Base64 Encoding Decoding Example in Java 8

Until Java 8, there was no standard way to Base64 encode a String in Java or decode a base64 encoded String. Java Programmers either use Apache Commons library and it's Base64 class to encode or decode binary data into base 64 encoding, as shown here, or rely on internal Sun classes e.g. sun.misc.BASE64Encoder and sun.misc.BASE64Decoder(), which were not officially part of JDK and can be removed without notification. Java 8 solves this problem by providing standard support for base64 encoding and decoding by providing a java.util.Base64 class. This class contains methods like getEncoder() and getDecoder() to provide Base64 encoder and decoder to carry out base 64 encoding of String or binary data. In this article, I'll show you some example of how to base64 encode String in Java 8.

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Best books to Learn Java 8

I often receive emails and queries asking about some good books to learn Java 8. Since Java 8 is very different from any other JDK release, in terms of language and API enhancement you really need a good book to learn fundamentals. In short, based upon my 2 years of learning and reading Java 8 books, I can say that Java SE 8 for Really Impatient is hands down the best book to learn Java 8. It covers all the essential things released in JDK 8, not just lambda expression and streams but also new Date and Time API and several other minor enhancement yet important features, which often goes un-noticed. It doesn't scare you with comprehensive detail as well and tell you what you need to know as an application developer. It's not going to teach you fundamentals of functional programming, but it will teach you how to use the map and flatMap operations.

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How to convert java.util.Date to java.time.LocalDate in Java 8 - Example

The easiest way to convert a java.util.Date to java.time.LocalDate is via Instant, which is the equivalent class of java.util.Date in JDK 8. You can first convert util Date to Instant and then create a LocalDateTime object from that instant at your default timezone. Once you have an instant of LocalDateTime, you can easily convert that to LocalDate or LocalTime in Java. If you are not living under the rock in last two years that its 2016 and Java 8 has been around for more than 2 years, 18th March 2014 Java SE 8 GA happened. In the third attempt of designing a robust date and time API, JDK 8 has come up with JSR 318 new Date and Time API and many programmers have already started using it.

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3 ways to get number of months and year between two dates in Java?

Earlier I have talked about how to calculate a number of days between two dates in Java (see here), and now you will learn how to get the number of months and years between dates. Though it may look easy, it's not that easy to calculate months and years between dates, unless you take care of all kinds of nuisances like Daylight saving time and when daylight change occurs, leap seconds, and an extra day added in a leap year. Unfortunately, JDK doesn't have a standard method like Period.between() method of Java 8 before to solve this problem. So, if you have to calculate the number of months and years between given dates, you have three main options, first, use Calendar class to write your method to find a number of months and year between given dates, second, use Joda-time library and the third option is to upgrade to Java 8.

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10 Examples of Joining String in Java 8 - StringJoiner and String.join()

It's quite common in day to day programming to join Strings e.g. if you have an array or List of String let's say {Sony, Apple, Google} and you want to join them by comma to produce another String "Sony, Apple, Google", there is not an easy way to do it in Java. You need to iterate through array or list and then use a StringBuilder to append a comma after each element and finally to remove the last comma because you don't want a comma after the last element. A JavaScript-like Array.join() method or join() method of Android's TextUtils class is what you need in this situation, but you won't find any of such method on String, StringBuffer, StringBuilder, Arrays, or Collections class until Java 8. Now, you have a class called StringJoiner which allows you to join multiple String by a delimiter.

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10 Examples of Converting a List to Map in Java 8

Suppose you have a List of objects, List and you want to convert that to a Map, where a key is obtained from the object and value is the object itself, how do you do it by using Java 8 stream and lambda expression? Prior to Java 8, you can do this by iterating through the List and populating the map by keys the and values. Since it's iterative approach and if you are looking for a functional solution then you need to use the stream and lambda expression, along with some utility classes like Collectors, which provides several useful methods to convert Stream to List, Set or Map. In the past, we have seen how to use the Collectors.groupingBy() method to group elements in Set and In this article, we will use Collectors.toMap() method to convert a List of an object into a Map in Java.

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How to find the first element of Stream in Java 8 - findFirst() Example

In Java 8, you can use the Stream.findFirst() method to get the first element of Stream in Java. This is a terminal operation and often used after applying several intermediate operations e.g. filter, mapping, flattening etc. For example, if you have a List of String and you want to find the first String whose length is greater than 10, you can use the findFirst() method along with stream() and filter() to get that String. The stream() method gets the Stream from a List, which then allow you to apply several useful methods defined in the java.util.Stream class e.g. filter(), map(), flatMap() etc.

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Difference between map() and flatMap() in Java 8 Stream

The map() and flatmap() are two important operations in new functional Java 8. Both represents functional operation and they are also methods in java.util.stream.Stream class. The key difference between map() and flatmap() function is that when you use map(), it applies a function on each element of stream and stores the value returned by the function into a new Stream. This way one stream is transformed into another e.g. a Stream of String is transformed into a Stream of Integer where each element is length of corresponding Stream. Key thing to remember is that the function used for transformation in map() returns a single value. If map() uses a function, which, instead of returning a single value returns a Stream of values than you have a Stream of Stream of values, and flatmap() is used to flat that into a Stream of values.

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