String In java

What is String Class in Java ?

• String class represent character string. All string in  java implemented as instance of class.
• String class is an Immutable java class It can not be modified and it uses string table.
• String class in java is one which is used most.

There are various methods in string class which are used to manipulate string. String Class possess eleven constructor which allow you to manipulate string.

Simple way to create string in java.

String s="Welcome to my Blog"; //String s contains Welcome to my Blog 

Few methods of String Class are as follows:-

• Char CharAt(int index) :- Returns a character at specified index.
• int indexOf(char ch):- Returns index of first occurrence of  specified character.
• int compareTo(object o):- compare string with another object.
• int length():- Returns length of string.
• String toLowerCase(): Converts all the character of string to lower case.

String example: Some methods of string class:

If you have More time there is a video  you can look and learn from it 

For  video in Hind  language click here

Program:
package xyz;
public class stringexp {

public static void main(String[] args) {
String s1="Welcome to Java";
  String s2 = s1;
String s3 = new String("Welcome to Java");
String s4 = "Welcome to Java";
System.out.println("this are four strings"+"\n"+s1+"\n"+s2+"\n"+s3+"\n"+s4);
System.out.println("s1==s2:"+s1==s2);
 System.out.println("s2==s3:"+s2==s3);
System.out.println("s1.equals(s2):"+s1.equals(s2));
System.out.println("s2.equals(s3):"+s2.equals(s3));
System.out.println(" s1.compareTo(s2): " +s1.compareTo(s2));
System.out.println("s2.compareTo(s3):" +s2.compareTo(s3));
System.out.println("s1 == s4:"+s1 == s4 );
System.out.println("character at 0:"+s1.charAt(0));
System.out.println("index of string j:"+s1.indexOf('J'));
System.out.println("index of string to:"+s1.indexOf("to"));
System.out.println("last index of a:"+s1.lastIndexOf('a'));
System.out.println("last index of o:"+s1.lastIndexOf("o", 15));
System.out.println("lenth of string:"+s1.length());
System.out.println("from 5th character of string: "+s1.substring(5));
System.out.println("from 5th to 11th character:"+s1.substring(5, 11));
System.out.println("check if it start with wel :"+s1.startsWith("Wel"));
System.out.println("check if it ends with (java):"+s1.endsWith("Java"));
System.out.println("string to lowercase:"+s1.toLowerCase());
System.out.println("string to uppercase:"+s1.toUpperCase());
System.out.println("Welcome "+s1.trim());
System.out.println("replace o with T: "+s1.replace('o', 'T'));
System.out.println("replace all the 'o' by character 'T':"+s1.replaceAll("o", "T"));
System.out.println("replace only 1st 'o' with 'T':"+s1.replaceFirst("o", "T"));
char[] array = s1.toCharArray();
System.out.println(" convert sting to character : ");
for(int i=0;i {
     System.out.print(array[i]+" ");
}
  }

}

Output:

this are four strings

Welcome to Java

Welcome to Java

Welcome to Java

Welcome to Java

false

false

s1.equals(s2):true

s2.equals(s3):true

 s1.compareTo(s2): 0

s2.compareTo(s3):0

false

character at 0:W

index of string j:11

index of string to:8

last index of a:14

last index of o:9

lenth of string:15

from 5th character of string: me to Java

from 5th to 11th character:me to 

check if it start with wel :true

check if it ends with (java):true

string to lowercase:welcome to java

string to uppercase:WELCOME TO JAVA

Welcome Welcome to Java

replace o with T: WelcTme tT Java

replace all the 'o' by character 'T':WelcTme tT Java

replace only 1st 'o' with 'T':WelcTme to Java

 convert sting to character : 

W e l c o m e   t o   J a v a