Java String replace Code
Java String Replace Tutorial
This String replace example in Java will show you how to replace String in Java both at character level and by using regular expression. Since String is final in Java every time you replace String you will get a new String object only if your actually replace anything on original String otherwise replace methods of String return same String object. String Class in Java provides 4 methods to replace String in Java. Those methods allow you to replace character from String, replace CharacterSequence from String, replace all occurrence of pattern in String or just first occurrence of any pattern in Java. We will also see important points on String replace method and how to make best use of regular expression while replace string in Java.
How to replace String: character substring replaceAll example
In this Java tutorial, we will see How to replace characters and substring from String in Java. First example in this program replaces a character, i.e. it replaces "J" with "K", which creates "Kava" from "Java". Second String replace example, replaces words from String, it replaces Scala with Java. Third and fourth example shows how to use regular expression to replace String in Java. Both examples uses \\s to match spaces or any white space character and replace with #. Third one uses replaceFirst() which only replace first match, while fourth one uses replaceAll() which replaces all matches.
Hidden evils of Java’s String.split() and replace()
If you code in Java, you have inevitably used the String.split() and String.replace() (including replaceFirst() and replaceAll()) functions. And why wouldn’t you? They are much more convenient than using the Java Regular Expressions API where you need to create a ‘Pattern‘ object, and possibly a ‘Matcher‘, and then call methods on those.
Java String provides a lot of concepts that can be performed on a string such as compare, concat, equals, split, length, replace, compareTo, intern, substring etc. In java, string is basically an object that represents sequence of char values.
String split example
I don't know how many times I need to Split String in Java. Split is very common operation given various data sources e.g CSV file which contains input string in form of large String separated by 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 to split 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 remove XML special characters from Java String with Example
There are two approaches to replace XML or HTML special characters from Java String, First, Write your own function to replace XML special characters or use any open source library which has already implemented it. Luckily there is one very common open source library which provides function to replace special characters from XML String is Apache commons lang’s StringEscapeUtils class which provide escaping for several languages like XML, SQL and HTML. you can use StringEscapeUtils to convert XML special character in String to there escaped equivalent. I personally like to use open source code instead of reinventing the wheel to avoid any testing efforts.
Java String intern Example
In Java, when we talk about String interning, we describe how Java stores only one copy of every distinct String value in the string pool, in order to reuse String objects to save memory from a program. This practically means, that each String object is stored only once in memory, regardless of how many times the same String may appear in the code. So, as you already guessed, in this example we are going to talk about interning Strings and comparing them with the use of intern() method.
Top 10 Questions for Java Regular Expression
How to extract numbers from a string? How to split Java String by newlines? Importance of Pattern.compile()? How to escape text for regular expression? Why does String.split() need pipe delimiter to be escaped? How to replace 2 or more spaces with single space in string and delete leading spaces only? and many more...
Java String Class
Java String Class is immutable, i.e. Strings in java, once created and initialized, cannot be changed on the same reference. A java.lang.String class is final which implies no class and extend it. The java.lang.String class differs from other classes, one difference being that the String objects can be used with the += and + operators for concatenation.
String vs StringBuffer vs StringBuilder
Difference between String, Stringbuffer and StringBuilder: In this Java tutorial we will see What is String in Java, some important properties of String in Java, What is StringBuffer in Java , When to use StringBuffer in Java , StringBuilder in Java and how it can be used in place of StringBuffer, What are differences between String and StringBuffer and StringBuilder in Java which is a frequently asked core Java question and mostly String vs StringBuilder vs StringBuffer.
Java String is Special
A Java String contains an immutable sequence of Unicode characters. Unlike C/C++, where string is simply an array of char, A Java String is an object of the class java.lang. Java String is, however, special. Unlike an ordinary class:
3 Examples to Concatenate String in Java
String concatenation is the process of joining two or more small String to create a big String. For example you can create full name by concatenating first and last name of a person. Java provides multiple ways to concatenate String, but the easiest of them is by using + operator. It is one of the magical operator in Java, though Java doesn't support operator overloading, it has made an exception in case of String and + operator. Plus operator is a binary operator and primarily used to add two numbers if both operands are integer but it can also used to concatenate String if either both or first operand is String.
5 ways to check if String is empty
String in Java is considered empty if its not null and it’s length is zero. By the way before checking length you should verify that String is not null because calling length() method on null String will result in java.lang.NullPointerException. Empty String is represented by String literal “”. Definition of empty String may be extended to those String as well which only contains white space but its an specific requirement and in general String with white space are not considered as empty String in Java. Since String is one of the most frequently used class and commonly used in method arguments, we often needs to check if String is empty or not. Thankfully there are multiple ways to find if String is empty in Java or not. You can also count number of characters in String, as String is represented as character array and decide if String is empty or not. If count of characters is zero than its an empty String. In this Java String tutorial we going to see 5 ways to find if any String in Java is empty or not. Here are our five ways to check empty String :
Parsing String to Enum and Converting Enum to String
Converting Enum into String and parsing String to Enum in Java is becoming a common task with growing use of Enum. Enum is very versatile in Java and preferred choice to represent bounded data and since is almost used everywhere to carry literal value its important to know how to convert Enum to String in Java. In this article we will see both first converting Strings to Enum in Java and than Changing an Enum to String in Java with Example.
Difference between String literal and New String object in Java
String is a special class in Java API and has so many special behaviours which is not obvious to many programmers. In order to master Java, first step is to master String class, and one way to explore is checking what kind of String related questions are asked on Java interviews. Apart from usual questions like why String is final, or equals vs == operator, one of the most frequently asked question is what is difference between String literal and String object in Java. For example, what is the difference between String object created in following two expression...
Right way to check if String is empty
What do you most of us do while using String in Java? checking whether String is null or empty right? I am sure you know couple of way to test whether String is empty or not, but do you know the right way to do it? When we talk about Strings in Java, we can imagine them as arrays of characters, and they are, but in Java they are also object. An empty Java String, is considered as the not null String that contains zero characters, meaning its length is 0.
Summary of the String Class
A Java String contains an immutable sequence of Unicode characters. Unlike C/C++, where string is simply an array of char, A Java String is an object of the class java.lang.
Why String is immutable or final
This is one of the most popular String Interview questions in Java, which starts with discussion of, What is String, How String in Java is different than String in C and C++, and then shifted towards what is immutable object in Java , what are the benefits of immutable object , why do you use it and which scenarios do you use it. This is some time also asked as "Why String is final in Java".
How to convert String to Date
SimpleDateFormat in Java can be used to convert String to Date in Java. java.text.SimpleDateFormat is an implementation of DateFormat which defines a date pattern and can convert a particular String which follows that pattern into Date in Java.This is the second part of the article on java.util.Date and String in Java. In the first part we have seen How to convert Date to String in Java. SimpleDateFormat accepts a String in any date format e.g. yyyyMMdd is a date pattern and 20110924 is a String in that format. Now you want to create a java.util.Date object from this String.
string pooling : String.intern method
This article will describe how String.intern method was implemented in Java 6 and what changes were made in it in Java 7 and Java 8. String pooling (aka string canonicalisation) is a process of replacing several String objects with equal value but different identity with a single shared String object. You can achieve this goal by keeping your own Map (with possibly soft or weak references depending on your requirements) and using map values as canonicalised values. Or you can use String.intern() method which is provided to you by JDK.