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.
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...
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:
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...
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 :
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.
What is String Interning
String Interning is a method of storing only one copy of each distinct String Value, which must be immutable. In Java String class has a public method intern() that returns a canonical representation for the string object. Java’s String class privately maintains a pool of strings, where String literals are automatically interned.
What is String Interning?
String Interning is a method of storing only one copy of each distinct String Value, which must be immutable. In Java, String class has a public method intern() that returns a canonical representation for the string object. Java’s String class privately maintains a pool of strings, where String literals are automatically interned.
Java String replaceAll() method example
This java tutorial shows how to use the replaceAll() method of java.lang.String class. This method returns a new String object as a result of replacing all the occurrences of the regex pattern with String parameter replacement.
What is the use of String intern method in Java?
Briefly, Java's String class has a public method intern() that returns a canonical representation for the string object. Java's String class privately maintains a pool of strings, where String literals are automatically interned. When the intern() method is invoked on a String object it looks the string contained by this String object in the pool, if the string is found there then the string from the pool is returned. Otherwise, this String object is added to the pool and a reference to this String object is returned.