String Class

As in most other languages, in java also it is specified by enclosing a sequence of characters between a pair of double quotes,Strings, which are widely used in Java programming, are a sequence of characters. In the Java programming language, strings are objects.

The Java platform provides the String class to create and manipulate strings.

Declaring Strings:
The most direct way to create a string is to write:

String name = "Your Name";

Example 

class StringTest {

    public static void main(String[] args) {
        String name = "Your Name";
        String twoLine = " Line One \n Line Two";
        String quotes = "\"This is in quotes \" ";
        System.out.println(name);
        System.out.println(twoLine);
        System.out.println(quotes);
    }
}

Output :
anup
 Line One 
 Line Two
"This is in quotes " 


Whenever it encounters a string literal in your code, the compiler creates a String object with its value in this case, "Your Name'.


As with any other object, you can create String objects by using the new keyword and a constructor. The String class has eleven constructors that allow you to provide the initial value of the string using different sources, such as an array of characters.

public class CharArray{

   public static void main(String args[]){
      char[] charArray = { 'h', 'e', 'l', 'l', 'o', '.'};
      String helloString = new String(charArray);
      System.out.println( helloString );
   }
}

Output
hello.

class StringTest {

    public static void main(String[] args) {
        String v1="45";
        String v2="46";
        System.out.println(v1+v2);
    }
}

Output 
4546

String Class Methods

	Methods with Description
1	char - charAt(int index) Returns the character at the specified index.
2	int - compareTo(Object o) Compares this String to another Object.
3	int - compareTo(String anotherString) Compares two strings lexicographically.
4	int - compareToIgnoreCase(String str) Compares two strings lexicographically, ignoring case differences.
5	String - concat(String str) Concatenates the specified string to the end of this string.
6	boolean - contentEquals(StringBuffer sb) Returns true if and only if this String represents the same sequence of characters as the specified StringBuffer.
7	static - String copyValueOf(char[] data) Returns a String that represents the character sequence in the array specified.
8	static - String copyValueOf(char[] data, int offset, int count) Returns a String that represents the character sequence in the array specified.
9	boolean - endsWith(String suffix) Tests if this string ends with the specified suffix.
10	boolean - equals(Object anObject) Compares this string to the specified object.
11	boolean - equalsIgnoreCase(String anotherString) Compares this String to another String, ignoring case considerations.
12	byte - getBytes() Encodes this String into a sequence of bytes using the platform's default charset, storing the result into a new byte array.
13	byte[]- getBytes(String charsetName Encodes this String into a sequence of bytes using the named charset, storing the result into a new byte array.
14	void - getChars(int srcBegin, int srcEnd, char[] dst, int dstBegin) Copies characters from this string into the destination character array.
15	int - hashCode() Returns a hash code for this string.
16	int - indexOf(int ch) Returns the index within this string of the first occurrence of the specified character.
17	int - indexOf(int ch, int fromIndex) Returns the index within this string of the first occurrence of the specified character, starting the search at the specified index.
18	int - indexOf(String str) Returns the index within this string of the first occurrence of the specified substring.
19	int - indexOf(String str, int fromIndex Returns the index within this string of the first occurrence of the specified substring, starting at the specified index.
20	String - intern() Returns a canonical representation for the string object.
21	int - lastIndexOf(int ch) Returns the index within this string of the last occurrence of the specified character.
22	int - lastIndexOf(int ch, int fromIndex) Returns the index within this string of the last occurrence of the specified character, searching backward starting at the specified index.
23	int - lastIndexOf(String str) Returns the index within this string of the rightmost occurrence of the specified substring.
24	int - lastIndexOf(String str, int fromIndex) Returns the index within this string of the last occurrence of the specified substring, searching backward starting at the specified index.
25	int - length() Returns the length of this string.
26	boolean - matches(String regex) Tells whether or not this string matches the given regular expression.
27	boolean - regionMatches(boolean ignoreCase, int toffset, String other, int ooffset, int len) Tests if two string regions are equal.
28	boolean - regionMatches(int toffset, String other, int ooffset, int len) Tests if two string regions are equal.
29	String - replace(char oldChar, char newChar) Returns a new string resulting from replacing all occurrences of oldChar in this string with newChar.
30	String - replaceAll(String regex, String replacement Replaces each substring of this string that matches the given regular expression with the given replacement.
31	String - replaceFirst(String regex, String replacement) Replaces the first substring of this string that matches the given regular expression with the given replacement.
32	String[] - split(String regex) Splits this string around matches of the given regular expression.
33	String[] - split(String regex, int limit) Splits this string around matches of the given regular expression.
34	boolean - startsWith(String prefix) Tests if this string starts with the specified prefix.
35	boolean - startsWith(String prefix, int toffset) Tests if this string starts with the specified prefix beginning a specified index.
36	CharSequence - subSequence(int beginIndex, int endIndex) Returns a new character sequence that is a subsequence of this sequence.
37	String - substring(int beginIndex) Returns a new string that is a substring of this string.
38	String - substring(int beginIndex, int endIndex) Returns a new string that is a substring of this string.
39	char[] - toCharArray() Converts this string to a new character array.
40	String - toLowerCase() Converts all of the characters in this String to lower case using the rules of the default locale.
41	String - toLowerCase(Locale locale) Converts all of the characters in this String to lower case using the rules of the given Locale.
42	String - toString() This object (which is already a string!) is itself returned.
43	String - toUpperCase() Converts all of the characters in this String to upper case using the rules of the default locale.
44	String - toUpperCase(Locale locale) Converts all of the characters in this String to upper case using the rules of the given Locale.
45	String - trim() Returns a copy of the string, with leading and trailing whitespace omitted.
46	static - String valueOf(primitive data type x) Returns the string representation of the passed data type argument.