How SubString method works in Java - Memory Leak Fixed in JDK 1.7

Substring method from the String class is one of the most used methods in Java, and it's also part of an interesting String interview question e.g. How substring works in Java or sometimes asked as to how does substring creates memory leak in Java. In order to answer these questions, your knowledge of implementation details is required. Recently one of my friends was drilled on the substring method in Java during a Java interview, he was using the substring() method for a long time, and of course, all of us has used this, but what surprises him was the interviewer's obsession on Java substring, and deep-dive till the implementation level.

How to use String in switch case in Java with Example

Have you ever feel that String should be used in switch cases like int and char? JDK 7 has made an important enhancement in their support of String, now you can use String in switch and case statements, No doubt String is the most widely used type in Java, and in my opinion, they should have made this enhancement long back when they provided support for enum in java and allowed enum to be used in a switch statement. 

How to String Split Example in Java - Tutorial

Java String Split Example
I don't know how many times I needed to Split a String in Java. Splitting a delimited String is a very common operation given various data sources e.g CSV file which contains input string in the form of large String separated by the comma. Splitting is necessary and Java API has great support for it. Java provides two convenience methods to split strings first within the java.lang.String class itself: split (regex) and other in java.util.StringTokenizer. Both are capable of splitting the string by any delimiter provided to them. Since String is final in Java every split-ed String is a new String in Java.

How to convert String or char to ASCII values in Java - Example Tutorial

You can convert a character like 'A' to its corresponding ASCII value 65 by just storing it into a numeric data type like byte, int, or long as shown below :

int asciiOfA = (int) 'A';

Here casting is not necessary, simply assigning a character to an integer is enough to store the ASCII value of character into an int variable, but casting improves readability. Since ASCII is a 7-bit character encoding, you don't even need an integer variable to store ASCII values, byte data type in Java, which is 8 bits wide is enough to store the ASCII value of any character.  So you can also do like this :

byte asciiOfB = 'B'; // assign 66 to variable

How to format String in Java – String format Example

String format and printf Example

How to format String in Java is the most common problem developers encounter because of classic System.out.println() doesn’t support formatting of String while printing on console. For those who don’t know What is formatted String? here is a simple definition,  Formatted String is a String that not only displays contents but also displays it in a format that is widely accepted like including comma while displaying large numbers e.g. 100,000,000, etc. Displaying formatted String is one of the needs for modern GUI applications and thankfully Java has good support for formatting String and all other types like Integers, Double, and Date. 

How String in Switch works in Java? Example

Ever Since Java allows using String variables in switch and case statements, there are many programmers using this feature in code, which can be better written using integer and enum patterns. This was one of the popular features of the JDK 7 release, including automatic resource management and multi-exception catch blocks. Though I upfront didn't like this feature because of the better alternatives available in terms of using the enumeration type, I am not totally against this feature. One reason for this is convenience and given usage of String in Java program, it's quite handy as well, but I prefer to learn more before using any new feature in production code.

10 Things Every Java Programmer Should Know about String

String in Java is a very special class and the most frequently used class as well. There are lot many more things to learn about String in Java than any other class, and having a good knowledge of different String functionalities makes you use it properly. Given the heavy use of Java String in almost any kind of project, it becomes even more important to know subtle detail about String. Though I have shared a lot of String related articles already here in Javarevisited, this is an effort to bring some of the String features together. 

How to Split String based on delimiter in Java? Example Tutorial

You can use the split() method of String class from JDK to split a String based on a delimiter e.g. splitting a comma-separated String on a comma, breaking a pipe-delimited String on a pipe, or splitting a pipe-delimited String on a pipe. It's very similar to earlier examples where you have learned how to split String in Java. The only point which is important to remember is little bit of knowledge of regular expression, especially when the delimiter is also a special character in regular expression e.g. pipe (|) or dot (.), as seen in how to split String by dot in Java. In those cases, you need to escape these characters e.g. instead of |, you need to pass \\| to the split method.

String replaceAll() example - How to replace all characters and substring from String

You can replace all occurrence of a single character, or a substring of a given String in Java using the replaceAll() method of java.lang.String class. This method also allows you to specify the target substring using the regular expression, which means you can use this to remove all white space from String. The replaceAll() function is a very useful, versatile, and powerful method and as a Java developer, you must know about it. Even though Java provides separate methods for replacing characters and replacing substring, you can do all that just by using this single method.

Top 10 Low Latency Tips for Experienced Java Developers

Hello guys, If you are preparing for interviews at High-Frequency Trading (HFT) firms, hedge funds, investment banks, or crypto exchanges, then one thing is guaranteed: You will be asked about low latency systems. Building such systems is a completely different ball game. It’s not just about writing clean code — it's about writing fast code that responds in microseconds. I’ve worked on low-latency Java applications that run in production under tight time constraints, and in this post, I’ll share what I’ve learned in easy Indian English, with some practical examples.

Why character array is better than String for Storing password in Java? Example

Why character array is better than String for storing a password in Java was a recent question asked to one of my friends in a java interview. he was interviewing for a Technical lead position and has over 6 years of experience. Both Character array and String can be used to store text data but choosing one over the other is a difficult question if you haven't faced the situation already. But as my friend said any question related to String must have a clue on a special property of Strings like immutability and he used that to convince the interviewer. here we will explore some reasons why should you use char[] for storing passwords than String.

Difference between Stack and Heap memory in Java? Example

The difference between stack and heap memory is a common programming question asked by beginners learning Java or any other programming language. Stack and heap memory are two terms programmers start hearing once they started programming but without any clear and definite explanation. Lack of knowledge of what is a heap in Java and what is stack memory in Java results in misconceptions related to stack and heap. To add to this confusion, a stack is also a data structure that is used to store elements in LIFO(Last In First Out) order and is available in Java API as java.util.Stack.

What is load-on-startup servlet element in web.xml with Example?

load-on-startup is an element that appears inside <servlet> tag in web.xml.4 years back load-on-startup was a very popular servlet interview question because not many Java J2EE developer was familiar with this element and how load-on-startup works inside a servlet container like tomcat or WebSphere. In this J2EE Tutorial, we will see what is a load on startup, how to use the load-on-startup element, and what are different values we can configure for load-On-Startup inside web.xml.

Difference between SendRedirect() and Forward() in JSP Servlet? Example

The difference between SendRedirect and forward is one of the classical interview questions asked during a java web developer interview. This is not just applicable for servlet but also for JSP in which we can use forward action or call sendRedirect() method from scriptlet. Before examining the difference between forward and SendRedirect let’s see what send Redirect method and the forward method does.

SendRedirect ():  

This method is declared in HttpServletResponse Interface.

Signature: void sendRedirect(String url)

Difference between throw and throws in Exception handling - Java Example

Difference between throw and throws keyword on Exception handling in Java is a popular core java interview question. Exception handling being an important part of Java programming language, complete knowledge of all keywords related to exception handling e.g. try, catch, finally, throw and throws is important. Main difference between throw and throws is in there usage and functionality. where throws is used in method signature to declare Exception possibly thrown by any method, throw is actually used to throw Exception in Java code, here is an example of both throw and throws keyword which makes it easy to understand difference between them.