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Java String

Java String

April 30th, 2019

Java String

  • A string is a sequence of characters treated as a unit.
  • A string is a sequence from characters, such essentially the string “Hello” or the string “Hello World”. A string could save some piece of single information or specific text from an entire book.

Java’s powerful built-in String type gives great support for string operations. Each String object v buildings a string of chars, so because “Hello World”, and results over methods that operate in those chars. Us can create a String object within this general method with each new operator.

String greet = new String(“hello world”);
String objects are so common that there is a shorthand literal syntax to create them. we can create a String object simply by writing the desired text within double quotes “like this”. The shorter version of the code below creates a new String object exactly as above.
String greet = “hello”;
It’s valid to create a string made of zero characters – the quotes are right next to each other with nothing in between. This is known as the empty string. The empty string is a valid string object, and the many operations described below work correctly on the empty string where it makes sense.
String empty = “”; // creates an empty string (zero chars)

String Concatenation +

When used between two int values, the + operator does addition. When used between two or more strings, the + operator appends them all together to form a new string.

String start = “Welcome”;

String end = “hungry”;

String result = start + “, I’m ” + end; // result is “Welcome, I’m hungry!”
In computer science, the verb “concatenate” is used for this position – appending sequences commonly to make thing big sequence. This special characteristic of the + operator also runs when each line is combined with a simple before-mentioned as an int or double or char. This story of the +is quite a useful way to mix int and double meanings into a string.
int count = 123;char end = ‘!’;
String result = “I ate ” + count + ” donuts” + end; // “I ate 123 donuts!”

String Immutable Style

String objects apply the “immutable” style, which means that once a string object is built, it never changes. Instead, the + creates different strings value, giving the originals intact. Equally, we examine the various means that orders return to below, the mark that no means changes an actual line. The immutable form is approved since it holds things simple

Java String Functions in Java

Java the programming language now stands first place among all languages. This is not our word but TIOBE index mentioned it. So now you can pursue a lucrative carrier and make a job ready feature by learning java. Gangboard provides full Java course but today we wouldn’t discuss about java, we discuss about another concept called Java String. A sequence of character called string but in java string means an object which refers to characteristic sequences. For creating string object java.lang.String class is necessary.

String objects can be created in two different ways

  1. By string literal: Here you can use double quotes to create Java String literal.
  2. By new keyword: You can use a keyword ”new” to create Java String.

Two different objects are created by Java String one in String pool other in heap. It also creates a reference variable, in which The object in the heap will be referred by variable “s”.
So now get a proper concept about Java String pool.

Java String pool

Heap memory is the storage for collections of String. Java String pool refers to all collection of Strings. If any new object is created String pool will first check its presence in the pool. If it exists then variable will get same reference in return, if not then a new object is created in String pool to return the respective reference.
Here you have to know something that Strings are unable to change like other data types in Java. So The Strings are constant and there values cannot be changed after its creation. For this reason String object can be shared.

String Functions in Java with Example

new String(“text”); explicitly generates each new and referentially separate example from one String object; String s = “text”; may reuse an example of the string constant pool if one is possible.
You very rarely would ever want to use the new String(anotherString) constructor.

String s=”abc”; String s1=”abc”;

String s3 = new String(“abc”);

//OUTPUT – Equal if (s==s1) { System.out.println(“Equal”); }

else { System.out.println(“Not Equal”); }

//OUTPUT – Not Equal if (s==s1) { System.out.println(“Equal”); }

else { System.out.println(“Not Equal”); }

==on two text types is a source identification comparison. Two objects that move equals are not necessarily ==. It is normally wrong to use == on reference types; most of that time just require to be used preferably.
Nonetheless, if during whatever direction you expect to create two equals just not the == string, you can regard the new String(anotherString), constructor. It needs to remain answered again, though, that remains truly wonderful more does rarely specific intention. The equal method is the purpose for checking both string object value is same or not.

String s=”abc”; String s3 = new String(“abc”);

if (s.equals(s3)) { System.out.println(“Equal”); }

else { System.out.println(“Not equal”); }

String s=”abc”; String s3 = new String(“abc”);

if (s.equals(s3)) { System.out.println(“Equal”); }

else { System.out.println(“Not equal”); }

equalsIgnoreCase method it will consider the whether the string object value case sensitive. If value is equal then it’s true otherwise else function going to call.

