string manipulation java

                                    String manipulations:
charAt(indexNumber): it returns the char at the given index
length(): returns the total number of characters as int
		length is ALWAYS one unit above the maximum index number
		maxIndex: length()-1;
concat(Value): Concatenation, concats the given value to the 
String and returns a new value
toLowerCase(): converts to lowercase and returns a new String
toUpperCase(): converts to uppercase and returns a new String
trim(): removes the unused spaces , and returns new String
substring(beginning index, ending index): 
creates substring of the string value from the beginning index 
till the ending                   
substring(beginning index): 
creates substring of the string value from the beginning index 
till the end of the stringreplace(old Value, new Value): new value 
will be replaced with ALL the given old value, and returns new string 
replaceFirs(old Value, new Value): 
new value will be replaced with  the very first given old value, 
  and returns new string
indexOf(Value): 
returns the index number of the first occurred character as an int             
indexOf(Value): returns the index number of first 
occurred character,as int
lastIndexOf(Value): return the index number of 
last occurred character, as int
isEmpty(): identifies if the string is empty
                true ==> string is empty,
                false ==> String is not empty
equals(str): checks if two string' visible texts are equal or not
                    cares about the case sensitivity
                        A == a  ==> false
 equalsIgnoreCase(str):  checks if two string' visible texts 
are equal or not
                 does not care case sensitivity
                    A == a ==> true
 contains(str): checks if the str is contained in the string. 
 returns boolean
                    if str is conatined ==> true
                    otherwise ==> false
 startsWith(str): checks if the string starts with the given str. 
 returns boolean
                if starts with str ==> true
                otherwise ==> false
endsWith(str): checks if the string ended with the given str. 
returns boolean
                 if ended with str ==> true
                    otherwise ==> false

                                         System.out.println("abc");
     String cde = "cde";
     System.out.println("abc" + cde);
     String c = "abc".substring(2,3);
     String d = cde.substring(1, 2);
 

                                         String str = "abc";