17,545 total views
17,545 total views In this article, we will discuss how to send an Email using Java Mail. Spring Boot is used to setup dependencies. This code can be used to send mail to any Email server or relay server including Gmail (as a standalone application). POM configurations: spring-boot-starter-mail contains all the basic jars required for this …
2,883 total views
2,883 total views In this post, Gson library is used to serialize data in JSON format to Java object and deserialize it back. Gson is an open source java library created by Google. Nulls are omitted from the JSON output. – toJson() is used to serialize an object to JSON format gson.toJson( object ); – …
Convert from JSON format to Java object and vice versa Read More »
1,688 total views
1,688 total views Data can be read from a file, or written to a file in following ways:– File read using Files.lines method– File read using Files.readAllLines method– File read using Files.readAllBytes method– Write bytes or multiple lines using Files.writeFile method– Lock file for write Example 1: File read using Files.lines method Files.lines method reads all …
2,524 total views
2,524 total views This post covers the following topics on search and filter:– Search for a sub string or char in a string– Search for a string in a list– Filter a string in a list– Filter a sub string in a list– Search for a string in an array Example 1: Search for a sub …
Search / filter for a string or char in a string, list, and array in Java Read More »
1,709 total views
1,709 total views StackOverflowError is a runtime error in Java which most developers would have seen atleast once. This error occurs most often due to deep recursive method call bug in your code. So the solution is to fix the bug. Stack is based on LIFO (Last In First Out) data structure. Each thread has its …
StackOverflowError example in Java, why they occur, and how to fix it Read More »
2,553 total views
2,553 total views In this post, we will see various ways to compress and un-compress String:– Compress and decompress data.– Write string to zip file, and read contents from the same file.– Write string to gz file, and read contents from the same file.All classes mentioned here uses deflate lossless compression algorithm. Difference in compressed data …
Compress string (and create file) and decompress it back in Java Read More »
2,661 total views
2,661 total views There are two ways to implement a thread in java:– By implementing Runnable interface– By extending Thread classIn Java only one class can be extended and hence using Runnable interface is suitable in most cases. Multiple threads can be run at the same time to run tasks in parallel and save time.Note: Be …
Multithreading example in Java using Runnable interface / Thread class Read More »
2,516 total views
2,516 total views In this article we will learn how to create user defined exceptions (checked and unchecked), and why and when to use it. Custom exceptions are useful:– To transform an exception and give the user a proper user readable error.– To group similar exceptions. Say you can group business errors into BUS_ERR_XX error code, …
Custom checked and unchecked exception example in Java Read More »
3,787 total views
3,787 total views In this article the following uses of Enum is mentioned: – Simple enum – Enums with multiple values – Convert enums to String, String[], List – Convert String to enum – Get enum values – Overloaded enum constructors Example 1: Simple enum This enum contains 3 fil type constants, and a default constuctor …
Enum – Common uses in Java including multiple values, and conversions Read More »
1,236 total views
1,236 total views Arrays.sort() can be used to sort arrays in Java in ascending / descending order. Arrays.sort( array ); – This method is used to sort an array in ascending order. Arrays.sort( array, Collections.reverseOrder() ); – To sort an array in descending order. Primitives cannot be sorted in reverse using this method. So if you want to …
Sort an array using Arrays.sort() in Java in ascending or descending order Read More »