String s=”abc”; String s3 = new String(“ABC”);
if (s.equalsIgnoreCase(s3))
{ System.out.println(“Equal”); }
else { System.out.println(“Not equal”); }

Java String Methods

Java String length():

Java String Length() method indicates the length of the String. It counts total number of characters in the String and returns to present objects when needed.
length() function returns the length of the string.
String str=”Java”;

Output : 4

Java String compareTo():

Java String compareTo() the given string with existing String. String class implement a method of” Compareable” interface. It will return as number either positive, negative or 0. You will get to know about all String interface after joining our course.

Java String concat() :

Java String concat() method is like combination of string. It is a method where a specific string makes combination with another string and at last return to a combined string. In this method a string get attached with the end of another string.

Java String IsEmpty() :

In this method it checks the string has any contain or empty. When java String is empty it will return either true else false.

Java String Trim() :

For removing the leading and trailing spaces Java String Trim() is used. It used to check the unicode valuation of space character. It checks both before and after the string and if get any existence, removes the spaces and return the omitted string.

Java String toLowerCase():

In the Java String toLowerCase() method all the String characters are converted into lower case. The Java string toLowerCase() system returns the string value in the lowercase character. In another word, it converts all roles of the string into under case letter.

String str = “JavaWorld”;


Output : javaworld

Java String toUpper() :

In the Java String toUpper()  method all the String characters are converted into upper case applying the rules from the default locale.

String str = “JavaWorld”;System.out.println(str.toUpperCase());

Java charAt():

charAt() function returns the character located at the specified index.

String str = “JavaWorld”;System.out.println(str.charAt(2));
Output : v

Java trim():

This method returns a copy of the string, with leading and trailing whitespace omitted.

String str = ”    Java  “;System.out.println(str.trim());
Output : Java

Java split(String regex):

The Java string split() method splits this string against the given regular character and returns value of a String array function.

String str = “JavaWold”;String[] strArray = str.split(“a”);

for(String eachString:strArray){



Output : JV

Java substring():

substring() method returns a part of the string. This method has two variants(overloaded methods).

public String substring(int beginIndex);public String substring(int beginIndex, int endIndex);
The first argument represents the unique origin point of the substring. If that substring() method does call with just one argument, the substring returned value, will include characters from the designated starting point to the end of the original string.
But, if the call to substring() system has two arguments, another dispute defines the endpoint of the substring.

String str = “CoreJavaWorld”;


Output : JavaWorld
[/su_table] And for the other overloaded method:

System.out.println (str.substring (4, 8));

Output : Java

Java String ValueOf():

In the Java String ValueOf() method different types of value are converted into string. Converted values are like int to string, long to string, characte to string r, Boolean to string,float to string, object to string, double to string and char array to string.

Java String replace():

In the Java String replace() method it returns a string to restore new character against all the old character or CharSequence. replace() method replaces occurances of character with a specified new character.

String str = “JavaWorld”;System.out.println(str.replace(‘v’,’V));
Output : JaVa

Java String contains():

In the Java String contains() method makes a search of particular order of characters in the string . If it founds characters are properly ordered then returns true otherwise returns false.

Java String equals():

In this Java String equals() method it compares contents of two given strings  with each other. After all matched it will return true else return false.

Java String equalsIgnoreCase():

In this Java String equalsIgnoreCase() method it also compares two string on content basis but not in equals method. When characters match it also returns true else returns false.

 Java String toCharArray():

In this method string is converted into a character array. This method wiil calculate length and spaces of given Java String then with its content design an array of char type.

Java String GetBytes():

In this method a particular order of byte of string or byte array of string returns.

Java String Is Empty():

In this method it checks the string length is empty or not . If String is 0 then it returns true else false.

Java String endsWith():

In this method it checks whether with given suffix string ends or not . If yes then it returns true else false.
There are three interface implemented by Java String class, Serilizable, Comparable and CharSequence.
There are also two utility classes provided by Java – StringBuffer and Stringbuilder. You will get to know all details after joining our course. So we think that we have provided the basic knowledge over Java . So now you can understand how valuable a Java programmer is. Then why waiting enroll your name in GangBoard provided Java Training Course and fulfill your dream to be an IT professional. Our expert trainer will guide you be a industry ready professional and will assist you to get a handsome job with lucrative salary.So don’t think twice if you want to be a Java Expert  then GangBoard is the right Online Training Institute  where you will get the best Certification  Course for Java .