Strings and StringBuffers

A string is a sequence of character. A string will have fixed number of character. In java a string is object of the class which belongs to the java lang.string.

    String constructors:
The string class supports several constructors to create an empty string we can call the default constructors.

1. String object=new String();
2. String object=new String(char, char[])
3. String object = new String(char array, int start, int numchars)
4. String object=new String(string object)
5. String object=new String(byte ASCII char array)
6. String object=new String(byte ASCII char array, int start, int num chars)

class Sample
{
public static void main(String args[])
{
String S=new String();
S="Hello";
System.out.println(S);

                char A[]={'v','i','s','i','o','n'};
String K=new String(A);
System.out.println(K);

                String P=new String(A,2,3);
System.out.println(P);

                String S1="Welcome";
String S2=new String(S1);
System.out.println(S1+S2);

                byte ascii[]={65,66,67,68,69};
String S3=new String(ascii);
System.out.println(S3);

String S4=new String(ascii,2,3);
System.out.println(S4);
}
}

length()
                       
It is used to find the string length.

Syntax: object.length()

charAt(): Returns the chat at the specified index of the string.

Syntax: charAt(index);

indexOf(): Returns the index of the first occurrence of the specified character or -1 if the character not found.

Syntax:           indexOf(char);
indexOf(char,fromposition);

lastIndexOf:   Returns the index of the last occurrence of the specified character.

Syntax:          
lastIndexOf(char, fromposition);
lastIndexOf(char);
lastIndexOf(String);
lastIndexOf(string,fromposition);

subString:      To print the string from specified position to specified characters

Syntax:-     subString(begin Index, end index);
 
replace: To replace the old character with new char.

Syntax :          replace(old character, new character)

startsWith:     Returns true if the character sequence represented by the argument is a prefix of the character sequence represented by the string.

Syntax:-          startsWith(String prefix);
endsWith(string);

toLowerCase:                        To convert the string into lower case

syntax:-           object.toLowerCase()

toUpperCase:                        To convert the string into uppercase

Syntax:                       object.toUpperCase()

trim:                removes white spaces from both ends.

Syntax:           object.trim()

equals:            it returns true if both the strings are equal.

Syntax:                1.object.equals(string)
2.object.equalsIgnoreCase(string)

comparateTo:                        To know whether two string are identical for sorting applications you need to know which is <(or)=(or)>

Syntax            :           object.compareTo(“string”);

getChars         : it is used to get the characters from the string and stores in to an array.

Syntax:-          object.getchars(sourcestart,sourceend,chararray,targetstart)

contact:           we can concatenate the two strings.
Syntax:           object.contact(string)

toString:         It is used to convert the other data types to string data type.

Syntax            :           String obj=object.toString();

class Sample
{
public static void main(String args[])
{
String s="VISION";
System.out.println("Length: "+s.length());
System.out.println("Char AT: "+s.charAt(3));
System.out.println("INdex Of: "+s.indexOf(3));
System.out.println("Welcome To"+s.lastIndexOf("To"));
System.out.println("Sub string: "+s.substring(2,3));
System.out.println("Replace: "+s.replace('s','k'));
System.out.println("Starts With: "+s.startsWith("Vis"));
System.out.println("Ends With: "+s.endsWith("on"));
System.out.println("Tolowercase: "+s.toLowerCase());
System.out.println("Touppercase: "+s.toUpperCase());
System.out.println("Trim: "+s.trim());
System.out.println("Equals: "+s.equals("vision"));
System.out.println("Equalsignorecase: "+s.equalsIgnoreCase("vision”));
System.out.println("Compare: "+s.compareTo("vision"));
char c[]=new char[10];
String s1="welcome to vision";
s1.getChars(3,5,c,0);
System.out.println(s);
s1.concat(s);
System.out.println(s1);
}
}

String Buffers

capacity():      It will display the total allocated capacity of the string buffer.

Syntax:           StringBuffer object.capacity();

ensureCapacity:        It is used to preallocate room for a certain no.of characters after string buffer has been constructed.

Syntax:           object.ensureCapacity(capacity)

setLength( ):   it is used to set the length of the buffer.

Syntax:           object.setLength(n)

charAt():        it is used to get the char at the specified location
Syntax:           object.charAt(n)

setCharAt( ):  it is used to set the character at specified location.       

Syntax:           object.setCharAt(n,char)

append( ):       The append( )method concatenates the string representation of any other type of data to end of the invoking string buffer object.
Syntax:           object.append(string)
object.append(int num)
object.append(object)
insert( ):          it is used to insert one string into another.
Syntax:           1.object.insert(int num,string)
2.object.insert(int num,char)
3.object.insert(int num,object)

reverse( ):       It is used to reverse the string.
Syntax:           object.reverse( )

delete( ):          to remove  characters from the specified location.
Syntax:           object.delete(start,end)

deleteCharAt( ):        to delete a character at specified location.
Syntax:           object.deleteCharAt(n)

class Sample
{
public static void main(String args[])
{
StringBuffer s=new StringBuffer("vision");
System.out.println("Length: "+s.length());
System.out.println("Capacity: "+s.capacity());
s.ensureCapacity(10);
s.setLength(5);
System.out.println("length: "+s);
s.setCharAt(3,'i');
System.out.println("Set char at: "+s);
s.append("hello").append(20).append("vision");
System.out.println("Append: "+s);
s.insert(3,"Insert");
System.out.println("Insert: "+s);
s.insert(4,"k");
System.out.println("insert: "+s);
s.reverse();
System.out.println("reverse: "+s);
s.delete(5,5);
System.out.println("Delete: "+s);
s.deleteCharAt(3);
System.out.println("delete char at: "+s);
}
}

For
More Explanation
&
Online Classes

Contact Us:
+919885348743