String In Java

String class available in  java.lang package .

java.lang.String

String in java is defined as , an object that represents sequence of characters.In java , objects of String are immutable which means a constant , and can not be changed once created.

String class provide various important method like : 

toUpperCase() - convert String to upper case.

toLowerCase() - convert String to lower case.

length() - to check length of String.

concat() - to concatenate two String .

split() - to split String.

and many other methods ,each method is used to perform some operation on String value.

Ways To Create String in Java :

check below program where we are creating String type variable using different ways :

public class StringDemo {
	public static void main(String[] args) {
		String websiteUrl="https://www.crtr4u.com";
		String subject=new String("java programming");
		char charArray[] = {'P','Q','R','S','T'};	
		String strFromCharArray= new String(charArray);
		byte[] byteArray= {70,71,72};
		String stringFromByteArray=new String(byteArray);
		
		System.out.println(stringFromByteArray);		
		System.out.println(strFromCharArray);
		System.out.println(subject);	
		System.out.println(websiteUrl);
	}
}

Output :
FGH
PQRST
java programming
https://www.crtr4u.com

Performing different operations on String using inbuilt methods :

package com.suv.string;
public class StringDemo2 {
	public static void main(String[] args) {
		String websiteUrl="https://www.crtr4u.com/2023/01/string-in-java.html";
		String name="Swapnil V";
		String []splittedArray=websiteUrl.split("\\.");
				
		for(String str: splittedArray) {
			System.out.println(str);
		}			
		System.out.println(name.toLowerCase());
		System.out.println(name.toUpperCase());
		System.out.println(name.length());
	}
}

  

Output :

https://www
crtr4u
com/2023/01/string-in-java
html
swapnil v
SWAPNIL V
9

  

The java.lang.String class implements Serializable, Comparable and CharSequence interfaces. Immutable String in Java : immutable means unmodifiable or unchangeable , String object in java is immutable.

check link String vs StringBuffer vs StringBuilder

check link Program to Prove String is immutable and StringBuilder, StringBuffer is Mutable