g. yyyyMMdd 20110924 and you want to create a java.util.Date object from that. We will list steps to convert String into Date in Java and then we will see different examples with different date formats e.g. ddMMyy or dd-MM-yyyy.

You can check the java doc of DateFormat for all the symbols it supports and what is meaning for that but here I am listing some common points which is worth remembering while working with SimpleDateFormat for conversion.

1) Confusion between “m” and “M”, small case “m” represent minutes while “M” represent Month Also “d” represent date in month while “D” represent Day of week. This is most common cause of error while converting String to date and back date to string. In shot ddMMyy is not equal to DDmmyy.

2) SimpleDateFormat is not thread-safe. They are not synchronized so its better you create separate SimpleDateFormat for each thread to avoid any race condition while parsing.

How to Convert Date to String in Java

Some times we need to convert java.util.Date to string in java may for displaying purpose I need it that while working on displaytag then I thought about this article to list down various way of converting this in various ways, after some reading I found that SimpleDateFormat makes this quite easy. To get the feel of Date API in java and to familiarize ourselves with these classes we will see different examples of converting date to String in our application. Both DateFormat and SimpleDateFormat class belongs java.text package and they are very powerful and you can use them for conversion. It is also good for parsing string into date and can be used to show in various locale also.

Its very easy with the use of SimpleDateFormat, here are the exact steps:

convert date to string, simpleDateFormat in Java

1) First step is to create a date format using SimpleDateFormat class

2) Call format() method of SimpleDateFormat by passing Date object this will return String representation of date into specified date format.

For complete details on available symbols for date conversion you can check java doc of DateFormat and SimpleDateFormat class. Here are some important points about SimpleDateFormat which is worth remembering

1)Common point of confusion between “m” and “M” , small case “m” represent minutes while “M” represent Month Also “d” represent date in month while “D” represent Day of week. This is most common cause of error while converting String to date and back date to string. In shot ddMMyy is not equal to DDmmyy.

2)It’s also worth noting that SimpleDateFormat are not thread-safe. They are not synchronized so its better you create separate DateFormat for each thread to avoid any race condition while parsing date in java.

It’s very important for any java developer be it senior or junior to get familiarize himself with Date, Time and Calendar API. SimpleDateFormat is an excellent utility for converting String to Date and then Date to String but you just need to be little careful with format and thread-safety .

How to reverse String in Java using Iteration and Recursion

Here is code example String reverse using iterative and recursive function written in Java. Recursive solution is just for demonstrative and education purpose, don’t use recursive solution in production code as it may result in StackOverFlowError if String to be reversed is very long String or if you have any bug in your reverse function, anyway its good test to make yourself comfortable with recursive functions in java.